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Taking Power Skiving to New Levels

The enormous productivity and quality benefits of the Gleason Power Skiving process are now available for a wide range of applications. Whether you're producing small or large, internal or external cylindrical gears, soft cutting or fine-finish machining - there's a 'total' solution to fit your needs. This includes machines for small, medium and large workpieces, automation, tooling, cutter pre-setting, as well as simulation and technology software. Article Courtesy of Gleason Corporation
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1 Deburring & Finishing Gears with Power Brushes (March/April 1989)

Why Brushes? In this age of hi-tech, robots, automatic machines, machining cells, etc., is there a niche somewhere for power brushes? Let me answer by asking another question. What tool does the gear manufacturer have in his arsenal that allows him to deburr green gears, hardened gears, hobbed gears, ground gears and shaved gears? What tool allows him to deburr powder metal gears - green and sintered - brass gears, bronze gears, stainless gears made of exotic materials such as inconel, waspaloy, or hastaloy, and fiber and plastic gears? How about spur gears, helical gears, sprockets, both internal and external splines, clutch teeth and pump gears?

2 How to Design and Install Bevel Gears for Optimum Performance - Lessons Learned (June/July 2013)

Bevel gears must be assembled in a specific way to ensure smooth running and optimum load distribution between gears. While it is certainly true that the "setting" or "laying out" of a pair of bevel gears is more complicated than laying out a pair of spur gears, it is also true that following the correct procedure can make the task much easier. You cannot install bevel gears in the same manner as spur and helical gears and expect them to behave and perform as well; to optimize the performance of any two bevel gears, the gears must be positioned together so that they run smoothly without binding and/or excessive backlash.

3 Net-Shape Forged Gears - The State of the Art (January/February 2002)

Traditionally, high-quality gears are cut to shape from forged blanks. Great accuracy can be obtained through shaving and grinding of tooth forms, enhancing the power capacity, life and quietness of geared power transmissions. In the 1950s, a process was developed for forging gears with teeth that requires little or no metal to be removed to achieve final geometry. The initial process development was undertaken in Germany for the manufacture of bevel gears for automobile differentials and was stimulated by the lack of available gear cutting equipment at that time. Later attention has turned to the forging of spur and helical gears, which are more difficult to form due to the radial disposition of their teeth compared with bevel gears. The main driver of these developments, in common with most component manufacturing, is cost. Forming gears rather than cutting them results in increased yield from raw material and also can increase productivity. Forging gears is therefore of greater advantage for large batch quantities, such as required by the automotive industry.

4 Surface Fatigue Life on CBN and Vitreous Ground Carburized and Hardened AISA 9310 Spur Gears (January/February 1990)

Spur gear surface endurance tests were conducted to investigate CBN ground AISI 9310 spur gears for use in aircraft applications, to determine their endurance characteristics and to compare the results with the endurance of standard vitreous ground AISI 9310 spur gears. Tests were conducted with VIM-VAR AISI 9210 carburized and hardened gears that were finish ground with either CBN or vitreous grinding methods. Test conditions were an inlet oil temperature of 320 K (116 degree F), an outlet oil temperature of 350 K (170 degree F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. The CBN ground gears exhibited a surface fatigue life that was slightly better than the vitreous ground gears. The subsurface residual stress of the CBN ground gears was approximately the same as that for the standard vitreous ground gears for the CBN grinding method used.

5 Comparative Load Capacity Evaluation of CBN-Finished Gears (May/June 1990)

Cubic boron nitride (CBN) finishing of carburized gearing has been shown to have certain economic and geometric advantages and, as a result, it has been applied to a wide variety of precision gears in many different applications. In critical applications such as aerospace drive systems, however, any new process must be carefully evaluated before it is used in a production application. Because of the advantages associated with this process, a test program was instituted to evaluate the load capacity of aerospace-quality gears finished by the CBN process as compared to geometrically identical gears finished by conventional grinding processes. This article presents a brief description of the CBN process, its advantages in an aerospace application, and the results of an extensive test program conducted by Boeing Helicopters (BH) aimed at an evaluation of the effects of this process on the scoring, surface durability, and bending fatigue properties of spur gears. In addition, the results of an x-ray diffraction study to determine the surface and subsurface residual stress distributions of both shot-peened and nonshot-peened CBN-ground gears as compared to similar conventionally ground gears are also presented.

6 Generation of Helical Gears with New Surface Topology by Application of CNC Machines (January/February 1994)

Analysis of helical involute gears by tooth contact analysis shows that such gears are very sensitive to angular misalignment leading to edge contact and the potential for high vibration. A new topology of tooth surfaces of helical gears that enables a favorable bearing contact and a reduced level of vibration is described. Methods for grinding helical gears with the new topology are proposed. A TCA program simulating the meshing and contact of helical gears with the new topology has been developed. Numerical examples that illustrate the proposed ideas are discussed.

7 Hypoid Gears: Tribology Aspects in Angular Transmission Systems, Part VII (June/July 2011)

Hypoid gears are the paragon of gearing. To establish line contact between the pitches in hypoid gears, the kinematically correct pitch surfaces have to be determined based on the axoids. In cylindrical and bevel gears, the axoids are identical to the pitch surfaces and their diameter or cone angle can be calculated simply by using the knowledge about number of teeth and module or ratio and shaft angle. In hypoid gears, a rather complex approach is required to find the location of the teeth—even before any information about flank form can be considered. This article is part seven of an eight-part series on the tribology aspects of angular gear drives.

8 Performance Analysis of Hypoid Gears by Tooth Flank Form Measurement (July/August 2002)

The traditional way of controlling the quality of hypoid gears' tooth flank form is to check the tooth flank contact patterns. But it is not easy to exactly judge the tooth flank form quality by the contact pattern. In recent years, it has become possible to accurately measure the tooth flank form of hypoid gears by the point-to-point measuring method and the scanning measuring method. But the uses of measured data of the tooth flank form for hypoid gears have not yet been well developed in comparison with cylindrical involute gears. In this paper, the tooth flank form measurement of generated face-milled gears, face-hobbed gears and formulate/generated gears are reported. The authors discuss the advantages and disadvantages of scanning and point-to-point measuring of 3-D tooth flank forms of hypoid gears and introduce some examples of uses of measured data for high-quality production and performance prediction.

9 Repair of High-Value, High-Demand Spiral Bevel Gears by Superfinishing (October 2012)

Following is a report on the R&D findings regarding remediation of high-value, high-demand spiral bevel gears for the UH–60 helicopter tail rotor drivetrain. As spiral bevel gears for the UH–60 helicopter are in generally High-Demand due to the needs of new aircraft production and the overhaul and repair of aircraft returning from service, acquisition of new spiral bevel gears in support of R&D activities is very challenging. To compensate, an assessment was done of a then-emerging superfinishing method—i.e., the micromachining process (MPP)—as a potential repair technique for spiral bevel gears, as well as a way to enhance their performance and durability. The results are described in this paper.

10 Super-Reduction Hypoid Gears (August 2011)

Super-reduction hypoid gears (SRH) are bevel worm gears with certain differences regarding hypoid gears. If two axes are positioned in space and the task is to transmit motion and torque between them using some kind of gears with a ratio above 5 and even higher than 50, the following cases are commonly known. Tribology Aspects in Angular Transmission Systems, Part VIII.

11 Comparison of Surface Durability & Dynamic Performance of Powder Metal & Steel Gears (September/October 1995)

Surface-hardened, sintered powder metal gears are increasingly used in power transmissions to reduce the cost of gear production. One important problem is how to design with surface durability, given the porous nature of sintered gears. Many articles have been written about mechanical characteristics, such as tensile and bending strength, of sintered materials, and it is well-known that the pores existing on and below their surfaces affect their characteristics (Refs. 1-3). Power transmission gears are frequently employed under conditions of high speed and high load, and tooth surfaces are in contact with each other under a sliding-rolling contact condition. Therefore it is necessary to consider not only their mechanical, but also their tribological characteristics when designing sintered gears for surface durability.

12 Computer-Aided Design of the Stress Analysis of an Internal Spur Gear (May/June 1988)

Although there is plenty of information and data on the determination of geometry factors and bending strength of external gear teeth, the computation methods regarding internal gear design are less accessible. most of today's designs adopt the formulas for external gears and incorporate some kind of correction factors for internal gears. However, this design method is only an approximation because of the differences between internal gears and external gears. Indeed, the tooth shape of internal gears is different from that of external gears. One has a concave curve, while the other has a convex curve.

13 Development of Usable Bevel Gearset with Length and Profile Crowning (November/December 2015)

In the previous sections, the development of conjugate bevel gearsets via hand calculations was demonstrated. The goal of this exercise was to encourage the reader to gain a basic understanding of the theory of bevel gears. This knowledge will help gear engineers to better judge bevel gear design and their manufacturing methods. In order to make the basis of this learning experience even more realistic, this chapter will convert a conjugate bevel gearset into a gearset that is suitable in a real-world application. Length and profile crowning will be applied to the conjugate flank surfaces. Just as in the previous chapter, all computations are demonstrated as manual hand calculations. This also shows that bevel gear theory is not as complicated as commonly assumed.

14 Transmission Errors and Bearing Contact of Spur, Helical, and Spiral Bevel Gears (July/August 1990)

An investigation of transmission errors and bearing contact of spur, helical, and spiral bevel gears was performed. Modified tooth surfaces for these gears have been proposed in order to absorb linear transmission errors caused by gear misalignment and to localize the bearing contact. Numerical examples for spur, helical, and spiral bevel gears are presented to illustrate the behavior of the modified gear surfaces with respect to misalignment and errors of assembly. The numerical results indicate that the modified surfaces will perform with a low level of transmission error in non-ideal operating environments.

15 Minimization of In-Process Corrosion of Aerospace Gears (July/August 2002)

Carbon steels have primarily been used to manufacture aerospace gears due to the steels' mechanical characteristics. An alloyed low carbon steel is easily case-hardened to obtain a hard wear surface while maintaining the ductile core characteristics. The microstructure achieved will accept the heavy loading, shocks, and elevated temperatures that gears typically experience in applications. The carbon steel machinability allows for general machining practices to be employed when producing aerospace gears versus the more advanced metal removal processes required by stainless and nickel-based alloys.

16 Direct Gear Design for Spur and Helical Involute Gears (September/October 2002)

Modern gear design is generally based on standard tools. This makes gear design quite simple (almost like selecting fasteners), economical, and available for everyone, reducing tooling expenses and inventory. At the same time, it is well known that universal standard tools provide gears with less than optimum performance and - in some cases - do not allow for finding acceptable gear solutions. Application specifies, including low noise and vibration, high density of power transmission (lighter weight, smaller size) and others, require gears with nonstandard parameters. That's why, for example, aviation gear transmissions use tool profiles with custom proportions, such as pressure angle, addendum, and whole depth. The following considerations make application of nonstandard gears suitable and cost-efficient:

17 Face Gears: An Interesting Alternative for Special Applications - Calculation, Production and Use (September/October 2001)

Crown gearings are not a new type of gear system. On the contrary, they have been in use since very early times for various tasks. Their earliest form is that of the driving sprocket, found in ancient Roman watermills or Dutch windmills. The first principles of gear geometry and simple methods of production (shaper cutting) were developed in the 1940s. In the 1950s, however, crown gears' importance declined. Their tasks were, for example, taken over by bevel gears, which were easier to manufacture and could transmit greater power. Current subject literature accordingly contains very little information on crown gears, directed mainly to pointing out their limitations (Ref. 1).

18 Generating Precision Spur Gears By Wire EDM (May/June 1996)

Over the past decade, the wire electrical discharge machine (EDM) has become an increasingly important tool for machining non-standard shapes. It has even been used to cut gears and gear cavities for plastic molds. While generally accepted as a quick and versatile method for cutting spur gears, the EDM gear has lacked the precision of a mechanically machined or ground gear. We suspected that many of the errors associated with these gears were caused by inexact setup procedures, poor tool path control and improper cutting parameters. We decided to test the potential for the wire EDM to make the most accurate gear possible.

19 Helical Gears With Circular Arc Teeth: Simulation of Conditions of Meshing and Bearing Contact (July/August 1987)

Circular arc helical gears have been proposed by Wildhaber and Novikov (Wildhaber-Novikov gears). These types of gears became very popular in the sixties, and many authors in Russia, Germany, Japan and the People's Republic of China made valuable contributions to this area. The history of their researches can be the subject of a special investigation, and the authors understand that their references cover only a very small part of the bibliography on this topic.

20 Long-Life, Low-cost, Near-Net-Shape forged Gears (May/June 1995)

Near-net gear forging today is producing longer life gears at significantly lower costs than traditional manufacturing techniques. Advances in forging equipment, controls and die-making capability have been combined to produce commercially viable near-net-shape gears in diameters up to 17" with minimum stock allowances. These forged gears require only minimal finishing to meet part tolerance specifications.

21 Practical Analysis of Highly-Loaded Gears by Using the Modified-Scoring Index Calculation Method (September/October 1986)

The power of high speed gears for use in the petrochemical industry and power stations is always increasing. Today gears with ratings of up to 70,000kW are already in service. For such gears, the failure mode of scoring can become the limiting constraint. The validity of an analytical method to predict scoring resistance is, therefore, becoming increasingly important.

22 Non-Standard Cylindrical Gears (November/December 2004)

Curved face width (CFW) spur gears are not popular in the gear industry. But these non-metallic gears have advantages over standard spur gears: higher contact ratio, higher tooth stiffness, and lower contact and bending stresses.

23 Precision Forged Spiral Bevel Gears (August/September 1984)

A recent U.S. Army Tank-Automotive Command project, conducted by Battelle's Columbus Laboratories. successfully developed the methodology of CAD/CAM procedures for manufacturing dies (via EDM) for forging spiral bevel gears. Further, it demonstrated that precision forging of spiral bevel gears is a practical production technique. Although no detailed economic evaluation was made in this study, it is expected that precision forging offers an attractive alternative to the costly gear cutting operations for producing spiral bevel gears.

24 Gear Tooth Surface Roughness of Helical Gears Manufactured by a Form Milling Cutter (September/October 2015)

Manufacturing involute gears using form grinding or form milling wheels are beneficial to hobs in some special cases, such as small scale production and, the obvious, manufacture of internal gears. To manufacture involute gears correctly the form wheel must be purpose-designed, and in this paper the geometry of the form wheel is determined through inverse calculation. A mathematical model is presented where it is possible to determine the machined gear tooth surface in three dimensions, manufactured by this tool, taking the finite number of cutting edges into account. The model is validated by comparing calculated results with the observed results of a gear manufactured by an indexable insert milling cutter.

25 Manufacturing Method of Large-Sized Spiral Bevel Gears in Cyclo-Palloid System Using Multi-Axis Control and Multi-Tasking Machine Tool (August 2011)

In this article, the authors calculated the numerical coordinates on the tooth surfaces of spiral bevel gears and then modeled the tooth profiles using a 3-D CAD system. They then manufactured the large-sized spiral bevel gears based on a CAM process using multi-axis control and multi-tasking machine tooling. The real tooth surfaces were measured using a coordinate measuring machine and the tooth flank form errors were detected using the measured coordinates. Moreover, the gears were meshed with each other and the tooth contact patterns were investigated. As a result, the validity of this manufacturing method was confirmed.

26 Controlling Tooth Loads In Helical Gears (March/April 1986)

Helical gears can drive either nonparallel or parallel shafts. When these gears are used with nonparallel shafts, the contact is a point, and the design and manufacturing requirements are less critical than for gears driving parallel shafts.

27 Calculation of Tooth Root Load Carrying Capacity of Beveloid Gears (June 2014)

In this paper, two developed methods of tooth root load carrying capacity calculations for beveloid gears with parallel axes are presented, in part utilizing WZL software GearGenerator and ZaKo3D. One method calculates the tooth root load-carrying capacity in an FE-based approach. For the other, analytic formulas are employed to calculate the tooth root load-carrying capacity of beveloid gears. To conclude, both methods are applied to a test gear. The methods are compared both to each other and to other tests on beveloid gears with parallel axes in test bench trials.

28 FZG Rig-Based Testing of Flank Load-Carrying Capacity Internal Gears (June/July 2012)

Micropitting, pitting and wear are typical gear failure modes that can occur on the flanks of slowly operated and highly stressed internal gears. However, the calculation methods for the flank load-carrying capacity have mainly been established on the basis of experimental investigations of external gears. This paper describes the design and functionality of the newly developed test rigs for internal gears and shows basic results of the theoretical studies. It furthermore presents basic examples of experimental test results.

29 Zerol Bevel Gears: Tribology Aspects in Angular Transmission Systems, Part III (November/December 2010)

Zerol bevel gears are the special case of spiral bevel gears with a spiral angle of 0°. They are manufactured in a single-indexing face milling process with large cutter diameters, an extra deep tooth profile and tapered tooth depth.

30 Load-Sharing Model for Polymer Cylindrical Gears (November/December 2011)

This paper presents an original method to compute the loaded mechanical behavior of polymer gears. Polymer gears can be used without lubricant, have quieter mesh, are more resistant to corrosion, and are lighter in weight. Therefore their application fields are continually increasing. Nevertheless, the mechanical behavior of polymer materials is very complex because it depends on time, history of displacement and temperature. In addition, for several polymers, humidity is another factor to be taken into account. The particular case of polyamide 6.6 is studied in this paper.

31 Big Gears Better and Faster (January/February 2011)

Indexable carbide insert cutting tools for gears are nothing new. But big gears have recently become a very big business. The result is that there's been a renewed interest in carbide insert cutting tools.

32 Crowned Spur Gears: Optimal Geometry and Generation (September/October 1988)

Involute spur gears are very sensitive to gear misalignment. Misalignment will cause the shift of the bearing contact toward the edge of the gear tooth surfaces and transmission errors that increase gear noise. Many efforts have been made to improve the bearing contact of misaligned spur gears by crowning the pinion tooth surface. Wildhaber(1) had proposed various methods of crowning that can be achieved in the process of gear generation. Maag engineers have used crowning for making longitudinal corrections (Fig. 1a); modifying involute tooth profile uniformly across the face width (Fig. 1b); combining these two functions in Fig. 1c and performing topological modification (Fig. 1d) that can provide any deviation of the crowned tooth surface from a regular involute surface. (2)

33 Manufacturers Guide to Heat Treating Large Gears (March/April 2012)

The large gears found in mining, steel, construction, off-road, marine and energy applications—massive and robust in nature—need to tackle the greatest production demands. This, in turn, means that a special emphasis must be put on the heat treating methods used to increase the wear resistance and strength properties of gears this size.

34 Longitudinal Load Distribution Factor for Straddle- and Overhang-Mounted Spur Gears (July/August 1987)

A pair of spur gears generally has an effective lead error which is caused, not only by manufacturing and assembling errors, but also by the deformations of shafts, bearings and housings due to the transmitted load. The longitudinal load distribution on a contact line of the teeth of the gears is not uniform because of the effective lead error.

35 Pressure Angle Changes in the Transverse Plane for Circular Cut Spiral Bevel Gears (September/October 1986)

Recently it has been suggested that the transverse plane may be very useful in studying the kinematics and dynamics of spiral bevel gears. The transverse plane is perpendicular to the pitch and axial planes as shown in Fig. 1. Buckingham has suggested that a spiral bevel gear may be viewed as a limited form of a "stepped" straight-tooth gear as in Fig. 2. The transverse plane is customarily used in the study of straight toothed bevel gears.

36 Improvement in Load Capacity of Crossed Helical Gears (January/February 1987)

Crossed helical gear sets are used to transmit power and motion between non-intersecting and non-parallel axes. Both of the gears that mesh with each other are involute helical gears, and a point contact is made between them. They can stand a small change in the center distance and the shaft angle without any impairment in the accuracy of transmitting motion.

37 Checking Large Gears (March/April 1987)

Gear manufacturing schedules that provide both quality and economy are dependent on efficient quality control techniques with reliable measuring equipment. Given the multitude of possible gear deviations, which can be found only by systematic and detailed measuring of the gear teeth, adequate quality control systems are needed. This is especially true for large gears, on which remachining or rejected workpieces create very high costs. First, observation of the gears allows adjustment of the settings on the equipment right at the beginning of the process and helps to avoid unproductive working cycles. Second, the knowledge of deviations produced on the workpiece helps disclose chance inadequacies on the production side: e.g., faults in the machines and tools used, and provides an opportunity to remedy them.

38 Effect of Shot Peening on Surface Fatigue Life of Carburized and Hardened AISI 1910 Spur Gears (January/February 1986)

Gear surface fatigue endurance tests were conducted on two groups of 10 gears each of carburized and hardened AlSI 9310 spur gears manufactured from the same heat of material

39 Lubricant Jet Flow Phenomena in Spur and Helical Gears (January/February 1987)

In the gearing industry, gears are lubricated and cooled by various methods. At low to moderate speeds and loads, gears may be partly submerged in the lubricant which provides lubrication and cooling by splash lubrication. With splash lubrication, power loss increases considerably with speed. This is partially because of churning losses. It is shown that gear scoring and surface pitting can occur when the gear teeth are not adequately lubricated and cooled.

40 Worm Gear Measurement (September/October 1997)

Several articles have appeared in this publication in recent years dealing with the principles and ways in which the inspection of gears can be carried out, but these have dealt chiefly with spur, helical and bevel gearing, whereas worm gearing, while sharing certain common features, also requires an emphasis in certain areas that cause it to stand apart. For example, while worm gears transmit motion between nonparallel shafts, as do bevel and hypoid gears, they usually incorporate much higher ratios and are used in applications for which bevel would not be considered, including drives for rotary and indexing tables in machine tools, where close tolerance of positioning and backlash elimination are critical, and in situations where accuracy of pitch and profile are necessary for uniform transmission at speed, such as elevators, turbine governor drives and speed increasers, where worm gears can operate at up to 24,000 rpm.

41 Development of High-Hardness-Cast Gears for High-Power Mining Applications (January/February 2017)

Multiple possibilities are available to increase the transmissible power of girth gears. These solutions include: using a larger module, increasing of the gear diameter through the number of teeth, enlarging the face width, and increasing the hardness of the base material. The first three parameters are mostly limited by cutting machine capability. Module, outside diameter, and face width (for a cast gear) can theoretically be increased to infinity, but not the cutting machine dimensions. There are also practical limits with respect to the installation of very large diameter/large face width gears.

42 Optimal Flank Forms for Large Bevel Gears (November/December 2016)

At first sight the appearance of 5-axis milling for bevel gears opens new possibilities in flank form design. Since in comparison to existing machining methods applying cutter heads no kinematic restrictions exist for 5-axis milling technology, any flank form can be machined. Nevertheless the basic requirements for bevel gears did not change. Specifications and functional requirements like load carrying capacity and running behavior are still increasing demands for design and manufacturing. This paper describes the demands for gear design and gives an overview about different design principles in the context of the surrounding periphery of the gear set.

43 Development of a Face Hobbed Spiral Bevel Gearset (September/October 2015)

This article is the fourth installment in Gear Technology's series of excerpts from Dr. Hermann J. Stadtfeld's book, Gleason Bevel Gear Technology. The first three excerpts can be found in our June, July and August 2015 issues. In the previous chapter, we demonstrated the development of a face-milled spiral bevel gearset. In this section, an analogue face-hobbed bevel gearset is derived.

44 Importance of Contact Pattern in Assembly of Bevel vs Cylindrical Gears (August 2014)

Why is there so much emphasis on the tooth contact pattern for bevel gears in the assembled condition and not so for cylindrical gears, etc?

45 Girth Gears - More than Just Metal and Teeth (May 2017)

Large, multi-segmented girth gears do not behave like the relatively compact, rigid, monolithic structures we typically envision when discussing gear manufacturing. Girth gears are very large, non-rigid structures that require special care during the machining of individual mating segments as well as the assembled gear blank itself.

46 Design of Internal Helical Gears (March/April 1989)

In principal, the design of internal helical gear teeth is the same as that for external helical gears. Any of the basic rack forms used for external helical gears may be applied to internal helical gears. The internal gear drive, however, has several limitations; not only all those which apply to external gears, but also several others which are peculiar to internal gears. As with external gears, in order to secure effective tooth action, interferences must be avoided. The possible interferences on an internal gear drive are as follows: 1. Involute interference. To avoid this, all of the working profile of the internal tooth must be of involute form.

47 Same Hob for Two Gears (September/October 2016)

I make all the double helical gears that go into a gearbox — four different gears in this unit. If the gear module for the bull gear and the intermediate gear are the same (these are the two individual gears that mate), and the gear module for the high-speed pinion and high-speed gears are the same (these are the other two individual gears that mate in the gear box as well), is it then possible to just use two hobs in this setup to make all four gears, since they mate together with each other? We are currently using a different gear hob for each gear.

48 Performance of Gears Manufactured by 5-Axis Milling (March/April 2017)

Free form milling of gears becomes more and more important as a flexible machining process for gears. Reasons for that are high degrees of freedom as the usage of universal tool geometry and machine tools is possible. This allows flexible machining of various gear types and sizes with one manufacturing system. This paper deals with manufacturing, quality and performance of gears made by free form milling. The focus is set on specific process properties of the parts. The potential of free form milling is investigated in cutting tests of a common standard gear. The component properties are analyzed and flank load-carrying capacity of the gears is derived by running trials on back-to-back test benches. Hereby the characteristics of gears made by free form milling and capability in comparison with conventionally manufactured gears will be shown.

49 Shaper Cutters-Design & Applications Part 1 (March/April 1990)

Gear shaping is one of the most popular production choices in gear manufacturing. While the gear shaping process is really the most versatile of all the gear manufacturing methods and can cut a wide variety of gears, certain types of gears can only be cut by this process. These are gears closely adjacent to shoulders; gears adjacent to other gears, such as on countershafts; internal gears, either open or blind ended; crown or face gears; herringbone gears of the solid configuration of with a small center groove; rack; parts with filled-in spaces or teeth, such as are used in some clutches.

50 Loaded Behavior of Gears Made of Fiber-Reinforced PA6 (July 2014)

This paper presents an original method for computing the loaded mechanical behavior of fiber reinforced polymer gears. Although thermoplastic gears are unsuitable for application transmitting high torque, adding fibers can significantly increase their performance. The particular case of polyamide 6 + 30% glass fibers is studied in this paper.

51 Center Distance Variations for Internal Gears (October 2012)

While external involute gears are very tolerant of center distance variations, what are the center distance constraints for internal gears?

52 High-Temperature Testing of Stanyl Plastic Gears: A Comparison with Tensile Fatigue Data (March/April 2010)

This paper shows an experimental study on the fatigue lifetime of high-heat polyamide (Stanyl) gears running in oil at 140°C. Based on previous works (Refs. 1–2), an analysis is made correcting for tooth bending and calculating actual root stresses. A comparison with tensile bar fatigue data for the same materials at 140°C shows that a good correlation exists between gear fatigue data and tensile bar fatigue data. This insight provides a solid basis for gear designers to design plastic gears using actual material data.

53 Grinding Bevel Gears on Cylindrical Gear Grinding Machines (January/February 1994)

Power train designs which employ gears with cone angles of approximately 2 degrees to 5 degrees have become quite common. It is difficult, if not impossible, to grind these gears on conventional bevel gear grinding machines. Cylindrical gear grinding machines are better suited for this task. This article will provide an overview of this option and briefly introduce four grinding variation possibilities.

54 Camshaft Gears (November/December 1992)

One of our readers in England has asked for our help in locating published technical data and information on the design, manufacture, and inspection of camshaft gears. Although millions of these gears have been made and are in constant use, we are not aware of any formal material having been published. We would be pleased to hear from anyone who had knowledge of such information.

55 A Modular Approach to Computing Spiral Bevel Gears and Curvic Couplings (May/June 2000)

In general, bevel gears and curvic couplings are completely different elements. Bevel gears rotate on nonintersecting axis with a ratio based on the number of teeth. Curvic couplings work like a clutch (Fig. 1).

56 The Math of Noncircular Gearing (July/August 2000)

Noncircular gearing is not new. There are well-documented articles covering standard and high order elliptical gears, sinusoidal gears, logarithmic spiral gears, and circular gears mounted eccentrically. What these designs have in common is a pitch curve defined by a mathematical function. This article will cover noncircular gearing with free-form pitch curves, which, of course, includes all the aforementioned functions. This article also goes into the generation of teeth on the pitch curve, which is not usually covered in the technical literature. Needless to say, all this is possible only with the help of a computer.

57 High-Performance Sintered-Steel Gears for Transmissions and Machinery: A Critical Review (August 2012)

Except for higher-end gear applications found in automotive and aerospace transmissions, for example, high-performance, sintered-steel gears match wrought-steel gears in strength and geometrical quality. The enhanced P/M performance is due largely to advances in powder metallurgy over last two decades, such as selective surface densification, new materials and lubricants for high density and warm-die pressing. This paper is a review of the results of a decade of research and development of high- performance, sintered-steel gear prototypes.

58 The Alignment of High Speed Gears (January/February 2003)

This paper reviews the necessity for detailed specification, design and manufacture to achieve required performance in service. The precise definition of duty rating and a thorough understanding of the environmental conditions, whether it is in a marine or industrial application, is required to predict reliable performance of a gearbox through its service life. A case study relating to complex marine gears and other general practice is presented to review the techniques used by Allen Gears to design and develop a gearbox that integrates with the requirements of the whole machinery installation. Allen Gears has considerable experience in the design of a variety of industrial and marine gears(Ref. 1,2).

59 Profile Shift in External Parallel Axis Cylindrical Involute Gears (November/December 2001)

Early in the practice of involute gearing, virtually all gears were made with the teeth in a standard relationship to the reference pitch circle. This has the advantages that any two gears of the same pitch, helix angle and pressure angle can operate together, and that geometry calculations are relatively simple. It was soon realized, though, that there are greater advantages to be gained by modifying the relationship of the teeth to the reference pitch circle. The modifications are called profile shift.

60 Manufacturing of Forged and Extruded Gears (July/August 1990)

Traditional methods of manufacturing precision gears usually employ either hobbing or shaper cutting. Both of these processes rely upon generating the conjugate tooth form by moving the work-piece in a precise relation to the tool. Recently, attention has been given to forming gear teeth in a single step. Advantages to such a process include reduced production time, material savings, and improved performance characteristics. Drawbacks include complicated tool designs, non-uniformity of gears produced throughout the life of the tooling, and lengthy development times.

61 Cutting Hardened Gears (November/December 2002)

The need for improved power transmissions that use gears and gearboxes with smaller overall dimensions and with lower noise generation has left manufacturing engineers searching for different methods of gear processing. This search has led to the requirement of hardened gears.

62 The Design and Manufacture of Machined Plastic Gears (May/June 1985)

The use of plastic gearing is increasing steadily in new products. This is due in part to the availability of recent design data. Fatigue stress of plastic gears as a function of diametral pitch, pressure angle, pitch line velocity, lubrication and life cycles are described based on test information. Design procedures for plastic gears are presented.

63 Load Carrying Capacity of Screw Helical Gears with Steel Pinions and Plastic Wheels (July/August 2004)

There is an increasing significance of screw helical and worm gears that combine use of steel and plastics. This is shown by diverse and continuously rising use in the automotive and household appliance industries. The increasing requirements for such gears can be explained by the advantageous qualities of such a material combination in comparison with that of the traditional steel/bronze pairing.

64 How Are You Dealing with the Bias Error in Your Helical Gears (May 2009)

This paper initially defines bias error—the “twisted tooth phenomenon.” Using illustrations, we explain that bias error is a by-product of applying conventional, radial crowning methods to produced crowned leads on helical gears. The methods considered are gears that are finished, shaped, shaved, form and generated ground. The paper explains why bias error occurs in these methods and offers techniques used to limit/eliminate bias error. Sometimes, there may be a possibility to apply two methods to eliminate bias error. In those cases, the pros/cons of these methods will be reviewed.

65 Repair via Isotropic Superfinishing of Aircraft Transmission Gears (May 2009)

The objective of this paper is to demonstrate that transmission gears of rotary-wing aircraft, which are typically scrapped due to minor foreign object damage (FOD) and grey staining, can be repaired and re-used with signifi cant cost avoidance. The isotropic superfinishing (ISF) process is used to repair the gear by removing surface damage. It has been demonstrated in this project that this surface damage can be removed while maintaining OEM specifications on gear size, geometry and metallurgy. Further, scrap CH-46 mix box spur pinions, repaired by the ISF process, were subjected to gear tooth strength and durability testing, and their performance compared with or exceeded that of new spur pinions procured from an approved Navy vendor. This clearly demonstrates the feasibility of the repair and re-use of precision transmission gears.

66 Longitudinal Load Distribution Factor of Helical Gears (July/August 1985)

The contact lines of a pair of helical gears move diagonally on the engaged tooth faces and their lengths consequently vary with the rotation of the gears.

67 A Further Study on High-Contact-Ratio Spur Gears in Mesh with Double-Scope Tooth Profile Modification (November/December 2008)

This paper will demonstrate that, unlike commonly used low-contact-ratio spur gears, high-contact-ratio spur gears can provide higher power-to-weight ratio, and can also achieve smoother running with lower transmission error (TE) variations.

68 Tooth Fillet Profile Optimization for Gears with Symmetric and Asymmetric Teeth (September/October 2009)

The gear tooth fillet is an area of maximum bending stress concentration. However, its profile is typically less specified in the gear drawing and hardly controlled during gear inspection in comparison with the gear tooth flanks. This paper presents a fillet profile optimization technique for gears with symmetric and asymmetric teeth based on FEA and a random search method. It allows achieving substantial bending stress reduction in comparison with traditionally designed gears. This bending stress reduction can be traded for higher load capacity, longer lifetime, lower noise and vibration and cost reduction.

69 Differential Gears (October 2012)

What are the manufacturing methods used to make bevel gears used in automotive differentials?

70 Big Gears - High Standards, High Profits (January/February 2009)

Natural resources—minerals, coal, oil, agricultural products, etc.—are the blessings that Mother Earth confers upon the nations of the world. But it takes unnaturally large gears to extract them.

71 Grinding Gears for Racing Transmissions (September/October 2009)

When you push 850 horsepower and 9,000 rpm through a racing transmission, you better hope it stands up. Transmission cases and gears strewn all over the racetrack do nothing to enhance your standing, nor that of your transmission supplier.

72 MicroPulse and MicroShift for Ground Bevel Gearsets (July 2017)

Grinding of bevel and hypoid gears creates on the surface a roughness structure with lines that are parallel to the root. Imperfections of those lines often repeat on preceding teeth, leading to a magnification of the amplitudes above the tooth mesh frequency and their higher harmonics. This phenomenon is known in grinding and has led in many cylindrical gear applications to an additional finishing operation (honing). Until now, in bevel and hypoid gear grinding, a short time lapping of pinion and gear after the grinding operation, is the only possibility to change the surface structure from the strongly root line oriented roughness lines to a diffuse structure.

73 Local 3-D Flank Form Optimizations for Bevel Gears (September/October 2003)

Optimizing the running behavior of bevel and hypoid gears means improving both noise behavior and load carrying capacity. Since load deflections change the relative position of pinion and ring gear, the position of the contact pattern will depend on the torque. Different contact positions require local 3-D flank form optimizations for improving a gear set.

74 True Bending Stress in Spur Gears (August 2007)

In this paper, an accurate FEM analysis has been done of the “true” stress at tooth root of spur gears in the function of the gear geometry. The obtained results confirm the importance of these differences.

75 Cylkro Gears: An Alternative in Mechanical Power Transmission (May/June 1996)

Bevel gears have been the standard for several decades in situations where power transmission has to occur between shafts mounted at a given angle. Now a new approach has been developed that challenges the bevel gear's de facto monopoly in such applications. The concept is based on the principle of the crown gear; i.e., a cylindrical pinion mates with a face gear. Crown Gear B.V. in Enschede, Holland, is the developer of these specialty gear teeth, which are marketed under the trade name Cylkro.

76 The Effect of Metallurgy on the Performance of Carburized Gears (March/April 1996)

Gears are designed to be manufactured, processed and used without failure throughout the design life of the gear. One of INFAC's objectives (*see p.24) is to help manufacture of gears to optimize performance and life. One way to achieve this is to identify failure mechanisms and then devise strategies to overcome them by modifying the manufacturing parameters.

77 Analysis and Testing of Gears with Asymmetric Involute Tooth Form and Optimized Fillet Form for Potential Application in Helicopter Main Drives (June/July 2011)

Gears with an asymmetric involute gear tooth form were analyzed to determine their bending and contact stresses relative to symmetric involute gear tooth designs, which are representative of helicopter main-drive gears.

78 Bevel Gears: Optimal High Speed Cutting (August 2007)

This article presents a summary of all factors that contribute to efficient and economical high-speed cutting of bevel and hypoid gears.

79 Drive Line Analysis for Tooth Contact Optimization of High-Power Spiral Bevel Gears (June/July 2011)

In the majority of spiral bevel gears, spherical crowning is used. The contact pattern is set to the center of the active tooth flank and the extent of the crowning is determined by experience. Feedback from service, as well as from full-torque bench tests of complete gear drives, has shown that this conventional design practice leads to loaded contact patterns, which are rarely optimal in location and extent. Oversized reliefs lead to small contact area, increased stresses and noise, whereas undersized reliefs result in an overly sensitive tooth contact.

80 Talking Truth to Power: Plastic Gears Taking Back Seat to No One (March/April 2013)

Automotive industry embraces proven yet evolving technology of plastic gears.

81 Gear Material Selection and Construction for Large Gears (January/February 2013)

A road map is presented listing critical considerations and optimal use of materials and methods in the construction of large gears.

82 The Relative Performance of Spur Gears Manufactured from Steel and PEEK (March/April 2012)

This paper seeks to compare the data generated from test rig shaft encoders and torque transducers when using steel-steel, steel-plastic and plastic-plastic gear combinations in order to understand the differences in performance of steel and plastic gears.

83 Determination and Optimization of the Contact Pattern of Worm Gears (March/April 2003)

The load capacity of worm gears is mainly influenced by the size and the position of the contact pattern.

84 Tooth Strength Study of Spur Planet Gears (September/October 1986)

In the design of any new gear drive, the performance of previous similar designs is very carefully considered. In the course of evaluating one such new design, the authors were faced with the task of comparing it with two similar existing systems, both of which were operating quite successfully. A problem arose, however, when it was realized that the bending stress levels of the two baselines differed substantially. In order to investigate these differences and realistically compare them to the proposed new design, a three-dimensional finite-element method (FEM) approach was applied to all three gears.

85 What "Ease-Off" shows about Bevel and Hypoid Gears (September/October 2001)

The configuration of flank corrections on bevel gears is subject to relatively narrow restrictions. As far as the gear set is concerned, the requirement is for the greatest possible contact zone to minimize flank compression. However, sufficient reserves in tooth depth and longitudinal direction for tooth contact displacement should be present. From the machine - and particularly from the tool - point of view, there are restrictions as to the type and magnitude of crowning that can be realized. Crowning is a circular correction. Different kinds of crowning are distinguished by their direction. Length crowning, for example, is a circular (or 2nd order) material removal, starting at a reference point and extending in tooth length or face width.

86 The Basics of Spiral Bevel Gears (January/February 2001)

This article also appears as Chapter 1 in the Gleason Corporation publication "Advanced Bevel Gear Technology." Gearing Principles in Cylindrical and Straight Bevel Gears The purpose of gears is to transmit motion and torque from one shaft to another. That transmission normally has to occur with a constant ratio, the lowest possible disturbances and the highest possible efficiency. Tooth profile, length and shape are derived from those requirements.

87 Basic Spur Gear Design (November/December 1988)

Primitive gears were known and used well over 2,000 years ago, and gears have taken their place as one of the basic machine mechanisms; yet, our knowledge and understanding of gearing principles is by no means complete. We see the development of faster and more reliable gear quality assessment and new, more productive manufacture of gears in higher materials hardness states. We have also seen improvement in gear applications and design, lubricants, coolants, finishes and noise and vibration control. All these advances push development in the direction of smaller, more compact applications, better material utilization and improved quietness, smoothness of operation and gear life. At the same time, we try to improve manufacturing cost-effectiveness, making use of highly repetitive and efficient gear manufacturing methods.

88 Calculation of Optimum Tooth Flank Corrections for Helical Gears (September/October 1988)

The load carrying behavior of gears is strongly influenced by local stress concentrations in the tooth root and by Hertzian pressure peaks in the tooth flanks produced by geometric deviations associated with manufacturing, assembly and deformation processes. The dynamic effects within the mesh are essentially determined by the engagement shock, the parametric excitation and also by the deviant tooth geometry.

89 Gears On Film (November/December 1996)

In our unceasing attempt to further educate our readers - and find new and creative ways to waste time at work - the Addendum staff has spent many long hours (and many dollars on popcorn) to bring you our latest research on gears in film.

90 Gears on the Firing Line (November/December 1998)

Air compressors are a good example of industrial machinery with components that rotate at very high speeds, up to 80,000 rpm. They are subject to very high rotational forces and often variable loads. Strong, high-precision gears for the power transmission trains that drive the impellers are critical components of machinery operating under such conditions.

91 A Computer Solution for the Dynamic Load, Lubricant Film Thickness, and Surface Temperatures in Spiral-Bevel Gears (March/April 1986)

Spiral-bevel gears, found in many machine tools, automobile rear-axle drives, and helicopter transmissions, are important elements for transmitting power.

92 Surface Structure Shift for Ground Bevel Gears (June 2017)

Ground bevel and hypoid gears have a designed motion error that defines parts of their NVH behavior. The surface structure is defined by the hard finishing process.

93 The Design and Manufacture of Plastic Gears Part II (July/August 1985)

Advancements in machining and assembly techniques of thermoplastic gearing along with new design data has lead to increased useage of polymeric materials. information on state of the art methods in fabrication of plastic gearing is presented and the importance of a proper backlash allowance at installation is discussed. Under controlled conditions, cast nylon gears show 8-14 dBA. lower noise level than three other gear materials tested.

94 The Music of the Gears (July/August 1998)

It should be obvious by now that gears are more than just mechanical components. We have brought you movies with gears and Shakespeare with gears, jewelry made out of gears and so on. Now we, the humble staff at Addendum, are proud to present gears in the world of music.

95 Transient EHL Analysis of Helical Gears (August 2016)

This paper addresses the lubrication of helical gears — especially those factors influencing lubricant film thickness and pressure. Contact between gear teeth is protected by the elastohydrodynamic lubrication (EHL) mechanism that occurs between nonconforming contact when pressure is high enough to cause large increases in lubricant viscosity due to the pressure-viscosity effect, and changes of component shape due to elastic deflection. Acting together, these effects lead to oil films that are stiff enough to separate the contacting surfaces and thus prevent significant metal-to-metal contact occurring in a well-designed gear pair.

96 Plastic Gear Design Basics (July/August 1996)

Plastic gears are serious alternatives to traditional metal gears in a wide variety of applications. The use of plastic gears has expanded from low-power, precision motion transmission into more demanding power transmission applications. As designers push the limits of acceptable plastic gear applications, more is learned about the behavior of plastics in gearing and how to take advantage of their unique characteristics.

97 Beveloid & Hypoloid Gears (May 2011)

Beveloids are helical gears with nonparallel shafts, with shaft angles generally between 5 degrees and 15 degrees. This is part VI in the Tribology Aspects in Angular Transmission Systems Series

98 Delivering Big Gears Fast (May 2013)

When a customer needed gears delivered in three weeks, here’s how Brevini Wind got it done.

99 Lapping and Superfinishing Effects on Surface Finish of Hypoid Gears and Transmission Errors (September/October 2008)

This presentation is an expansion of a previous study (Ref.1) by the authors on lapping effects on surface finish and transmission errors. It documents the effects of the superfinishing process on hypoid gears, surface finish and transmission errors.

100 Bending Fatigue Tests of Helicopter Case Carburized Gears: Influence on Material, Design and Manufacturing Parameters (November/December 2009)

A single tooth bending (STB) test procedure has been developed to optimally map gear design parameters. Also, a test program on case-carburized, aerospace standard gears has been conceived and performed in order to appreciate the influence of various technological parameters on fatigue resistance and to draw the curve shape up to the gigacycle region.

101 A Rational Procedure for Designing Minimum-Weight Gears (November/December 1991)

A simple, closed-form procedure is presented for designing minimum-weight spur and helical gearsets. The procedure includes methods for optimizing addendum modification for maximum pitting and wear resistance, bending strength, or scuffing resistance.

102 In-Situ Measurement of Stresses in Carburized Gears via Neutron Diffraction (May 2009)

This paper presents the results of research directed at measuring the total stress in a pair of statically loaded and carburized spur gears. Measurements were made to examine the change in total stress as a function of externally applied load and depth below the surface.

103 New Techniques for Aligning and Maintaining Large Ring Gears (September/October 1985)

This paper presents two new techniques for aligning and maintaining large ring gears. One technique uses lubricant temperature analysis, and the other uses stop action photography.

104 Mind-Boggling Gears (January/February 2016)

Square, rectangular, triangular, oval, even fishshaped — Clayton Boyer’s Weird Gears come in every shape except for circular, and they all work. If you’re interested in giving them a gander, check out Boyer’s Youtube video (just search “weird gears” and it’ll be right there at the top) to see them in motion

105 Setting Load Parameters for Viable Fatigue Testing of Gears in Powertrain Axles Part I: Single-Reduction Axles (August 2014)

This presentation introduces a new procedure that - derived from exact calculations - aids in determining the parameters of the validation testing of spiral bevel and hypoid gears in single-reduction axles.

106 Material Integrity in Molded Plastic Gears and its Dependence on Molding Practices (June 2008)

The quality of molded plastic gears is typically judged by dimensional feature measurements only. This practice overlooks potential deficiencies in the molding process.

107 Computer Aided Design (CAD) of Forging and Extrusion Dies for the Production of Gears by Forming (January/February 1985)

Material losses and long production times are two areas of conventional spur and helical gear manufacturing in which improvements can be made. Metalforming processes have been considered for manufacturing spur and helical gears, but these are costly due to the development times necessary for each new part design. Through a project funded by the U.S. Army Tank - Automotive Command, Battelle's Columbus Division has developed a technique for designing spur and helical gear forging and extrusion dies using computer aided techniques.

108 Grinding of Spur and Helical Gears (July/August 1992)

Grinding is a technique of finish-machining, utilizing an abrasive wheel. The rotating abrasive wheel, which id generally of special shape or form, when made to bear against a cylindrical shaped workpiece, under a set of specific geometrical relationships, will produce a precision spur or helical gear. In most instances the workpiece will already have gear teeth cut on it by a primary process, such as hobbing or shaping. There are essentially two techniques for grinding gears: form and generation. The basic principles of these techniques, with their advantages and disadvantages, are presented in this section.

109 Practical Optimization of Helical Gears Using Computer Software (May/June 1993)

The aim of this article is to show a practical procedure for designing optimum helical gears. The optimization procedure is adapted to technical limitations, and it is focused on real-world cases. To emphasize the applicability of the procedure presented here, the most common optimization techniques are described. Afterwards, a description of some of the functions to be optimized is given, limiting parameters and restrictions are defined, and, finally, a graphic method is described.

110 Little Gears, Big Picture (January/February 2015)

If there wasn’t such a thing as air (seriously, who even needs it?), gears might stand alone as the most ever-present entities on earth. They are literally everywhere you turn — a universal, inescapable part of the world we live in, sort of like Justin Bieber but with less hair gel and electronic synthesizers.

111 Lubricants and Lubrication of Plastic Gears (September/October 1993)

Surface measurement of any metal gear tooth contact surface will indicate some degree of peaks and valleys. When gears are placed in mesh, irregular contact surfaces are brought together in the typical combination of rolling and sliding motion. The surface peaks, or asperities, of one tooth randomly contact the asperities of the mating tooth. Under the right conditions, the asperities form momentary welds that are broken off as the gear tooth action continues. Increased friction and higher temperatures, plus wear debris introduced into the system are the result of this action.

112 Coarse Pitch Gears (May/June 1993)

This article discusses briefly some common manufacturing problems relating to coarse pitch gears and their suggested solutions. Most of the discussion will be limited to a low-quality production environment using universal machine tools.

113 The XL Gears Project (January/February 2014)

Much of the existing guidelines for making large, high-performance gears for wind turbine gearboxes exhibit a need for improvement. Consider: the large grinding stock used to compensate for heat treatment distortion can significantly reduce manufacturing productivity; and, materials and manufacturing processes are two other promising avenues to improvement. The work presented here investigates quenchable alloy steels that, combined with specifically developed Case-hardening and heat treatment processes, exhibits reduced distortion and, in turn, requires a smaller grinding stock.

114 Surface Pitting Fatigue Life of Noninvolute Low-Contact-Ratio Gears (May/June 1991)

Spur gear endurance tests were conducted to investigate the surface pitting fatigue life of noninvolute gears with low numbers of teeth and low contact ratios for the use in advanced application. The results were compared with those for a standard involute design with a low number of teeth. The gear pitch diameter was 8.89 cm (3.50 in.) with 12 teeth on both gear designs. Test conditions were an oil inlet temperature of 320 K (116 degrees F), a maximum Hertz stress of 1.49 GPa (216 ksi), and a speed of 10,000 rpm. The following results were obtained: The noninvolute gear had a surface pitting fatigue life approximately 1.6 times that of the standard involute gear of a similar design. The surface pitting fatigue life of the 3.43-pitch AISI 8620 noninvolute gear was approximately equal to the surface pitting fatigue life of an 8-pitch, 28-tooth AISI 9310 gear at the same load, but at a considerably higher maximum Hertz stress.

115 Influence of Relative Displacements Between Pinion and Gear on Tooth Root Stresses of Spiral Bevel Gears (July/August 1985)

The manufacturing quality of spiral bevel gears has achieved a very high standard. Nevertheless, the understanding of the real stress conditions and the influences. of certain parameters is not satisfactory.

116 Innovative Concepts for Grinding Wind Power Energy Gears (June 2009)

This article shows the newest developments to reduce overall cycle time in grinding wind power gears, including the use of both profile grinding and threaded wheel grinding.

117 Relationship Between Wear and Pitting Phenomena in Worm Gears (May/June 1998)

Worm gears display unique behavior of surfaces because of the presence of wear phenomena in addition to contact pressure phenomena.

118 Dry Cutting of Bevel and Hypoid Gears (May/June 1998)

High-speed machining using carbide has been used for some decades for milling and turning operations. The intermittent character of the gear cutting process has delayed the use of carbide tools in gear manufacturing. Carbide was found at first to be too brittle for interrupted cutting actions. In the meantime, however, a number of different carbide grades were developed. The first successful studies in carbide hobbing of cylindrical gears were completed during the mid-80s, but still did not lead to a breakthrough in the use of carbide cutting tools for gear production. Since the carbide was quite expensive and the tool life was too short, a TiN-coated, high-speed steel hob was more economical than an uncoated carbide hob.

119 Tooth Root Stresses of Spiral Bevel Gears (May/June 1988)

Service performance and load carrying capacity of bevel gears strongly depend on the size and position of the contact pattern. To provide an optimal contact pattern even under load, the gear design has to consider the relative displacements caused by deflections or thermal expansions expected under service conditions. That means that more or less lengthwise and heightwise crowning has to be applied on the bevel gear teeth.

120 Repair of Large, Surface-Degraded Industrial Gears - a New Approach (January/February 2017)

This paper presents a new approach to repair industrial gears by showing a case study where pressure angle modification is also considered, differently from the past repairing procedures that dealt only with the modification of the profile shift coefficient. A computer program has been developed to automatically determine the repair alternatives under two goals: minimize the stock removal or maximize gear tooth strength.

121 Designing Hardened & Ground Spur Gears to Operate With Minimum Noise (May/June 1994)

When designing hardened and ground spur gears to operate with minimum noise, what are the parameters to be considered? should tip and/or root relief be applied to both wheel and pinion or only to one member? When pinions are enlarged and he wheel reduced, should tip relief be applied? What are the effects on strength, wear and noise? For given ratios with enlarged pinions and reduced wheels, how can the gear set sized be checked or adjusted to ensure that the best combination has been achieved?

122 Idler Gears (May 2016)

What is the point of using two idler gears in a geartrain?

123 Design and Optimization of Planetary Gears Considering All Relevant Influences (November/December 2013)

Light-weight construction and consideration of available resources result in gearbox designs with high load capacity and power density. At the same time, expectations for gear reliability are high. Additionally, there is a diversity of planetary gears for different applications.

124 The Use of Boundary Elements For The Determination of the AGMA Geometry Factor (January/February 1988)

The geometry factor, which is a fundamental part of the AGMA strength rating of gears, is currently computed using the Lewis parabola which allows computation of the Lewis form factor.(1) The geometry factor is obtained from this Lewis factor and load sharing ratio. This method, which originally required graphical construction methods and more recently has been computerized, works reasonably well for external gears with thick rims.(2-6) However, when thin rims are encountered or when evaluating the strength of internal gears, the AGMA method cannot be used.

125 Cylkro Face Gears (November/December 2010)

Dutch design and Swiss ingenuity cause transmission breakthrough. Updated examples of Cylkro face gears in action.

126 Marine Gears: Special Aspects for High Performance (May/June 2006)

A gearbox that absorbs 30 percent of external forces, transmits power from two engines operating at different speeds, and uses gears that meet several design and specification standards at the same time...

127 Cutting Worm Gears with Standard Gear Hobs (January/February 1994)

We make a lot of single-start worm and worm gear sets, and it always seems as though we're buying another special hob. We also do a lot of spur gear cutting, and the spur gear hobs and the worm gear hobs look alike, so we wonder why we cannot use the standard hobs for cutting worm gears too. Can we do this?

128 Down By The Old Mill Stream (March/April 1997)

Back in the days when our great, great, great, etc., grandaddies were designing gears, one of the most common materials in use was wood. For fairly obvious reasons, we don't see too many wooden gears around anymore. But there are a few.

129 Coated Gears Provide Slick Solution for Human-Powered Boat (January/February 1997)

Design Problem: Develop a gear drive for a pedal-powered water craft that will be easy to manufacture, use and maintain; that will be lightweight enough for the boat to be portable; and that will eliminate the environmental risk of lubricants leaking into the water.

130 Minimizing Gear Distortion During Heat Treating (March/April 1996)

Graded hardening technology has proven over the years to yield very good results when used in the heat treating of carburized gears. It is especially advantageous for smaller companies, subject to higher competitive pressures. Unfortunately, despite the fact that graded hardening is a very well-known method, its use has been limited. We strongly recommend this technology to all of those who need to produce gears with high metallurgical quality.

131 Good Basic Design or Sophisticated Flank Optimizations - Each at the Right Time (January/February 2005)

More strength, less noise. Those are two major demands on gears, including bevel and hypoid gears.

132 Minimizing Backlash in Spur Gears (May/June 1994)

simplified equations for backlash and roll test center distance are derived. Unknown errors in measured tooth thickness are investigate. Master gear design is outlined, and an alternative to the master gear method is described. Defects in the test radius method are enumerated. Procedures for calculating backlash and for preventing significant errors in measurement are presented.

133 Gear mesh, NVH Evaluation (June 2015)

The question is quite broad, as there are different methods for setting various types of gears and complexity of gear assemblies, but all gears have a few things in common.

134 Introduction to Worm Gearing (March/April 1993)

Worm gears are among the oldest types of gearing, but that does not mean they are obsolete, antiquated technology. The main reasons for the bad experiences some engineers have with worm gearing are misapplication and misuse. No form of gearing works for every application. Strengths and weaknesses versus the application must be weighed to decide which form of gearing to use. For proper application and operation of worm gears, certain areas that may differ from other types of gearing need to be addressed.

135 Gear Grinding Comes of Age (July/August 1995)

In the quest for ever more exacting and compact commercial gears, precision abrasives are playing a key production role - a role that can shorten cycle time, reduce machining costs and meet growing market demand for such requirements as light weights, high loads, high speed and quiet operation. Used in conjunction with high-quality grinding machines, abrasives can deliver a level of accuracy unmatched by other manufacturing techniques, cost-effectively meeting AGMA gear quality levels in the 12 to 15 range. Thanks to advances in grinding and abrasive technology, machining has become one of the most viable means to grind fast, strong and quiet gears.

136 How to Avoid Errors When Measuring Step Gears (July/August 1995)

There are problems in dimensional measurement that should be simple to solve with standard measuring procedures, but aren't. In such cases, using accepted practices may result in errors of hundreds of microns without any warning that something is wrong.

137 Gears Around the World (Wide Web) (July/August 1996)

More Gears in Cyberspace Dial in to the web site of Chicago's Museum of Science and Industry for an online version of the museum's Gears from the Century of Progress exhibit.

138 Profile Grinding Gears From The Solid - Is It Practical (May/June 1997)

It isn't for everyone, but... Within the installed base of modern CNC gear profile grinding machines (approximately 542 machines worldwide), grinding from the solid isn't frequent, but a growing number of gear profile grinder users are applying it successfully using CBN-plated wheels.

139 The Next Step in Bevel Gear Metrology (January/February 1996)

In recent years, gear inspection requirements have changed considerably, but inspection methods have barely kept pace. The gap is especially noticeable in bevel gears, whose geometry has always made testing them a complicated, expensive and time-consuming process. Present roll test methods for determining flank form and quality of gear sets are hardly applicable to bevel gears at all, and the time, expense and sophistication required for coordinate measurement has limited its use to gear development, with only sampling occurring during production.

140 Effect of Web & Flange Thickness on Nonmetallic Gear Performance (November/December 1995)

Gears are manufactured with thin rims for several reasons. Steel gears are manufactured with thin rims and webs where low weight is important. Nonmetallic gears, manufactured by injection molding, are designed with thin rims as part of the general design rule to maintain uniform thickness to ensure even post-mold cooling. When a thin-rimmed gear fails, the fracture is thought the root of the gear, as shown in Fig. 1a, rather than the usual fillet failure shown in Fig. 1b.

141 The Bridges of Cook County and Other Sagas (September/October 1996)

In spite of being the "Second City," Chicago has always cultivated a reputation for bigness. We're known for big talk, big shoulders, big basketball players - and big gears. While not necessarily the biggest in the world (more about that late), some Chicago gears are among the hardest working.

142 Increased Tooth Bending Strength and Pitting Load Capacity of Fine-Module Gears (September/October 2016)

The common calculation methods according to DIN 3990 and ISO 6336 are based on a comparison of occurring stress and allowable stress. The influence of gear size on the load-carrying capacity is considered with the size factors YX (tooth root bending) and ZX (pitting), but there are further influences, which should be considered. In the following, major influences of gear size on the load factors as well as on the permissible tooth root bending and contact stress will be discussed.

143 New Standards for Large Ring Gears for Mills, Kilns (September 2013)

Methods of examining large ring gear teeth to detect surface breaking discontinuities have often been time-consuming and limited in terms of data collected. Methods such as visual and magnetic particle inspection can miss critical discontinuities. However, a new ASTM international standard provides a more effective method for gear examination using eddy current array, a technology that has been widely used but, until now, not standardized.

144 Rules for Optimal Basic Design of Bevel Gears (May 2016)

Bevel Gear Technology Chapter 6

145 Magnetic Gears, Sleeping Giant or Toothless Tiger (November/December 2013)

When is a gear not a gear? Pardon my Zen, but that is a bit like asking, "What is the sound of one hand clapping?" Or there’s the old bromide, "If it walks like a duck, talks like a duck," etc. Just work with me here…

146 An Experimental Investigation of Aerospace-Quality Gears Operating in Loss-of-Lubrication Condition (August 2013)

This work establishes a baseline for aerospace spur gear behavior under oil-off conditions. The collected test results document a different oil-off time, dictated by material used.

147 New Methods for the Calculation of the Load Capacity of Bevel and Hypoid Gears (June/July 2013)

Flank breakage is common in a number of cylindrical and bevel gear applications. This paper introduces a relevant, physically based calculation method to evaluate flank breakage risk vs. pitting risk. Verification of this new method through testing is demonstrably shown.

148 Light Weight Assembled Gears - A Green Design Solution (May 2013)

It is widely recognized that the reduction of CO2 requires consistent light-weight design of the entire vehicle. Likewise, the trend towards electric cars requires light-weight design to compensate for the additional weight of battery systems. The need for weight reduction is also present regarding vehicle transmissions. Besides the design of the gearbox housing, rotating masses such as gear wheels and shafts have a significant impact on fuel consumption. The current technology shows little potential of gear weight reduction due to the trade-off between mass optimization and the manufacturing process. Gears are usually forged followed or not by teeth cutting operation.

149 Off-Highway Gears (June/July 2013)

Market needs push in 2013, but will it get one? The construction/off-highway industries have been here before. New equipment, technologies and innovations during an economic standstill that some have been dealing with since 2007.

150 Super-Sized Quality Control (January/February 2014)

It's not easy being big. Maybe that's not exactly how the phrase goes, but it's applicable, particularly when discussing the quality requirements of large gears. The size alone promises unique engineering challenges. BONUS Online Exclusive: Big or Small - Inspection is Key to Success.

151 Hard-Finishing Spiral Bevel Gears (March/April 2016)

Could you explain to me the difference between spiral bevel gear process face hobbing-lapping, face milling-grinding and Klingelnberg HPG? Which one is better for noise, load capacity and quality?

152 An Investigation of the Influence of Shaft Misalignment on Bending Stresses of Helical Gears with Lead Crown (November/December 2008)

In this study, the combined influence of shaft misalignments and gear lead crown on load distribution and tooth bending stresses is investigated. Upon conclusion, the experimental results are correlated with predictions of a gear load distribution model, and recommendations are provided for optimal lead crown in a given misalignment condition.

153 Gear Mathematics for Bevel & Hypoid Gears (August 2015)

The calculation begins with the computation of the ring gear blank data. The geometrically relevant parameters are shown in Figure 1. The position of the teeth relative to the blank coordinate system of a bevel gear blank is satisfactorily defined with...

154 Test Facility Simulation Results for Aerospace Loss-of-Lubrication of Spur Gears (June 2015)

Prior to receiving airworthiness certification, extensive testing is required during the development of rotary wing aircraft drive systems. Many of these tests are conducted to demonstrate the drive system’s ability to operate at extreme conditions, i.e. — beyond that called for in the normal to maximum power operating range.

155 Small-Module Gear Design (November/December 2014)

Gears with a diametral pitch 20 and greater, or a module 1.25 millimeters and lower, are called fine-pitch or low-module gears. The design of these gears has its own specifics.

156 Less Energy Consumption with High-Efficiency Bevel Gears and their Usage in the U.S. (September/October 2014)

The efficiency of a gearbox is the output energy divided by the input energy. It depends on a variety of factors. If the complete gearbox assembly in its operating environment is observed, then the following efficiency influencing factors have to be considered

157 The Importance of Profile Shift, Root Angle Correction and Cutter Head Tilt (January/February 2016)

Chapter 2, Continued In the previous sections, development of conjugate, face milled — as well as face hobbed — bevel gearsets — including the application of profile and length crowning — was demonstrated. It was mentioned during that demonstration that in order to optimize the common surface area, where pinion and gear flanks have meshing contact (common flank working area), a profile shift must be introduced. This concluding section of chapter 2 explains the principle of profile shift; i.e. — how it is applied to bevel and hypoid gears and then expands on profile side shift, and the frequently used root angle correction which — from its gear theoretical understanding — is a variable profile shift that changes the shift factor along the face width. The end of this section elaborates on five different possibilities to tilt the face cutter head relative to the generating gear, in order to achieve interesting effects on the bevel gear flank form. This installment concludes chapter 2 of the Bevel Gear Technology book that lays the foundation of the following chapters, some of which also will be covered in this series.

158 Technological Potential and Performance of Gears Ground by Dressable CBN Tools (March/April 2014)

Dressable vitrified bond CBN grinding tools combine the advantages of other common tool systems in generating gear grinding. Yet despite those technological advantages, there is only a small market distribution of these grinding tools due to high tool costs. Furthermore, scant literature exists regarding generating gear grinding with dressable CBN. This is especially true regarding the influence of the grinding tool system on manufacturing-related component properties. The research objective of this report is to determine the advantages of dressable CBN tools in generating gear grinding.

159 Mobilizing Microgears (July 2016)

We’ve been in the business of making things small and portable for a long time. But when it comes to shrinking things down, a team of scientists from Germany, Italy and Spain led by Roberto Di Leonardo decided to go big.

160 Large Pinions for Open Gears - The Increase of Single Mesh Load (January/February 2013)

This paper introduces mandatory improvements in design, manufacturing and inspection - from material elaboration to final machining - with special focus on today's large and powerful gearing.

161 Influence of Topography Deviations on the Psychoacoustic Evaluation of Ground Bevel Gears (November/December 2016)

In the design process of transmissions, one major criterion is the resulting noise emission of the powertrain due to gear excitation. Within the past years, much investigation has shown that the noise emission can be attributed to quasi-static transmission error. Therefore, the transmission error can be used for a tooth contact analysis in the design process, as well as a characteristic value for quality assurance by experimental inspections.

162 A Practical Guide for Molding Better Plastic Geared Transmissions (May/June 2000)

Plastic gears and transmissions require a different design approach than metal transmissions. Different tools are available to the plastic transmission designer for optimizing his geared product, and different requirements exist for inspection and testing. This paper will present some of the new technology available to the plastic gear user, including design, mold construction, inspection, and testing of plastic gears and transmissions.

163 Gear Failure Analysis Involving Grinding Burn (January/February 2009)

When gears are case-hardened, it is known that some growth and redistribution of stresses that result in geometric distortion will occur. Aerospace gears require post case-hardening grinding of the gear teeth to achieve necessary accuracy. Tempering of the case-hardened surface, commonly known as grinding burn, occurs in the manufacturing process when control of the heat generation at the surface is lost.

164 Effects of Planetary Gear Ratio on Mean Service Life (July/August 1998)

Planetary gear transmissions are compact, high-power speed reducers that use parallel load paths. The range of possible reduction ratios is bounded from below and above by limits on the relative size of the planet gears. For a single-plane transmission, the planet gear has no size of the sun and ring. Which ratio is best for a planetary reduction can be resolved by studying a series of optimal designs. In this series, each design is obtained by maximizing the service life for a planetary transmission with a fixed size, gear ratio, input speed, power and materials. The planetary gear reduction service life is modeled as a function of the two-parameter Weibull distributed service lives of the bearings and gears in the reduction. Planet bearing life strongly influences the optimal reduction lives, which point to an optimal planetary reduction ratio in the neighborhood of four to five.

165 Plastic: The Not-So-Alternative Technology (July/August 1998)

"We're taking over," says Art Milano. It's a bold statement from the engineering manager of Seitz Corporation, one of the largest manufacturers of injection molded plastic gears, but Milano has reason for his optimism. Plastic gears are big business-probably bigger than most gear industry "insiders" realize.

166 Gears In Sneakers (September/October 1997)

Move over, Michael Jordan. While the Addendum staff is as proud as any other Chicagoans of our unbeata-Bulls, we confess to a soft spot in our hearts for the hometown's other championship basketball team: The Chicago American Gears.

167 New Guideless CNC Shaper for Helical Gears (March/April 1998)

Product announcements so often trumpet minor, incremental advances with works like "revolutionary" and "unique" that even the best thesaurus can fail to offer a fresh alternative to alert the reader when something really innovative and important is introduced. In the case of Mitsubishi's new CNC gear shaper, the ST25CNC, both terms apply.

168 Parallel Axis Gear Grinding: Theory & Application (November/December 2000)

The goal of gear drive design is to transit power and motion with constant angular velocity. Current trends in gear drive design require greater load carrying capacity and increased service life in smaller, quieter, more efficient gearboxes. Generally, these goals are met by specifying more accurate gears. This, combined with the availability of user-friendly CNC gear grinding equipment, has increased the use of ground gears.

169 Cutting Low-Pitch-Angle Bevel Gears, Worm Gears and The Oil Entry Gap (July/August 1992)

Question: Do machines exist that are capable of cutting bevel gear teeth on a gear of the following specifications: 14 teeth, 1" circular pitch, 14.5 degrees pressure angle, 4 degrees pitch cone angle, 27.5" cone distance, and an 2.5" face width?

170 Pitting Resistance of Worm Gears: Advanced Model for Contact Pattern of Any Size, Position, Flank Type (October 2012)

An experimental and theoretical analysis of worm gear sets with contact patterns of differing sizes, position and flank type for new approaches to calculation of pitting resistance.

171 How to Achieve a Successful Molded Gear Transmission (July/August 2006)

Molded plastic gears have very little in common with machined gears other than the fact that both use the involute for conjugate action.

172 Gears without Standards - But Tons of Fun! (November/December 2012)

If you enjoy working with your hands—without doubt a large segment of Gear Technology’s audience—you must go to There you will find one of the most clean-but-serious fun websites on the Internet. It is where you will learn—or re-learn, in some cases—how to create things from paper. Origami, you’re thinking? Nah—mere child’s play.

173 New Technology for Stronger Plastic Gears (August 2012)

Gleason-K2 Plastics eliminates weld lines with no machining.

174 Stress of Planet Gears with Thin Rims (March/April 1994)

This article discusses the relationships among the fillet stress on a thin rim planet gear, the radial clearance between the gear rim and the gear shaft, the tooth load, the rim thickness, the radius of curvature of the center line of the rim, the face width and the module.

175 Characteristics of Master Gears (November/December 2006)

The two-flank roll test measures kickout (tooth-to-tooth composite error) and tooth thickness. In this article, it will be shown that measured values vary with the number of teeth on the master gear.

176 Longitudinal Tooth Contact Pattern Shift (May 2012)

After a period of operation, high-speed turbo gears may exhibit a change in longitudinal tooth contact pattern, reducing full face width contact and thereby increasing risk of tooth distress due to the decreased loaded area of the teeth. But this can be tricky—the phenomenon may or may not occur. Or, in some units the shift is more severe than others, with documented cases in which shifting occurred after as little as 16,000 hours of operation. In other cases, there is no evidence of any change for units in operation for more than 170,000 hours. This condition exists primarily in helical gears. All recorded observations here have been with case-carburized and ground gear sets. This presentation describes phenomena observed in a limited sampling of the countless high-speed gear units in field operation. While the authors found no existing literature describing this behavior, further investigation suggests a possible cause. Left unchecked and without corrective action, this occurrence may result in tooth breakage.

177 Hoechst Technical Polymers to Gather Plastic Gear Materials Data (July/August 1997)

Hoechst Technical Polymers has expanded its interests in plastic gears with the introduction of the new Plastic Gear Evaluation and Research machine P-Gear. The machine is the centerpiece of the company's continuing efforts to promote and develop the use of plastic gears in higher-powered applications.

178 Effect of Extended Tooth Contact on the Modeling of Spur Gear Transmissions (July/August 1994)

In some gear dynamic models, the effect of tooth flexibility is ignored when the model determines which pairs of teeth are in contact. Deflection of loaded teeth is not introduced until the equations of motion are solved. This means the zone of tooth contact and average tooth meshing stiffness are underestimated, and the individual tooth load is overstated, especially for heavily loaded gears. This article compares the static transmission error and dynamic load of heavily loaded, low-contact-ratio spur gears when the effect of tooth flexibility has been considered and when it has been ignored. Neglecting the effect yields an underestimate of resonance speeds and an overestimate of the dynamic load.

179 Weird Science (June 2010)

Who knew what a few hundred bacteria could do with a little cooperation? Andrey Sokolov of Princeton University, Igor Aronson from the Argonne National Laboratory and Bartosz Grzybowski and Mario Apodaca from Northwestern University found out after placing microgears (380 microns long with slanted spokes) in a solution with the common aerobic bacteria Bacillus subtilis. The scientists observed that the bacteria appeared to swim randomly but occasionally collided with the spokes of the gears and turned them.

180 Engineering Constants (May/June 1987)

Rules and Formula for worm gears, bevel gears and strength of gear teeth.

181 Carburizing of Big Module and Large Diameter Gears (September/October 2002)

Carburized gears have higher strengths and longer lives compared with induction-hardened or quench-tempered gears. But in big module gears, carburizing heat-treatment becomes time-consuming and expensive and sometimes cannot achieve good hardness due to the big mass-effect. Also, it is not easy to reduce distortion of gears during heat treatment.

182 A Logical Procedure To Determine Initial Gear Size (November/December 1986)

When a gear set is to be designed for a new application, the minimum size gears with the required capacity are desired. These gears must be capable of meeting the power, speed, ratio, life, and reliability requirements.

183 Forget the View...Check Out Those Gears! (June 2007)

On May 20, the city of Pittsburgh celebrated the 130th anniversary of the Duquesne Incline, a funicular railway that allows passengers to travel via cable car to an observation area and catch a panoromic view of the city and—most importantly—get a bird’s eye glimpse of the gear teeth in action.

184 Plastic Gears--A Growing Industry Still Seeking Respect (March/April 2007)

Forty years ago, the plastics industry was practically in its embryonic phase...

185 A Model of the Pumping Action Between the Teeth of High-Speed Spur and Helical Gears (May/June 2004)

For a high-speed gearbox, an important part of power losses is due to the mesh. A global estimation is not possible and an analytical approach is necessary with evaluations of three different origins of power losses: friction in mesh contact, gear windage and pumping effect between teeth.

186 Describing Nonstandard Gears - An Alternative to the Rack Shift Coefficient (January/February 1988)

The use of dimensionless factors to describe gear tooth geometry seems to have a strong appeal to gear engineers. The stress factors I and J, for instance, are well established in AGMA literature. The use of the rack shift coefficient "x" to describe nonstandard gear proportions is common in Europe, but is not as commonly used in the United States. When it is encountered in the European literature or in the operating manuals for imported machine tools, it can be a source of confusion to the American engineer.

187 Improved Worm Gear Performance with Colloidal Molybdenum Disulfide Containing Lubricants (November/December 1988)

Worm gear speed reducers give the design engineer considerable options, but these gear systems present a challenge to the lubrication engineer. Heat energy generated by the high rate of sliding and friction in the contact zone causes worm gears to be relatively inefficient compared to other gear types. Because worm gears operate under a boundary or near-boundary lubrication regime, a satisfactory lubricant should contain a friction modifier to alleviate these conditions.

188 Spur Gear Fundamentals (January/February 1989)

Gears are toothed wheels used primarily to transmit motion and power between rotating shafts. Gearing is an assembly of two or more gears. The most durable of all mechanical drives, gearing can transmit high power at efficiencies approaching 0.99 and with long service life. As precision machine elements gears must be designed.

189 Thermal Behavior of Helical Gears (May 2007)

An experimental effort has been conducted on an aerospace-quality helical gear train to investigate the thermal behavior of the gear system as many important operational conditions were varied.

190 Sizing Up Big Gears (January/February 2010)

Quality, materials and technology continue to challenge the big gear manufacturing market.

191 Curvilinear Cylindrical Gears (May/June 1988)

The curved tooth cylindrical gear is one of ancient design. Samples which date from the period of the Warring State (475-221 BC) have been excavated from archeological sites in China. One such sample is now on display in the Xi'an Clay figures of Warriors and Horses Exhibition Hall. This example is about 3/4" in diameter and made of bronze. It was used in the famous model, "Ancient Chinese Vehicle With a Wooden Figure Always Pointing to the South." Although this early gear is handmade and somewhat crude, it is a viable model.

192 Straight Bevel Gears (September/October 2010)

Tribology Aspects in Angular Transmission Systems, Part 2

193 Gears for Nonparallel Shafts (September/October 1986)

Transmission of power between nonparallel shafts is inherently more difficult than transmission between parallel shafts, but is justified when it saves space and results in more compact, more balanced designs. Where axial space is limited compared to radial space, angular drives are preferred despite their higher initial cost. For this reason, angular gear motors and worm gear drives are used extensively in preference to parallel shaft drives, particularly where couplings, brakes, and adjustable mountings add to the axial space problem of parallel shaft speed reducers.

194 Micropitting of Big Gearboxes: Influence of Flank Modification and Surface Roughness (May 2011)

Most research on micropitting is done on small-sized gears. This article examines whether those results are also applicable to larger gears.

195 Assembling Spiral Gears: Double Taper Can Be Double Trouble (January/February 2006)

Bevel gear systems are particularly sensitive to improper assembly. Slight errors in gear positioning can turn a well-designed, quality manufactured gear set into a noisy, prone-to-failure weak link in your application.

196 Worm Gears - Higher Energy Efficiency and Less Strain on Resources (May 2011)

A very direct and effective way of increasing power transmission efficiency is a changeover from mineral-oil-based lubricants to synthetic lubricants.

197 Tribology Aspects in Angular Transmission Systems, Part V: Face Gears (March/April 2011)

This article is part five of an eight-part series on the tribology aspects of angular gear drives. Each article will be presented first and exclusively by Gear Technology, but the entire series will be included in Dr. Stadtfeld’s upcoming book on the subject, which is scheduled for release in 2011.

198 Spiral Bevel Gears: Tribology Aspects in Angular Transmission Systems, Part IV (January/February 2011)

This article is part four of an eight-part series on the tribology aspects of angular gear drives. Each article will be presented first and exclusively by Gear Technology, but the entire series will be included in Dr. Stadtfeld’s upcoming book on the subject, which is scheduled for release in 2011.

199 Kinematical Simulation of Face Hobbing Indexing and Tooth Surface Generation of Spiral Bevel and Hypoid Gears (January/February 2006)

In addition to the face milling system, the face hobbing process has been developed and widely employed by the gear industry. However, the mechanism of the face hobbing process is not well known.

200 Application of Gears with Asymmetric Teeth in Turboprop Engine Gearbox (January/February 2008)

This paper describes the research and development of the first production gearbox with asymmetric tooth profiles for the TV7-117S turboprop engine. The paper also presents numerical design data related to development of this gearbox.

201 Face Gears: Geometry and Strength (January/February 2007)

There are three distinct gear types in angle drives. The most commonly used are bevel and worm drives. Face gear drives are the third alternative.

202 Bevel Gear Development and Testing Procedure (July/August 1986)

The most conclusive test of bevel and hypoid gears is their operation under normal running conditions in their final mountings. Testing not only maintains quality and uniformity during manufacture, but also determines if the gears will be satisfactory for their intended applications.

203 Economics of CNC Gear Gashing vs. Large D.P. Hobbing (August/September 1984)

Gear gashing is a gear machining process, very much like gear milling, utilizing the principle of cutting one or more tooth (or tooth space) at a time. The term "GASHING" today applies to the roughing, or roughing and finishing, of coarse diametral pitch gears and sprockets. Manufacturing these large coarse gears by conventional methods of rough and finish hobbing can lead to very long machining cycles and uneconomical machine utilization.

204 Low Loss Gears (June 2007)

In most transmission systems, one of the main power loss sources is the loaded gear mesh. In this article, the influences of gear geometry parameters on gear efficiency, load capacity, and excitation are shown.

205 Getting a Grip on Big-Gear Lubrication (January/February 2012)

In the wide, wide world of moving parts, the gears required for the big jobs—the really big jobs—often experience big problems. Proper lubrication of these gears is paramount in industrial applications such as wind turbines, kilns, sugar mills, crushers, heavy construction, offshore drilling rigs, mining and quarrying.

206 On The Interference of Internal Gearing (July/August 1989)

Since size and efficiency are increasingly important considerations in modern machinery, the trend is gear design is to use planetary gearing instead of worm gearing and multi-stage gear boxes. Internal gearing is an important part of most of planetary gear assemblies. In external gearing, if the gears are standard (of no-modified addenda), interference rarely happens. But in an internal gearing, especially in some new types of planetary gears, such as the KHV planetary, the Y planetary, etc., (1) various types of interference may occur. Therefore, avoiding interference is of significance for the design of internal gearing.

207 The Effect of Reverse Hobbing at a High Speed (March/April 1987)

Today it is common practice when climb hobbing to keep the direction of the hob thread the same as that of the helical gear. The same generalization holds true for the mass production of gears for automobiles. It is the authors' opinion, however, that conventional hobbing with a reverse-handed hob is more effective for the high-speed manufacture of comparatively small module gears for automobiles. The authors have proven both experimentally and theoretically that reverse-handed conventional hobbing, using a multi-thread hob with a smaller diameter is very effective for lengthening the life of the hob and for increasing cutting efficiency at high speeds.

208 Design Guidelines for High-Capacity Bevel Gear Systems (January/February 1992)

The design of any gearing system is a difficult, multifaceted process. When the system includes bevel gearing, the process is further complicated by the complex nature of the bevel gears themselves. In most cases, the design is based on an evaluation of the ratio required for the gear set, the overall envelope geometry, and the calculation of bending and contact stresses for the gear set to determine its load capacity. There are, however, a great many other parameters which must be addressed if the resultant gear system is to be truly optimum. A considerable body of data related to the optimal design of bevel gears has been developed by the aerospace gear design community in general and by the helicopter community in particular. This article provides a summary of just a few design guidelines based on these data in an effort to provide some guidance in the design of bevel gearing so that maximum capacity may be obtained. The following factors, which may not normally be considered in the usual design practice, are presented and discussed in outline form: Integrated gear/shaft/bearing systems Effects of rim thickness on gear tooth stresses Resonant response

209 Bending Fatigue, Impact and Pitting Resistance of Ausform-Finished PM Gears (June 2010)

The powder metal (P/M) process is making inroads in automotive transmission applications due to substantially lower costs of P/M-steel components for high-volume production, as compared to wrought or forged steel parts. Although P/M gears are increasingly used in powered hand tools, gear pumps and as accessory components in automotive transmissions, P/M-steel gears are currently in limited use in vehicle transmission applications. The primary objective of this project was to develop high-strength P/M-steel gears with bending fatigue, impact resistance and pitting fatigue performance equivalent to current wrought steel gears.

210 Flank Breakage on Gears for Energy Systems (November/December 2011)

Gear flank breakage can be observed on edge zone-hardened gears. It occurs, for example, on bevel gears for water turbines, on spur gears for wind energy converters and on single- and double-helical gears for other industrial applications.

211 Gear Grinding Techniques Parallel Axes Gears (March/April 1985)

The fundamental purpose of gear grinding is to consistently and economically produce "hard" or "soft" gear tooth elements within the accuracy required by the gear functions. These gear elements include tooth profile, tooth spacing, lead or parallelism, axial profile, pitch line runout, surface finish, root fillet profile, and other gear geometry which contribute to the performance of a gear train.

212 Latest Generation of Quieter Plastic Gears Can Take the Heat (November/December 2005)

Ten years ago, most mainstream gear manufacturers didn't even consider plastics as an option, especially in higher power applications.

213 Laminated Gearing (November/December 2005)

Laminated spur gears with one-tooth pinions can be an alternative to spur gears.

214 Effect of MoS2 Films on Scoring Resistance of Gears (July/August 1986)

Gears are currently run at high speed and under high load. It is a significant problem to develop lubricants and gears with high load-carrying capacity against scoring. The particles of molybdenum disulfide have been considered to increase the scoring resistance of the gears. The wear characteristics and the scoring resistance of the gears lubricated with MoS2 paste and MoS2 powder have been investigated. (1) However, there are few investigations on the performance of the gears coated with MoS2 film with respect to scoring.

215 Refurbishing a Ball Mill ; Bevel Gear Backlash (September 2012)

Our experts comment on reverse engineering herringbone gears and contact pattern optimization.

216 Industry Forum (July/August 1985)

In response to Ed Uberts letter, we have come a long way in gearing since WWII. The Europeans do use long addendum pinions in many cases. This modification does improve load capacity, sliding conditions and the working life of a gearset. When modifying a pinion tooth it is necessary to modify the gear tooth or adjust the center distance accordingly but we will leave that to the designers.

217 Evaluation of a Low-Noise, Formate Spiral Bevel Gear Set (January/February 2008)

Studies to evaluate low-noise Formate spiral bevel gears were performed. Experimental tests were conducted on a helicopter transmission test stand...

218 Ask the Expert - Bevel Gear Mounting (March/April 2012)

I am currently writing a design procedure for the correct method for setting up bevel gears in a gearbox for optimum performance...

219 Large Scores and Radial Cracks on Case-Hardened Worms (May/June 2003)

In the last couple of years, many research projects dealt with the determination of load limits of cylindrical worm gears. These projects primarily focused on the load capacity of the worm wheel, whereas the worm was neglected. This contribution presents investigations regarding damages such as large scores and cracks on the flanks of case-hardened worms.

220 Gear Damage Detection Using Oil Debris Analysis (January/February 2003)

The purpose of this paper was to verify, when using an oil debris sensor, that accumulated mass predicts gear pitting damage and to identify a method to set threshold limits for damaged gears.

221 Maximum Surface Temperature of the Thermoplastic Gear in a Non-Lubricated Plastic-Steel Gear Pair (August/September 1984)

One of the major problems of plastic gear design is the knowledge of their running temperature. Of special interest is the bulk temperature of the tooth to predict the fatigue life, and the peak temperature on the surface of the tooth to avert surface failure. This paper presents the results of an experimental method that uses an infrared radiometer to measure the temperature variation along the profile of a plastic gear tooth in operation. Measurements are made on 5.08, 3.17, 2.54, 2.12 mm module hob cut gears made from nylon 6-6, acetal and UHMWPE (Ultra High Molecular Weight Polyethylene). All the tests are made on a four square testing rig with thermoplastic/steel gear pairs where the plastic gear is the driver. Maximum temperature prediction curves obtained through statistical analysis of the results are presented and compared to data available from literature.

222 Gear Milling on Non-Gear Dedicated Machinery (July 2009)

Imagine the flexibility of having one machine capable of milling, turning, tapping and gear cutting with deburring included for hard and soft material. No, you’re not in gear fantasy land. The technology to manufacture gears on non gear-dedicated, mult-axis machines has existed for a few years in Europe, but has not yet ventured into mainstream manufacturing. Deckel Maho Pfronten, a member of the Gildemeister Group, took the sales plunge this year, making the technology available on most of its 2009 machines.

223 Helical Gear Systems (August 2016)

In terms of the tooth thickness, should we use the formulation with respect to normal or transverse coordinate system? When normalizing this thickness in order to normalize the backlash (backlash parameter), we should divide by the circular pitch. Thus, when normalizing, should this circular pitch be defined in the normal or traverse coordinate system, depending on which formulation has been used? Is the backlash parameter always defined with respect to the tangential plane or normal plane for helical gears?

224 Winds of Change in Profile Grinding (May/June 2004)

Recent breakthroughs in profile grinding software are helping Anderson Precision Gears and others meet wind power’s insatiable appetite for faster production of large, high-quality gears.

225 How to Minimize Power Losses in Transmissions, Axles and Steering Systems (September 2012)

By increasing the number of gears and the transmission-ratio spread, the engine will run with better fuel efficiency and without loss of driving dynamics. Transmission efficiency itself can be improved by: using fuelefficient transmission oil; optimizing the lubrication systems and pumps; improving shifting strategies and optimizing gearings; and optimizing bearings and seals/gaskets.

226 Spiral Bevel Gear Development: Elminiating Trial and Error with Computer Technology (January/February 2003)

Computer technology has touched all areas of our lives, impacting how we obtain airline tickets, purchase merchandise and receive medical advice. This transformation has had a vast influence on manufacturing as well, providing process improvements that lead to higher quality and lower costs. However, in the case of the gear industry, the critical process of tooth contact pattern development for spiral bevel gears remains relatively unchanged.

227 Beachfront Gear Manufacturing (January/February 2007)

Lots of us became interested in gears while taking drafting classes in high school.

228 Low-Distortion Heat Treatment of Transmission Components (October 2011)

This paper presents how low pressure carburizing and high pressure gas quenching processes are successfully applied on internal ring gears for a six-speed automatic transmission. The specific challenge in the heat treat process was to reduce distortion in such a way that subsequent machining operations are entirely eliminated.

229 Hybrid Gear Preliminary Results: Application of Composites to Dynamic Mechanical Components (May 2013)

Composite spur gears were designed, fabricated and tested at NASA Glenn Research Center. The composite web was bonded only to the inner and outer hexagonal features that were machined from an initially all-metallic aerospace quality spur gear. The hybrid gear was tested against an all-steel gear and against a mating hybrid gear. Initial results indicate that this type of hybrid design may have a dramatic effect on drive system weight without sacrificing strength.

230 Area of Existence of Involute Gears (January/February 2010)

This paper presents a unique approach and methodology to define the limits of selection for gear parameters. The area within those limits is called the “area of existence of involute gears” (Ref. 1). This paper presents the definition and construction of areas of existence of both external and internal gears. The isograms of the constant operating pressure angles, contact ratios and the maximum mesh efficiency (minimum sliding) isograms, as well as the interference isograms and other parameters are defined. An area of existence allows the location of gear pairs with certain characteristics. Its practical purpose is to define the gear pair parameters that satisfy specific performance requirements before detailed design and calculations. An area of existence of gears with asymmetric teeth is also considered.

231 Liebherr LFG Grinding Machine (May 2013)

This machine concept facilitates highly productive profile grinding for large workpieces. The range for external and internal gears comprises models for manufacturing workpieces up to 2,000 millimeters – for industrial gear units, wind power, and marine propulsion applications

232 Optimal Modifications of Gear Tooth Surfaces (March/April 2011)

In this paper a new method for the introduction of optimal modifications into gear tooth surfaces - based on the optimal corrections of the profile and diameter of the head cutter, and optimal variation of machine tool settings for pinion and gear finishing—is presented. The goal of these tooth modifications is the achievement of a more favorable load distribution and reduced transmission error. The method is applied to face milled and face hobbed hypoid gears.

233 Our Experts Discuss Hobbing Ridges, Crooked Gear Teeth, and Crown Shaving (March/April 1992)

Question: When cutting worm gears with multiple lead stock hobs we find the surface is "ridged". What can be done to eliminate this appearance or is to unavoidable?

234 Gear Finishing with a Nylon Lap (September/October 2005)

The objective of this research is to develop a new lapping process that can efficiently make tooth flanks of hardened steel gears smooth as a mirror.

235 Girth Gear Inspection - Pre- and Post-Manufacture (August 2013)

What are the ins-and-outs of quality inspection of girth gears, from both a manufacturer and buyer perspective? Our experts respond.

236 Suitability of High Density Powder Metal Gears for Gear Applications (January/February 2001)

The implementation of powder metal (PM)components in automotive applications increases continuously, in particular for more highly loaded gear components like synchromesh mechanisms. Porosity and frequently inadequate material properties of PM materials currently rule out PM for automobile gears that are subject to high loads. By increasing the density of the sintered gears, the mechanical properties are improved. New and optimized materials designed to allow the production of high-density PM gears by single sintering may change the situation in the future.

237 Bevel Gear Cutting Methods (June 2016)

THE FINAL CHAPTER This is the last in the series of chapters excerpted from Dr. Hermann J. Stadtfeld’s Gleason Bevel Gear Technology — a book written for specialists in planning, engineering, gear design and manufacturing. The work also addresses the technical information needs of researchers, scientists and students who deal with the theory and practice of bevel gears and other angular gear systems. While all of the above groups are of course of invaluable importance to the gear industry, it is surely the students who hold the key to its future. And with that knowledge it is reassuring to hear from Dr. Stadtfeld of the enthusiastic response he has received from younger readers of these chapter installments.

238 Surface Characteristics of Hobbed Gears (July 2017)

Gear hobbing is one of the most productive manufacturing processes for cylindrical gears. The quality of the gears is a result of the tool quality, the precision of the workpiece, tool clamping and kinematics of the machine. The dry gear hobbing process allows machining of gears with a quality according to the DIN standard up to IT 5. To evaluate which gear quality is possible to machine with a given clamping and hob, it is useful to simulate the process in advance.

239 Reverse Engineering of Pure Involute Cylindrical Gears Using Conventional Measurement Tools (January/February 2000)

Designing a gear set implies a considerable effort in the determination of the geometry that fulfills the requirements of load capacity, reliability, durability, size, etc. When the objective is to design a new set of gears, there are many alternatives for the design, and the designer has the freedom to choose among them. Reverse engineering implies an even bigger challenge to the designer, because the problem involves already manufactured gears whose geometry is generally unknown. In this case, the designer needs to know the exact geometry of the actual gears in order to have a reference for the design.

240 Analysis of Load Distribution in Planet Gear Bearings (September 2011)

In epicyclic gear sets designed for aeronautical applications, planet gears are generally supported by spherical roller bearings with the bearing outer race integral to the gear hub. This article presents a new method to compute roller load distribution in such bearings where the outer ring can’t be considered rigid.

241 Deciding When to Go Plastic (July 2014)

Can my metal gear(s) be replaced with plastic gears?

242 Do No Destructive Testing (January/February 2013)

An overview of nondestructive testing and its importance in the manufacture of big gears.

243 Measurement of Involute Master (January/February 2013)

Our experts tackle the topic of measuring involute masters, including both master gears and gear inspection artifacts.

244 Light-Weight Design for Planetary Gear Transmissions (September 2013)

There is a great need for future powertrains in automotive and industrial applications to improve upon their efficiency and power density while reducing their dynamic vibration and noise initiation. It is accepted that planetary gear transmissions have several advantages in comparison to conventional transmissions, such as a high power density due to the power division using several planet gears. This paper presents planetary gear transmissions, optimized in terms of efficiency, weight and volume.

245 CNC Bevel Gear Generators and Flared Cup Gear Grinding (July/August 1993)

New freedom of motion available with CNC generators make possible improving tooth contact on bevel and hypoid gears. Mechanical machines by their nature are inflexible and require a special mechanism for every desired motion. These mechanisms are generally exotic and expensive. As a result, it was not until the introduction of CNC generators that engineers started exploring motion possibilities and their effect on tooth contact.

246 CBN Gear Grinding - A Way to Higher Load Capacity (November/December 1993)

Because of the better thermal conductivity of CBN abrasives compared to that of conventional aluminum oxide wheels, CBN grinding process, which induces residual compressive stresses into the component, and possibly improves the subsequent stress behavior. This thesis is the subject of much discussion. In particular, recent Japanese publications claim great advantages for the process with regard to an increased component load capacity, but do not provide further details regarding the technology, test procedures or components investigated. This situation needs clarification, and for the this reason the effect of the CBN grinding material on the wear behavior and tooth face load capacity of continuously generated ground gears was further investigated.

247 Investigation of Gear Rattle Phenomena (September/October 1992)

The acceptance by discerning customers of passenger cars is dependent upon both the actual noise lever and the subjective noise character. The subjective noise character itself can contain, among other features, undesirable noise phenomena which become apparent at certain points in the vehicle operating range. One such critical phenomenon is gear rattle, which is mainly present under low speed, high load conditions. Due to changes in the angular velocity of the crankshaft, gear rattle under driving conditions occurs at the unloaded gears and splines.

248 A New Method of Designing Worm Gears (July/August 1989)

The first part of this article describes the analytical design method developed by the author to evaluate the load capacity of worm gears. The second part gives a short description of the experimental program and testing resources being used at CETIM to check the basic assumptions of the analytical method; and to determine on gears and test wheels the surface pressure endurance limits of materials that can be used for worm gears. The end of the article compares the results yielded by direct application of the method and test results.

249 CNC Gear Grinding Methods (May/June 1997)

Grinding in one form or another has been used for more than 50 years to correct distortions in gears caused by the high temperatures and quenching techniques associated with hardening. Grinding improves the lead, involute and spacing characteristics. This makes the gear capable of carrying the high loads and running at the high pitch line velocities required by today's most demanding applications. Gears that must meet or exceed the accuracy requirements specified by AGMA Quality 10-11 or DIN Class 6-7 must be ground or hard finished after hear treatment.

250 Helical Gear Mathematics Formulas and Examples (May/June 1988)

The following excerpt is from the Revised Manual of Gear Design, Section III, covering helical and spiral gears. This section on helical gear mathematics shows the detailed solutions to many general helical gearing problems. In each case, a definite example has been worked out to illustrate the solution. All equations are arranged in their most effective form for use on a computer or calculating machine.

251 Systematic Approach to Designing Plastic Spur and Helical Gears (November/December 1989)

Plastic gears are being used increasingly in applications, such as printers, cameras, small household appliances, small power tools, instruments, timers, counters and various other products. Because of the many variables involved, an engineer who designs gear trains on an occasional basis may find the design process to be somewhat overwhelming. This article outlines a systematic design approach for developing injection molded plastic spur and helical gears. The use of a computer program for designing plastic gears is introduced as an invaluable design tool for solving complex gearing equations.

252 The Road Leads Straight to Hypoflex (March/April 2010)

A new method for cutting straight bevel gears.

253 Fundamentals of Bevel Gear Hard Cutting (November/December 1990)

Some years back, most spiral bevel gear sets were produced as cut, case hardened, and lapped. The case hardening process most frequently used was and is case carburizing. Many large gears were flame hardened, nitrided, or through hardened (hardness around 300 BHN) using medium carbon alloy steels, such as 4140, to avoid higher distortions related to the carburizing and hardening process.

254 Efficient Methods for the Synthesis of Compound Planetary Differential Gear Trains for Multiple Speed Ratio Generation (July/August 1990)

This article presents an efficient and direct method for the synthesis of compound planetary differential gear trains for the generation of specified multiple speed ratios. It is a train-value method that utilizes the train values of the integrated train components of the systems to form design equations which are solved for the tooth numbers of the gears, the number of mating gear sets and the number of external contacts in the system. Application examples, including vehicle differential transmission units, rear-end differentials with unit and fractional speed ratios, multi-input functions generators and robot wrist joints are given.

255 Optimism in Wind Abounds (January/February 2009)

Big gears and wind turbines go together like bees and honey, peas and carrots, bread and butter and—well, you get the idea. Wind isn’t just big right now, it’s huge. The wind industry means tremendous things for the energy dependent world we live in and especially big things for gear manufacturers and other beleaguered American industries.

256 Helical Gear Mathematics, Formulas and Examples Part II (July/August 1988)

The following excerpt is from the Revised Manual of Gear Design, Section III, covering helical and spiral gears. This section on helical gear mathematics shows the detailed solutions to many general helical gearing problems. In each case, a definite example has been worked out to illustrate the solution. All equations are arranged in their most effective form for use on a computer or calculating machine.

257 Viewpoint (November/December 1988)

Eliot K. Buckingham explains the procedure for proper measurement over wires for worm gears, in response to last issue's article.

258 Fillet Geometry of Ground Gear Teeth (January/February 1989)

This article investigates fillet features consequent to tooth grinding by generating methods. Fillets resulting from tooth cutting and tooth grinding at different pressure angles and with different positions of grinding wheel are compared. Ways to improve the final fillet of the ground teeth with regard to tooth strength and noise, as well as the grinding conditions, are shown. "Undergrinding" is defined and special designs for noiseless gears are described.

259 Looming Large (January/February 2016)

Let’s talk about large gears. Not the size or scope or inspection process, but the forecast and market potential in areas that utilize these massive components. We’ll examine key industry segments like energy and mining and tap IHS Economics for a forecast for 2016 and 2017 (spoiler alert: it’s not great). Additionally, we’ll discuss some of the critical factors influencing global big gear manufacturers Ferry-Capitain and Hofmann Engineering.

260 Gear Terms You Didn't Know About (May/June 1996)

The word gear, in various forms, has been in use since around A.D. 1200, according to the Oxford English Dictionary. Last issue we brought you Shakespearean gears. Now we'd like to show you some of the uses Americans have given our favorite word (from the Random House Dictionary of American Slang).

261 Product News (January/February 2009)

The complete product news section from the January/February 2009 issue of Gear Technology, featuring giant-sized David Brown girth gears, gear inspection up to 4.5 meters and the latest Gleason gear grinder.

262 The Elementary Theory for the Synthesis of Constant Direction Pointing Chariots (or Rotation Neutralizers) (November/December 1988)

The south-pointing chariot exhibited at the Smithsonian Institution, Washington, D.C., (circa 2600 BC)is shown in Fig. 1. Although the mechanism is ancient, it is by no means either primitive or simplistic. The pin-tooth gears drive a complex system, wherein the monk on the top of the chariot continues to point in a preset direction, no matter what direction the vehicle in moved, without a slip of the wheels.(1)

263 Alternative Lubrication Methods for Large Open Gear Drives (September/October 1996)

The type of lubricant and the method of applying it to the tooth flanks of large open gears is very important from the point of view of lubrication technology and maintenance. When selecting the type of lubricant and the application method, it is important to check whether it is possible to feed the required lubricant quantity to the load-carrying tooth flanks, This is necessary to avoid deficient lubrication, damage to the gear and operational malfunctions. It is important to determine the type of lubricant, which may be fluid or grease-like. The consistency of the lubricant will have a direct impact on the ability of the lubrication system to feed adequately the lubricant to the gear. The interactions between the common types of lubricant and the lubrication application methods for open gear drives are shown in Fig. 1.

264 Hard Gear Finishing With CBN-Basic Considerations (May/June 1998)

For over 50 years, grinding has been an accepted method of choice for improving the quality of gears and other parts by correcting heat treat distortions. Gears with quality levels better than AGMA 10-11 or DIN 6-7 are hard finished, usually by grinding. Other applications for grinding include, but are not limited to, internal/external and spur/helical gear and spline forms, radius forms, threads and serrations, compressor rotors, gerotors, ball screw tracks, worms, linear ball tracks, rotary pistons, vane pump rotators, vane slots, and pump spindles.

265 At the PEEK of the Polymer Food Chain (June 2010)

In the hypercompetitive race to increase automobile efficiency, Metaldyne has been developing its balance shaft module line with Victrex PEEK polymer in place of metal gears. The collaborative product development resulted in significant reductions in inertia, weight and power consumption, as well as improvement in noise, vibration and harshness (NVH) performance.

266 The Natural (November/December 2013)

Gears in nature: The Issus develops working gears in response to selective pressure.

267 Guidelines for Modern Bevel Gear Grinding (August 2008)

This paper acknowledges the wide variety of manufacturing processes--especially in grinding--utlized in the production of bevel gears...

268 Hypoloid Gear with Small Shaft Angles and Zero-to-Large Offsets (November/December 2009)

Beveloid gears are used to accommodate a small shaft angle. The manufacturing technology used for beveloid gearing is a special setup of cylindrical gear cutting and grinding machines. A new development, the so-called Hypoloid gearing, addresses the desire of gear manufacturers for more freedoms. Hypoloid gear sets can realize shaft angles between zero and 20° and at the same time, allow a second shaft angle (or an offset) in space that provides the freedom to connect two points in space.

269 Plastic Gear Standards: A Balancing Act (March/April 2007)

Creating standards for plastic gears calls for a deft touch. The challenge is to set uniform guidelines, yet avoid limiting the creative solutions plastic offers gear designers.

270 High Speed Hobbing of Gears With Shifted Profiles (July/August 1988)

The newer profile-shifted (long and short addendum) gears are often used as small size reduction gears for automobiles or motorcycles. The authors have investigated the damage to each cutting edge when small size mass-produced gears with shifted profiles are used at high speeds.

271 Process Model for Honing Larger Gears (November/December 2015)

Hard finishing technology, e.g. — honing — is used to manufacture high-performance gears. Gear honing is primarily used to hard finish small- and medium-sized automotive gears. And yet trials have shown that gears with a module larger than mn = 4 mm can also be honed efficiently, but problems often occur due to unstable process design. In this paper a model to improve the process design is described.

272 A Bicycle with Real Gears (May/June 2003)

The Addendum team was in Chicago in early March, for the National Manufacturing Week show, when it saw something unusual: a bicycle with gears. Real gears, Spiral bevel gears, in fact.

273 Myths and Miracles of Gear Coating (July/August 1999)

Three years ago, coated gears seemed to be the perfect solution for the Micro Marine Corporation. The early designs for the gear drive of their MicroCAT human-powered boat used a combination of thin-film dry gear coatings with lubrication and wear-resistance properties. These coatings simplified their design, provided corrosion resistance, made the gear drive environmentally safe and eliminated the need for gear drive lubrication and maintenance. It was a success story in the making.

274 Analyzing Gear Tooth Stress as a Function of Tooth Contact Pattern Shape and Position (January/February 1985)

The development of a new gear strength computer program based upon the finite element method, provides a better way to calculate stresses in bevel and hypoid gear teeth. The program incorporates tooth surface geometry and axle deflection data to establish a direct relationship between fillet bending stress, subsurface shear stress, and applied gear torque. Using existing software links to other gear analysis programs allows the gear engineer to evaluate the strength performance of existing and new gear designs as a function of tooth contact pattern shape, position and axle deflection characteristics. This approach provides a better understanding of how gears react under load to subtle changes in the appearance of the no load tooth contact pattern.

275 Plastic Gearing Continues Converting the Unconverted (March/April 2016)

Plastic gears are everywhere today — throughout your car, at the oceans’ lowest depths, in deep space. The question, when is a metal gear a candidate for plastic conversion, can be addressed in three words, i.e. — what’s the application?

276 Automotive Transmission Design Using Full Potential of Powder Metal (August 2013)

For metal replacement with powder metal (PM) of an automotive transmission, PM gear design differs from its wrought counterpart. Indeed, complete reverse-engineering and re-design is required so to better understand and document the performance parameters of solid-steel vs. PM gears. Presented here is a re-design (re-building a 6-speed manual transmission for an Opel Insignia 4-cylinder, turbocharged 2-liter engine delivering 220 hp/320 N-m) showing that substituting a different microgeometry of the PM gear teeth -- coupled with lower Young’s modulus -- theoretically enhances performance when compared to the solid-steel design.

277 Alternative Gear Manufacturing (July/August 1998)

the gear industry is awash in manufacturing technologies that promise to eliminate waste by producing gears in near-net shape, cut production and labor costs and permit gear designers greater freedom in materials. These methods can be broken down into the following categories: alternative ways to cut, alternative ways to form and new, exotic alternatives. Some are new, some are old and some are simply amazing.

278 Case Depth and Load Capacity of Case-Carburized Gears (March/April 2002)

Compared to non-heat-treated components, case-carburized gears are characterized by a modified strength profile in the case-hardened layer. The design of case-carburized gears is based on defined allowable stress numbers. These allowable stress numbers are valid only for a defined "optimum" case depth. Adequate heat treatment and optimum case depth guarantee maximum strength of tooth flank and tooth root.

279 Design of High Contact Ratio Spur Gears Cut With Standard Tools (July/August 2003)

In high precision and heavily loaded spur gears, the effect of gear error is negligible, so the periodic variation of tooth stiffness is the principal cause of noise and vibration. High contact ration spur gears can be used to exclude or reduce the variation of tooth stiffness.

280 Pushing the Envelope with Plastic (June 2007)

We were delighted to see the plastic gear set pictured on the cover of your March/April issue. UFE played the lead role in its design and manufacture.

281 Building Gears, Building Communities (November/December 2016)

Outside of our industry, there’s a whole slew of hobbyists working with gears to make clocks, art pieces, watches and all manner of bizarrely shaped gears (you know, all the people that usually end up featured right here in our Addendum section).

282 Performance of Skiving Hobs in Finishing Induction Hardened and Carburized Gears (May/June 2003)

In order to increase the load carrying capacity of hardened gears, the distortion of gear teeth caused by quenching must be removed by precision cutting (skiving) and/or grinding. In the case of large gears with large modules, skiving by a carbide hob is more economical than grinding when the highest accuracy is not required.

283 Practical Gear Characteristics: Process Characteristics of the Most Popular Cutting Methods (March/April 2016)

The cutting process consists of either a roll only (only generating motion), a plunge only or a combination of plunging and rolling. The material removal and flank forming due to a pure generating motion is demonstrated in the simplified sketch in Figure 1 in four steps. In the start roll position (step 1), the cutter profile has not yet contacted the work. A rotation of the work around its axis (indicated by the rotation arrow) is coupled with a rotation of the cutter around the axis of the generating gear (indicated by the vertical arrow) and initiates a generating motion between the not-yet-existing tooth slot of the work and the cutter head (which symbolizes one tooth of the generating gear).

284 Characterizaton of Retained Austenite in Case Carburized Gears and Its Influence on Fatigue Performance (May/June 2003)

Carburized helical gears with high retained austenite were tested for surface contact fatigue. The retained austenite before test was 60% and was associated with low hardness near the case's surface. However, the tested gears showed good pitting resistance, with fatigue strength greater than 1,380 MPa.

285 NOME Is Where The Energy Is (May 2016)

According to the U.K.-based WITT Energy website (, “The WITT is the only device in the world that can capture energy from all movement and turn it into electricity. No other energy system can exploit the full spectrum of movement, enabling it to harvest power from water (sea, river or tidal), wind and human or animal motion.”

286 Load Distribution in Planetary Gears (May/June 2001)

Two-shaft planetary gear drives are power-branching transmissions, which lead the power from input to output shaft on several parallel ways. A part of the power is transferred loss-free as clutch power. That results in high efficiency and high power density. Those advantages can be used optimally only if an even distribution of load on the individual branches of power is ensured. Static over-constraint, manufacturing deviations and the internal dynamics of those transmission gears obstruct the load balance. With the help of complex simulation programs, it is possible today to predict the dynamic behavior of such gears. The results of those investigations consolidate the approximation equations for the calculation of the load factors...

287 CNC Technology and the System-Independent Manufacture of Spiral Bevel Gears (September/October 1992)

CNC technology offers new opportunities for the manufacture of bevel gears. While traditionally the purchase of a specific machine at the same time determined a particular production system, CNC technology permits the processing of bevel gears using a wide variety of methods. The ideological dispute between "tapered tooth or parallel depth tooth" and "single indexing or continuous indexing" no longer leads to an irreversible fundamental decision. The systems have instead become penetrable, and with existing CNC machines, it is possible to select this or that system according to factual considerations at a later date.

288 The Capacity of Superfinished Vehicle Components to Increase Fuel Economy, Part I (January/February 2009)

This paper will present data from both laboratory and field testing demonstrating that superfinished components exhibit lower friction, operating temperature, wear and/ or higher horsepower, all of which translate directly into increased fuel economy.

289 Better Gears & Splines With Metrology (July 2007)

What does it mean to make "better" gears? Better gears more closely resemble the intended design parameters.

290 Spiral Bevel and Hypoid Gear Cutting Technology Update (July 2007)

Spiral bevel and hypoid gear cutting has changed significantly over the years. The machines, tools, processes and coatings have steadily advanced.

291 Designing Very Strong Gear Teeth by Means of High Pressure Angles (June 2017)

The purpose of this paper is to present a method of designing and specifying gear teeth with much higher bending and surface contact strength (reduced bending and surface contact stresses). This paper will show calculation procedures, mathematical solutions and the theoretical background equations to do this.

292 Into-Mesh Lubrication of Spur Gears - Part 2 (July/August 1989)

In the lubrication and cooling of gear teeth a variety of oil jet lubrication schemes is sometimes used. A method commonly used is a low pressure, low velocity oil jet directed at the ingoing mesh of the gears, as was analyzed in Reference 1. Sometimes an oil jet is directed at the outgoing mesh at low pressures. It was shown in Reference 2 that the out-of-mesh lubrication method provides a minimal impingement depth and low cooling of the gears because of the short fling-off time and fling-off angle.(3) In References 4 and 5 it was shown that a radially directed oil jet near the out-of-mesh position with the right oil pressure was the method that provided the best impingement depth.

293 Ground and Hobbed Globoidal Worm Sets (June 2017)

A reader wants to know: Are profile ground and hobbed globoidal worm sets better than multi-axis CNC generated globoidal worm gear sets for reduction of noise and vibration?

294 Grinding Induced Changes in Residual Stresses of Carburized Gears (March/April 2009)

This paper presents the results of a study performed to measure the change in residual stress that results from the finish grinding of carburized gears. Residual stresses were measured in five gears using the x-ray diffraction equipment in the Large Specimen Residual Stress Facility at Oak Ridge National Laboratory.

295 New Developments in TCA and Loaded TCA (May 2007)

How the latest techniques and software enable faster spiral bevel and hypoid design and development.

296 Measurement of Directly Designed Gears with Symmetric and Asymmetric Teeth (January/February 2011)

In comparison with the traditional gear design approach based on preselected, typically standard generating rack parameters, the Direct Gear Design method provides certain advantages for custom high-performance gear drives that include: increased load capacity, efficiency and lifetime; reduced size, weight, noise, vibrations, cost, etc. However, manufacturing such directly designed gears requires not only custom tooling, but also customization of the gear measurement methodology. This paper presents definitions of main inspection dimensions and parameters for directly designed spur and helical, external and internal gears with symmetric and asymmetric teeth.

297 Honing of Gears (August 2014)

The honing of gears - by definition - facilitates ease of operation, low noise and smoother performance in a transmission. Honing also contributes to reduced friction in the powertrain. Both the intense cutting (roughing process) as well as the functionally fine- finishing of transmission gears can be performed in one setup, on one machine.

298 Base Pitch Tables (September/October 1992)

There is one dimension common to both members of a pair of properly mating spur gears - the base pitch (BP). This base pitch is equal to the circular pitch of the gear on the base circle (see Fig. 1). For a helical gear, the base pitch can be described in either the transverse or normal plane, and is called the transverse base pitch (TBP) or normal base pitch (NBP), respectively. For parallel axis helical gears, both the TBP and NBP must be the same on both mating gears. For skew axis helical gears, only the NBP must be common.

299 Gears in Vogue (June 2008)

As much as we live, breathe, and sleep gears, there aren't too many of us who actually wear gears.

300 Ten Myths About Gear Lubrication (May/June 1995)

Myth No. 1: Oil Is Oil. Using the wrong oil is a common cause of gear failure. Gears require lubricants blended specifically for the application. For example, slow-speed spur gears, high-speed helical gears, hypoid gears and worm gears all require different lubricants. Application parameters, such as operating speeds, transmitted loads, temperature extremes and contamination risks, must be considered when choosing an oil. Using the right oil can improve efficiency and extend gear life.

301 Gear Design Deconstructed (May 2017)

How difficult is it to design a gear? It depends upon whom you ask.

302 Vive la Differential (March/April 2017)

Your automobile's differential is easily one of its most important components. This becomes crystal clear to anyone that has ever had to pony up to replace one. The differential, that mathy-driven, mechanically complex system that keeps axles and pinions running smoothly was invented by a watchmaker - for a watch.

303 2007 Holiday Buyers Guide (November/December 2007)

We love gears. We love talking about gears, writing about gears and examining gears. If you’re reading this cover to cover, it’s a safe bet you feel the same way. We also love collecting information for Gear Technology’s holiday buyer's guide. Call us sentimental.

304 A Proposed Pre-Finish Cylindrical Gear Quality Standard (September/October 2016)

This proposed standard would not make any recommendations regarding the required quality for any application. The intent is to establish standard pre-finish quality classes for typical finishing operations, which only include the inspection elements that are important to properly evaluate pre-finish gear quality as it applies to the finishing operation. It would be the responsibility of the manufacturing/process engineer, quality engineer, or other responsible individual to establish the required pre-finish quality class for their application.

305 Updating Modern Production Processes (August 2016)

Gear Technology interviews Scott Yoders of Liebherr about the latest gear machining technologies of relevance to automotive manufacturers.

306 Evaluation of Carburized & Ground Face Gears (September/October 2000)

Designers are constantly searching for ways to reduce rotocraft drive system weight. Reduced weight can increase the payload, performance, or power density of current and future systems. One example of helicopter transmission weight reduction was initiated as part of the United States Army Advanced Rotocraft Transmission program. This example used a split-torque, face-gear configuration concept (Ref. 1). compared to a conventional design with spiral-bevel gears, the split-torque, face-gear design showed substantial weight savings benefits. Also, the use of face gears allows a wide-range of possible configurations with technical and economic benefits (Ref. 2).

307 Worm Gear Efficiency Estimation and Optimization (June 2016)

This paper outlines the comparison of efficiencies for worm gearboxes with a center distance ranging from 28 – 150 mm that have single reduction from 5 to 100:1. Efficiencies are calculated using several standards (AGMA, ISO, DIN, BS) or by methods defined in other bibliographic references. It also deals with the measurement of torque and temperature on a test rig — required for the calibration of an analytical model to predict worm gearbox efficiency and temperature. And finally, there are examples of experimental activity (wear and friction measurements on a blockon- ring tribometer and the measurements of dynamic viscosity) regarding the effort of improving the efficiency for worm gear drivers by adding nanoparticles of fullerene shape to standard PEG lubricant

308 Calculation of the Tooth Root Strength of Worm Wheel Teeth Based on Local Stresses (November/December 2016)

How local stresses obtained from FEA can be used to determine fatigue strength of worm wheel teeth.

309 Quality and Surface of Gears Manufactured by Free-Form Milling with Standard Tools (January/February 2015)

The recently available capability for the free-form milling of gears of various gear types and sizes — all within one manufacturing system — is becoming increasingly recognized as a flexible machining process for gears.

310 Power Skiving of Cylindrical Gears on Different Machine Platforms (January/February 2014)

It has long been known that the skiving process for machining internal gears is multiple times faster than shaping, and more flexible than broaching, due to skiving's continuous chip removal capability. However, skiving has always presented a challenge to machines and tools. With the relatively low dynamic stiffness in the gear trains of mechanical machines, as well as the fast wear of uncoated cutters, skiving of cylindrical gears never achieved acceptance in shaping or hobbing, until recently.

311 Gear Noise and the Making of Silent Gears (March/April 1990)

Our research group has been engaged in the study of gear noise for some nine years and has succeeded in cutting the noise from an average level to some 81-83 dB to 76-78 dB by both experimental and theoretical research. Experimental research centered on the investigation into the relation between the gear error and noise. Theoretical research centered on the geometry and kinematics of the meshing process of gears with geometric error. A phenomenon called "out-of-bound meshing of gears" was discovered and mathematically proven, and an in-depth analysis of the change-over process from the meshing of one pair of teeth to the next is followed, which leads to the conclusion we are using to solve the gear noise problem. The authors also suggest some optimized profiles to ensure silent transmission, and a new definition of profile error is suggested.

312 Influence of Lubrication on Pitting and Micropitting Resistance of Gears (March/April 1990)

Pitting and micropitting resistance of case-carburized gears depends on lubricants and lubrication conditions. Pitting is a form of fatigue damage. On this account a short time test was developed. The test procedure is described. The "pitting test" was developed as a short time test to examine the influence of lubricants on micropitting. Test results showing the influence of case-carburized gears on pitting and micropitting are presented.

313 Gleason Cutter Head Improves Tool Life and Productivity (November/December 2009)

The Pentac Plus is the latest generation of Gleason’s Pentac bevel gear cutting system. It is designed to allow much higher tool life and improved productivity, especially for cutters using multiple face blade geometry.

314 Synthesis of Spiral Bevel Gears (March/April 1991)

There are different types of spiral bevel gears, based on the methods of generation of gear-tooth surfaces. A few notable ones are the Gleason's gearing, the Klingelnberg's Palloid System, and the Klingelnberg's and Oerlikon's Cyclo Palliod System. The design of each type of spiral bevel gear depends on the method of generation used. It is based on specified and detailed directions which have been worked out by the mentioned companies. However, there are some general aspects, such as the concepts of pitch cones, generating gear, and conditions of force transmissions that are common for all types of spiral bevel gears.

315 Product News (June 2016)

News about the Latest Products

316 Boom or Bust - Are You in the Right Markets (June/July 2013)

Over the past few months we've talked with a lot of gear manufacturers. Many of them tell us business is strong, while others are struggling with reduced demand. The difference between them isn't so much in the quality of their manufacturing operations, but rather trends in the end markets they serve.

317 Bevel Gear Manufacturing Troubleshooting (March/April 1991)

The quality of gearing is a function of many factors ranging from design, manufacturing processes, machine capability, gear steel material, the machine operator, and the quality control methods employed. This article discusses many of the bevel gear manufacturing problems encountered by gear manufacturers and some of the troubleshooting techniques used.

318 Producing Profile and Lead Modifications in Threaded Wheel and Profile Grinding (January/February 2010)

Modern gearboxes are characterized by high torque load demands, low running noise and compact design. In order to fulfill these demands, profile and lead modifications are being applied more often than in the past. This paper will focus on how to produce profile and lead modifications by using the two most common grinding processes—threaded wheel and profile grinding. In addition, more difficult modifications—such as defined flank twist or topological flank corrections—will also be described in this paper.

319 Pineapples, Corncobs & Other Hobbing Matters (July/August 1991)

Two questions on hobbing cover the various types of hobs and their unusual names, as well as the importance of hob swivel angle.

320 Gear Inspection Chart Evaluation; Specifying Unusual Worm Gear Sets (November/December 1991)

Question: When evaluating charts from a gear inspection machine, it is sometimes found that the full length of the profile traces vary, and that sometimes they are less than the length of active profile (above start of active profile-SAP) by up to 20%. This condition could be caused by a concentricity error between tooth grinding and shaping, or by unequal stock removal when grinding. (See Fig. 1.) Is it possible that some of the variation is coming from the inspection machine? How can variation from the inspection machine be reduced?

321 Hard Finishing By Conventional Generating and Form Grinding (March/April 1991)

The quality of a gear and its performance is determined by the following five parameters, which should be specified for each gear: Pitch diameter, involute form, lead accuracy, spacing accuracy, and true axis of rotation. The first four parameters can be measured or charted and have to be within tolerance with respect to the fifth. Pitch diameter, involute, lead, and spacing of a gear can have master gear quality when measured or charted on a testing machine, but the gear might perform badly if the true axis of rotation after installation is no longer the same one used when testing the gear.

322 Influence of CBN Grinding on Quality and Endurance of Drive Train Components (January/February 1991)

The merits of CBN physical characteristics over conventional aluminum oxide abrasives in grinding performance are reviewed. Improved surface integrity and consistency in drive train products can be achieved by the high removal rate of the CBN grinding process. The influence of CBN wheel surface conditioning procedure on grinding performance is also discussed.

323 The Geometric Design of Internal Gear Pairs (May/June 1990)

The paper describes a procedure for the design of internal gear pairs, which is a generalized form of the long and short addendum system. The procedure includes checks for interference, tip interference, undercutting, tip interference during cutting, and rubbing during cutting.

324 Limitations of Worm and Worm Gear Surfaces in Order to Avoid Undercutting (November/December 1990)

The dimensions of the worm and worm gear tooth surfaces and some of the worm gear drive parameters must be limited in order to avoid gear undercutting and the appearance of the envelope of lines of contact on the worm surface. The author proposes a method for the solution of this problem. The relations between the developed concept and Wildhaber's concept of the limit contact normal are investigated. The results of computations are illustrated with computer graphics.

325 Precision Gearing Lightens the Load for Off-Highway Equipment (June 2015)

Faith — paraphrasing the gospels of Matthew and Mark — can move mountains. But it helps if you have precision geared equipment.

326 A Clockwork Gear (January/February 1992)

Question: Could you explain what is meant by "horological gearing"? I never heard of this before, although I understand it has something to do with watches. Could you also explain the meaning of a "going gear train"?

327 An Emphasis on Accuracy (June/July 2011)

Meeting the many challenges of large gear inspection.

328 Determining Power Losses in the Helical Gear Mesh (September/October 2005)

This article reviews mathematical models for individual components associated with power losses, such as windage, churning, sliding and rolling friction losses.

329 New Approaches in Roll Testing Technology of Spiral Bevel and Hypoid Gear Sets (May/June 2005)

This paper presents a new approach in roll testing technology of spiral bevel and hypoid gear sets on a CNC roll tester applying analytical tools, such as vibration noise and single-flank testing technology.

330 A Novel Concept for High Accuracy Gear Calibration (May/June 2005)

The German National Metrology Institute has developed a novel calibration concept that allows for highly accurate calibration of product-like artifacts.

331 What to Know About Bevel Gear Grinding (September/October 2005)

Guidelines are insurance against mistakes in the often detailed work of gear manufacturing. Gear engineers, after all, can't know all the steps for all the processes used in their factories.

332 A Split Happened on the Way to Reliable, Higher-Volume Gear Grinding (September/October 2005)

Bevel gear manufacturers live in one of two camps: the face hobbing/lapping camp, and the face milling/grinding camp.

333 GPSys Critical to Spiral Bevel Gear Life (September/October 2008)

Impact Technologies considers commercial version of software package.

334 Injection Molded Innovation (June 2008)

Alternative business strategies from some alternative gear manufacturers.

335 INFAC Reports on Recent Hobbing and Heat Treating Experiments (July/August 1995)

Chicago- Results of recent studies on residual stress in gear hobbing, hobbing without lubricants and heat treating were reported by representatives of INFAC (Instrumented Factory for Gears) at an industry briefing in March of this year.

336 Letters to the Editor (June/July 2012)

A response to last issue's "Ask the Expert" feature on efficiency of hypoid gearing.

337 Tool Life and Productivity Improvement Through Cutting Parameter Setting and Tool Design in Dry High-Speed Bevel Gear Tooth Cutting (May/June 2006)

This article presents some of the findings of cutting investigations at WZL in which the correlation of cutting parameters, cutting materials, tool geometry and tool life have been determined.

338 New Checker Scan-Measures Stick Blades with Ruby-Tipped Probes (May/June 2006)

This month, German automakers will receive the first three units of Klingelnberg's new automated blade checker designed for the shop floor.

339 Writing the Standards (January/February 2011)

Gary A. Bish, director of product design technology for Horsburgh & Scott, discusses his role as chairman of the AGMA mill gearing committee.

340 Asymmetric Teeth: Bending Stress Calculation (March/April 2007)

This article includes a brief summary of the characteristics of involute asymmetric teeth and the problems connected with the related bending tests.

341 Cone Drive Double Enveloping Worm Gearing Design and Manufacturing (October/November 1984)

Worm gearing is of great antiquity, going back about 2100 years to Archimedes, who is generally acknowledged as its inventor. Archimedes' concept used an Archimedial spiral to rotate a toothed wheel. Development of the worm gearing principle progressed along conventional lines until about 500 years ago when Leonardo DaVinci evolved the double enveloping gear concept.

342 The Plastic Gear Pay-Off (March/April 2012)

Eliminating noise, weight and wear proves valuable in 2012.

343 Shorter Cycle Times for Carburizing (March/April 2006)

Dana Corp. is developing a process that carburizes a straight bevel gear to a carbon content of 0.8% in 60 fewer minutes than atmosphere carburizing did with an identical straight bevel.

344 Grinding, Finishing and Software Upgrades Abound (March/April 2011)

Machine tool companies are expanding capabilities to better accommodate the changing face of manufacturing. Customers want smaller-sized equipment to take up less valuable floor space, multifunctional machines that can handle a variety of operations and easy set-up changes that offer simplified operation and maintenance.

345 Reliable and Efficient Skiving (September 2011)

Klingelnberg's new tool and machine concept allow for precise production.

346 Engineering Constants (September/October 1986)

Rules and Formula for Gear Sizes

347 Kinematic Analysis of Robotic Bevel-Gear Trains (November/December 1986)

In robot configurations it is desirable to be able to obtain an arbitrary orientation of the output element or end-effector. This implies a minimum of two independent rotations about two (generally perpendicular) intersecting axes. If, in addition, the out element performs a mechanical task such as in manufacturing or assembly (e.g., drilling, turning, boring, etc.) it may be necessary for the end-effector to rotate about its axis. If such a motion is to be realized with gearing, this necessitates a three-degree-of-freedom, three-dimensional gear train, which provides a mechanical drive of gyroscopic complexity; i.e., a drive with independently controlled inputs about three axes corresponding to azimuth, nutation, and spin.

348 Tribology Aspects in Angular Transmission Systems, Part 1 (August 2010)

"General Explanations on Theoretical Bevel Gear Analysis" is part 1 of an eight-part series from Gleason's Dr. Hermann Stadtfeld.

349 Contact Surface Topology of Worm Gear Teeth (March/April 1988)

Among the various types of gearing systems available to the gear application engineer is the versatile and unique worm and worm gear set. In the simpler form of a cylindrical worm meshing at 90 degree axis angle with an enveloping worm gear, it is widely used and has become a traditional form of gearing. (See Fig. 1) This is evidenced by the large number of gear shops specializing in or supplying such gear sets in unassembled form or as complete gear boxes. Special designs as well as standardized ratio sets covering wide ratio ranges and center distanced are available with many as stock catalog products.

350 The Effect of Lubricant Traction On Wormgear Efficiency (January/February 1985)

The effect of various lubricant factors on wormgear efficiency has been evaluated using a variety of gear types and conditions. In particular, the significant efficiency improvements afforded by certain types of synthetic lubricants have been investigated to determine the cause of these improvements. This paper describes broad wormgear testing, both in the laboratory and in service, and describes the extent to which efficiency can be affected by changes in the lubricant; the effects of viscosity, viscosity index improvers and, finally, synthetic lubricants are discussed. The work concludes that lubricant tractional properties can play a significant role in determining gear efficiency characteristics.

351 KHV Planetary Gearing - Part II (January/February 1988)

Consisting of only a ring gear b meshing with one or two planets a, a carrier H and an equal velocity mechanism V, a KHV gearing(Fig. 1) is compact in structure, small in size and capable of providing a large speed ratio. For a single stage, its speed ratio can reach up to 200, and its size is approximately 1/4 that of a conventional multi-stage gear box.

352 KHV Planetary Gearing (November/December 1987)

Traditionally, a worm or a multi-stage gear box has been used when a large speed ratio is required. However, such boxes will become obsolete as size and efficiency become increasingly important considerations for a modern transmission. The single-enveloped worm gear has a maximum speed ratio of only 40 to 60. Its efficiency is only 30 to 60 per cent. The necessity of using bronze for the worm gear and grinding nitoalloy steel for the worm drives up material and manufacturing costs.

353 The Effect of Straight-Sided Hob Teeth (November/December 2010)

It is well known that hobs with straight-sided teeth do not cut true involutes. In this paper, the difference between the straight side of a hob tooth and the axial profile of an involute worm is evaluated. It is shown that the difference increases as the diametral pitch increases, to the extent that for fine-pitch gearing, the difference is insignificant.

354 The Efficiency Experts (September/October 2010)

Bradley University and Winzeler Gear collaborate on the design and development of an urban light vehicle.

355 The New Freedoms: Bevel Blades (September/October 2007)

Today, because of reduced cost of coatings and quicker turnaround times, the idea of all-around coating on three-face-sharpened blades is again economically viable, allowing manufacturers greater freedoms in cutting blade parameters, including three-face-sharpened and even four-face-sharpened blades.

356 Gear Grinding 1995 (July/August 1995)

Gear grinding is one of the most expensive and least understood aspects of gear manufacturing. But with pressures for reduced noise, higher quality and greater efficiency, gear grinding appears to be on the rise.

357 Our Experts Discuss Electronic Gearboxes, Plus Backlash and What to Do about it (September/October 1994)

Question: In the January/February issue of your magazine, we came across the term "electronic gearbox." We have seen this term used elsewhere as well. We understand that this EGB eliminates the change gear in the transmission line, but not how exactly this is done. Could you explain in more detail?

358 High-Tech Risks and Rewards (June 2009)

Aerospace/Defense contracts offer unique challenges for gear manufacturers.

359 Aerospace Gearing Research - An Update (June 2009)

A look at several American organizations doing cutting edge gear-related research for aerospace applications.

360 Optimizing Plastic Gear Geometry: An Inroduction to Gear Optimization (May/June 2002)

There are numerous engineering evaluations required to design gear sets for optimum performance with regard to torque capacity, noise, size and cost. How much cost savings and added gear performance is available through optimization? Cost savings of 10% to 30% and 100% added capacity are not unusual. The contrast is more pronounced if the original design was prone to failure and not fit for function.

361 Hypoid Gears with Involute Teeth (May 2015)

This paper presents the geometric design of hypoid gears with involute gear teeth. An overview of face cutting techniques prevalent in hypoid gear fabrication is presented. Next, the specification of a planar involute rack is reviewed. This rack is used to define a variable diameter cutter based upon a system of cylindroidal coordinates; thus, a cursory presentation of cylindroidal coordinates is included. A mapping transforms the planar involute rack into a variable diameter cutter using the cylindroidal coordinates. Hypoid gears are based on the envelope of this cutter. A hypoid gear set is presented based on an automotive rear axle.

362 My Gear Is Bigger than Your Gear (March/April 2013)

Industry battles it out for World's Largest Gear title.

363 Profile Shift (August 2012)

Three experts tackle the question of profile shift in this issue's edition of "Ask the Expert."

364 Stock Distribution Optimization in Fixed Setting Hypoid Pinions (July/August 2001)

Face-milled hypoid pinions produced by the three-cut, Fixed Setting system - where roughing is done on one machine and finishing for the concave-OB and convex-IB tooth flanks is done on separate machines with different setups - are still in widespread use today.

365 Revolutions (September/October 1999)

Welcome to Revolutions, the column that brings you the latest, most up-to-date and easy-to-read information about the people and technology of the gear industry.

366 Eddy Current Examination of Gear Systems (May/June 1997)

Nondestructive examination (NDE) of ferrous and nonferrous materials has long proved an effective maintenance and anomaly characterization tool for many industries. Recent research has expanded its applicability to include the inspection of large, open gear drives. Difficulties inherent in other NDE methods make them time-consuming and labor-intensive. They also present the user with the environmental problem of the disposal of used oil. The eddy current method addresses these problems.

367 Tooth Modification and Spur Gear Tooth Strain (September/October 1996)

A major source of helicopter cabin noise (which has been measured at over 100 decibels sound pressure level) is the gear box. Reduction of this noise is a NASA and U.S. Army goal.

368 The Geometry of Helical Mesh (September/October 1997)

In 1961 I presented a paper, "Calculating Conjugate Helical Forms," at the semi-annual meeting of the American Gear Manufacturers Association (AGMA). Since that time, thousands of hobs, shaper cutters and other meshing parts have been designed on the basis of the equations presented in that paper. This article presents the math of that paper without the formality of its development and goes on to discuss its practical application.

369 Gear Tooth Scoring Design Considerations for Spur and Helical Gearing (May/June 1985)

High speed gearing, operating with low viscosity lubricants, is prone to a failure mode called scoring. In contrast to the classic failure modes, pitting and breakage, which generally take time to develop, scoring occurs early in the operation of a gear set and can be the limiting factor in the gear's power capability.

370 Vectors in Gear Design (July/August 1999)

Friction weighs heavily on loads that the supporting journals of gear trains must withstand. Not only does mesh friction, especially in worm gear drives, affect journal loading, but also the friction within the journal reflects back on the loads required of the mesh itself.

371 Influence of Gear Design on Gearbox Radiated Noise (January/February 1998)

A major source of helicopter cabin noise (which has been measured at over 100 decibels sound pressure level) is the gearbox. Reduction of this noise is a NASA and U.S. Army goal. A requirement for the Army/NASA Advanced Rotorcraft Transmission project was a 10 dB noise reduction compared to current designs.

372 Feedback - My Gear Is Bigger than Your Gear (May 2013)

Readers respond regarding the article from March/April 2013.

373 Gear Design Optimization for Low Contact Temperature of a High Speed, Non Lubricated Spur Gear Pair (May 2013)

A gear design optimization approach applied to reduce tooth contact temperature and noise excitation of a high-speed spur gear pair running without lubricant. Optimum gear design search was done using the Run Many Cases software program. Thirty-one of over 480,000 possible gear designs were considered, based on low contact temperature and low transmission error. The best gear design was selected considering its manufacturability.

374 PPD Wear Protection Treatment for Large Parts Opens New Horizons (March/April 2014)

Environmentally friendly, highly efficient and lasting a product's lifetime. With characteristics like this, Pulsed-Plasma Diffusion (PPD) technology from Oerlikon Balzers has established itself as an industry standard for the treatment of large automotive press tooling. Now the technology specialists are targeting new applications with this advanced process, offering an alternative to traditional hard-chrome processes.

375 Gear Ratio Epicyclic Drives Analysis (June 2014)

It has been documented that epicyclic gear stages provide high load capacity and compactness to gear drives. This paper will focus on analysis and design of epicyclic gear arrangements that provide extremely high gear ratios. Indeed, a special, two-stage planetary arrangement may utilize a gear ratio of over one hundred thousand to one. This paper presents an analysis of such uncommon gear drive arrangements and defines their major parameters, limitations, and gear ratio maximization approaches. It also demonstrates numerical examples, existing designs, and potential applications.

376 Technological Fundamentals of CBN Bevel Gear Finish Grinding (November/December 1985)

The bevel gear grinding process, with conventional wheels, has been limited to applications where the highest level of quality is required.

377 Industry Forum (November/December 1985)

One of the current research activities here at California State University at Fullerton is systematization of existing knowledge of design of planetary gear trains.

378 A Practical Approach for Modeling a Bevel Gear (March/April 2015)

The geometry of the bevel gear is quite complicated to describe mathematically, and much of the overall surface topology of the tooth flank is dependent on the machine settings and cutting method employed. AGMA 929-A06 — Calculation of Bevel Gear Top Land and Guidance on Cutter Edge Radius — lays out a practical approach for predicting the approximate top-land thicknesses at certain points of interest — regardless of the exact machine settings that will generate the tooth form. The points of interest that AGMA 929-A06 address consist of toe, mean, heel, and point of involute lengthwise curvature. The following method expands upon the concepts described in AGMA 929-A06 to allow the user to calculate not only the top-land thickness, but the more general case as well, i.e. — normal tooth thickness anywhere along the face and profile of the bevel gear tooth. This method does not rely on any additional machine settings; only basic geometry of the cutter, blank, and teeth are required to calculate fairly accurate tooth thicknesses. The tooth thicknesses are then transformed into a point cloud describing both the convex and concave flanks in a global, Cartesian coordinate system. These points can be utilized in any modern computer-aided design software package to assist in the generation of a 3D solid model; all pertinent tooth macrogeometry can be closely simulated using this technique. A case study will be presented evaluating the accuracy of the point cloud data compared to a physical part.

379 Fundamental Study of Detection of Plastic Gear Failure Signs (March/April 2015)

This paper proposes a new method — using neural oscillators — for filtering out background vibration noise in meshing plastic gear pairs in the detection of signs of gear failure. In this paper these unnecessary frequency components are eliminated with a feed-forward control system in which the neural oscillator’s synchronization property works. Each neural oscillator is designed to tune the natural frequency to a particular one of the components.

380 Practical Considerations for the Use of Double-Flank Testing for the Manufacturing Control of Gearing - Part I (January/February 2014)

Part I of this paper describes the theory behind double-flank composite inspection, detailing the apparatus used, the various measurements that can be achieved using it, the calculations involved and their interpretation. Part II, which will appear in the next issue, includes a discussion of the practical application of double-flank composite inspection, especially for large-volume operations. Part II covers statistical techniques that can be used in conjunction with double-flank composite inspection, as well as an in-depth analysis of gage R&R for this technique.

381 Planet Carrier Design (January/February 2014)

With all the advantages of building float into a planetary gear system, what advantages are there to using a carrier in the first place, rather than simply having your planets float in the system?

382 Letters to the Editor (September 2013)

Readers respond to our "Job Shop Lean" column and the "My Gear is Bigger than Your Gear" article.

383 Products of Padua (May/June 2006)

Some things take time, but a magazine ad more than 600 years in the making?

384 Minimal Tooth Number of Flexspline in Harmonic Gear Drive with External Wave Generator (October 2013)

Wave generators are located inside of flexsplines in most harmonic gear drive devices. Because the teeth on the wheel rim of the flexspline are distributed radially, there is a bigger stress concentration on the tooth root of the flexspline meshing with a circular spline, where a fatigue fracture is more likely to occur under the alternating force exerted by the wave generator. The authors' solution to this problem is to place the wave generator outside of the flexspline, which is a scheme named harmonic gear drive (HGD) with external wave generator (EWG).

385 Riding the Rails (November/December 2013)

Are trains still a growth industry prospect for manufacturers?

386 GT Extras (January/February 2014)

Video from C&B Machinery; Introducing the Gear Technology Blog, featuring technical editor Charles D. Schultz; plus an online-exclusive article on big gear inspection.

387 Noise Reduction in Plastic & Powder Metal Gear Sets (July/August 1996)

The data discussed in this article was taken from an upright vacuum cleaner. This was a prototype cleaner that was self-propelled by a geared transmission. It was the first time that the manufacturer had used a geared transmission in this application.

388 Definition and Inspection of Profile and Lead of a Worm Wheel (November/December 1999)

Traditionally, profile and lead inspections have been indispensable portions of a standard inspection of an involute gear. This also holds true for the worm of a worm gear drive (Ref. 1). But the inspection of the profile and the lead is rarely performed on a worm wheel. One of the main reasons is our inability to make good definitions of these two elements (profile and lead) for the worm wheel. Several researchers have proposed methods for profile and lead inspections of a worm wheel using CNC machines or regular involute and lead inspections of a worm wheel using CNC machines or regular involute measuring machines. Hu and Pennell measured a worm wheel's profile in an "involute" section and the lead on the "pitch" cylinder (Ref. 2). This method is applicable to a convolute helicoid worm drive with a crossing angle of 90 degrees because the wheel profile in one of the offset axial planes is rectilinear. This straight profile generates an involute on the generated worm wheel. Unfortunately, because of the hob oversize, the crossing angle between the hob and the worm wheel always deviates from 90 degrees by the swivel angle. Thus, this method can be implemented only approximately by ignoring the swivel angle. Another shortcoming of this method is that there is only one profile and one lead on each flank. If the scanned points deviated from this curve, it produced unreal profile deviation. Octrue discussed profile inspection using a profile checking machine (Ref. 3).

389 The Changing Industrial Landscape (March/April 2009)

Companies weigh in on green technology and sustainable efforts.

390 Industry Forum (May/June 1985)

This letter is in response to your article asking the readers where their interests lie. The division of Rockwell International where I work has engineering departments in Cicero.

391 A Huge Success (September/October 1995)

Sivyer Steel Corporation, Bettendorf, IA, an ISO-9002-certified casting specialist, is familiar with tackling tough jobs. The company has built an international reputation as a supplier of high-integrity castings, especially those which require engineering and/or full machining. Its not unusual for Sivyer's customers, especially those in the mining, recycling, power generation, valve and nuclear fields, to ask the foundry to produce a one-of-a-kind casting - often something revolutionary - but AnClyde Engineered Products' request was a special challenge, even for Sivyer.

392 A Planetary System that Increases Power Density (January/February 2005)

Turnkey Design Services is manufacturing a planetary gear system to increase power density.

393 Racing Circuits (May/June 1996)

Zero to 125 MPH in five seconds. Maximum speed of 211 MPH. Seven-second pit stops. Formula One racing is a high-adrenalin sport - one which demands peak performance from drivers and machines alike.

394 Failure Mechanisms in Plastic Gears (January/February 2002)

Plastics as gear materials represent an interesting development for gearing because they offer high strength-to-weight ratios, ease of manufacture and excellent tribological properties (Refs. 1-7). In particular, there is a sound prospect that plastic gears can be applied for power transmission of up to 10 kW (Ref. 6).

395 Mirror Finishing of Tooth Surfaces Using A Trial Gear Grinder With Cubic-Boron-Nitride Wheel (November/December 1986)

In conventional gear grinders, grinding wheels with Alundum grains and a hardness of about 2000 HV have been used for finishing steel gears with hardnesses up to about 1000HV. In this case, the accuracy of the gears ground is greatly affected by wear of the grinding wheel because the difference in hardness is comparatively small when the gears are fully hardened.

396 Backlash in Bevel and Hypoid Gears (July 2017)

What is the relationship between angular backlash or mean normal backlash change and the axial movement of the ring gear in bevel and hypoid gears?

397 Analysis and Optimization of Contact Ratio of Asymmetric Gears (March/April 2017)

This article presents an analysis of asymmetric tooth gears considering the effective contact ratio that is also affected by bending and contact tooth deflections. The goal is to find an optimal solution for high performance gear drives, which would combine high load capacity and efficiency, as well as low transmission error (which affects gear noise and vibration).

398 AGMA & MPIF Develop Standards, Information Sheet for Powder Metal Gears (September/October 1996)

AGMA and members of the Metal Powder Industries Federation (MPIF) are three years into a joint project to develop specifications and an information sheet on rating powder metal gears. According to committee vice chairman Glen A. Moore of Burgess-Norton Mfg. Co., the first phase of the project, the publication of AGMA Standard "6009-AXX, Specifications for Powder Metallurgy Gears," should be completed in late 1996 or early 1997.

399 EDM Specialty Gears (May/June 1996)

The capabilities and limitations of manufacturing gears by conventional means are well-known and thoroughly documented. In the search to enhance or otherwise improve the gear-making process, manufacturing methods have extended beyond chip-cutting - hobbing, broaching, shaping, shaving, grinding, etc. and their inherent limitations based on cutting selection and speed, feed rates, chip thickness per tooth, cutting pressure, cutter deflection, chatter, surface finish, material hardness, machine rigidity, tooling, setup and other items.

400 I Like Big Gears and I Cannot Lie! (July 2015)

Many years ago, when asked how the five-meter gear was checked, the quality manager responded, “When they’re that big, they’re never bad!” That may have been the attitude and practice in the past, but it no longer serves the manufacturer nor the customer. Requirements have been evolving steadily, requiring gears to perform better and last longer.

401 The Beginner's Guide to Powder Metal Gears (September/October 1995)

Increasingly gear designers and product engineers are capitalizing on the economic advantages of powder metallurgy (P/M) for new and existing gear applications. Powder metal gears are found in automobiles, outdoor power equipment transmissions and office machinery applications as well as power hand tools, appliances and medial components.

402 Measuring Backlash in Bevel and Hypoid Gears (June 2014)

In this installment of Ask the Expert, Dr. Stadtfeld describes the best methods for measuring backlash in bevel gears.

403 3-D Finite Element Analysis of Long-Fiber Reinforced Composite Spur Gears (March/April 2002)

This article describes a method and a computer program that were developed for 3-D finite element analysis of long-fiber reinforced composite spur gears, in which long fibers are arranged along tooth profiles. For such a structure, the gear is composed of two regions; namely the long fiber reinforced and the chopped-fiber reinforced regions.

404 Hard Cutting - A Competitive Process in High Quality Gear Production (May/June 1987)

The higher load carrying capacities, compact dimensions and longer life of hardened gears is an accepted fact in industry today. However, the costs involved in case hardening and subsequent finishing operations to achieve these advantages are considerable. For example, in order to achieve desired running properties on larger gears, it has been necessary to grind the tooth flanks. This costly operation can now be replaced, in many cases, by a new Hard Cutting (HC) process which permits the cutting of hardened gears while maintaining extremely low tooling costs.

405 Reader Dialogue: Functional Measurement of Gears; More Good Gear Books (September/October 1992)

From time to time, the editors of "Shop Floor" receive correspondence from readers relating to particular articles they have written for past issues. As one of the purposes of this column is to provide a forum for the exchange of ideas, we reproduce here two of these letters and their replies. The subject of the first is the functional measurement of gears. (See Gear Technology, Sept/Oct, 1991, p. 17) Robert E. Smith writes the reply.

406 A Basic Guide to Deburring and Chamfering Gears (July/August 1995)

In today's industrial marketplace, deburring and chamfering are no longer just a matter of cosmetics. The faster speeds at which transmissions run today demand that gear teeth mesh as smoothly and accurately as possible to prevent premature failure. The demand for quieter gears also requires tighter tolerances. New heat treating practices and other secondary gear operations have placed their own set of demands on manufacturers. Companies that can deburr or chamfer to these newer, more stringent specifications - and still keep costs in line - find themselves with a leg up on their competition.

407 Contact Analysis of Gears Using a Combined Finite Element and Surface Integral Method (July/August 1993)

The complete and accurate solution t the contact problem of three-dimensional gears has been, for the past several decades, one of the more sought after, albeit elusive goals in the engineering community. Even the arrival on the scene in the mid-seventies of finite element techniques failed to produce the solution to any but the most simple gear contact problems.

408 Increased Load Capacity of Worm Gears by Optimizing the Worm Wheel Bronze (May/June 2002)

The lifetime of worm gears is usually delimited by the bronze-cast worm wheels. The following presents some optimized cast bronzes, which lead to a doubling of wear resistance.

409 Chamfering and Deburring External Parallel Axis Gears (November/December 1996)

The chamfering and deburring operations on gear teeth have become more important as the automation of gear manufacturing lines in the automotive industry have steadily increased. Quieter gears require more accurate chamfers. This operation also translates into significant coast savings by avoiding costly rework operations. This article discusses the different types of chamfers on gear teeth and outlines manufacturing methods and guidelines to determine chamfer sizes and angles for the product and process engineer.

410 Gears With Ears (March/April 2001)

When you're manufacturing fun, very often you need gears. The Addendum team recently went on a behind-the-scenes gear-finding mission with Jerold S. Kaplan, Principal Engineer, Show/Ride Mechanical Engineering at Walt Disney Imagineering in Lake Buena Vista, FL. We found that at least part of Disney's magic comes from good, old-fashioned mechanical engineering.

411 The Calculation of Optimum Surface Carbon Content for Carburized Case Hardened Gears (March/April 2001)

For high-quality carburized, case hardened gears, close case carbon control is essential. While tight carbon control is possible, vies on what optimum carbon level to target can be wider than the tolerance.

412 A Brief History of Gears (July/August 1999)

No one is quite sure when gears were invented. It's universally agreed, however, that they've been transmitting motion in one form or another for quite a long time.

413 Robotic Automated Deburring of Aerospace Gears (January/February 2001)

This report presents some interim results from an ongoing project being performed by INFAC, the Instrumented Factory for Gears. The purposes of this initial phase of the project were to demonstrate the feasibility of robotic automated deburring of aerospace gears, and to develop a research agenda for future work in that area.

414 Things Are Heating Up in 2015 (March/April 2015)

In this special section, our editors have gathered recent news and information related to the heat treatment of gears. Here you’ll find a comprehensive assortment of news and upcoming events that will help you understand the various heat treatment processes available for gears and choose the best option for your projects, whether you heat treat in-house or send your gears to a commercial heat treating provider.

415 Influence of Coatings and Surface Improvements on the Lifetime of Gears (July/August 2004)

Surface coatings or finishing processes are the future technologies for improving the load carrying capacity of case hardened gears. With the help of basic tests, the influence of different coatings and finishing processes on efficiency and resistance to wear, scuffing, micropitting, and macropitting is examined.

416 Ferrography: A Noninvasive Method to Inspect Your Gears (July/August 2000)

Would you like to be able to see the condition of the gears in your transmissions without having to open the box and physically examine them? There is a way, and not too many people know about it. It's called Wear Particle Analysis, or ferrography, and it is just starting to get noticed.

417 The Submerged Induction Hardening of Gears (March/April 2001)

The tooth-by-tooth, submerged induction hardening process for gear tooth surface hardening has been successfully performed at David Brown for more than 30 years. That experience - backed up by in-depth research and development - has given David Brown engineers a much greater understanding of, and confidence in, the results obtainable from the process. Also, field experience and refinement of gear design and manufacturing procedures to accommodate the induction hardening process now ensure that gears so treated are of guaranteed quality.

418 Cool Gears (May/June 1999)

It's nice to have claim to fame. "We're probably the world's foremost authority on making gears out of ice," says Jeff Root of Virtual Engineering, Plymouth, MI.

419 The Kinematics of Conical Involute Gear Hobbing (July 2008)

Conical involute gears, also known as beveloid gears, are generalized involute gears that have the two flanks of the same tooth characterized by different base cylinder radii and different base helix angles.

420 Misalignment No Beauty in Gearsets (May/June 1991)

When we have problems with gearset failure, a common diagnosis is misalignment. What exactly is that and how do we prevent it? The second most common "killer" of good gear sets is misalignment (dirt, or abrasive wear, is first). Gear teeth simply won't carry the load if they don't touch, and the portion that does touch has to carry an overload to make up for the missing contact area.

421 Austempered Gears and Shafts: Tough Solutions (March/April 2001)

Austempered irons and steels offer the design engineer alternatives to conventional material/process combinations. Depending on the material and the application, austempering may provide the producers of gear and shafts with the following benefits: ease of manufacturing, increased bending and/or contact fatigue strength, better wear resistance or enhanced dampening characteristics resulting in lower noise. Austempered materials have been used to improve the performance of gears and shafts in many applications in a wide range of industries.

422 Ironclad Gears (July/August 1997)

This issue of Addendum is dedicated to gears that have served their country. There have been many, but among the most significant are surely those at work during the Civil War, when their application changed the nature of naval warfare forever. It's time to recall that role, namely, powering the revolving turret of the U.S.S. Monitor, one of the first "ironclad" vessels.

423 Evaluation of Bending Strength of Carburized Gears (May/June 2004)

The aim of our research is to clearly show the influence of defects on the bending fatigue strength of gear teeth. Carburized gears have many types of defects, such as non-martensitic layers, inclusions, tool marks, etc. It is well known that high strength gear teeth break from defects in their materials, so it’s important to know which defect limits the strength of a gear.

424 The Basics of Gear Theory, Part 2 (July 2015)

The first part of this publication series covered the general basics of involute gearing and applied the generating principle of cylindrical gears analogous to angular gear axis arrangements the kinematic coupling conditions between the two mating members have been postulated in three rules. Entering the world of bevel gears also required to dwell somewhat on the definition of conjugacy. The second part is devoted to the different generating gears and the chain of kinematic relationships between the gear - gear generator - pinion generator and pinion.

425 The Advantages of Ion Nitriding Gears (November/December 1996)

When it comes to setting the standard for gear making, the auto industry often sets the pace. Thus when automakers went to grinding after hardening to assure precision, so did the machine shops that specialize in gearing. But in custom manufacturing of gears in small piece counts, post-heat treat grinding can grind away profits too.

426 The Lubrication of Gears - Part II (May/June 1991)

What follows is Part 2 of a three-part article covering the principles of gear lubrication. Part 2 gives an equation for calculating the lubricant film thickness, which determines whether the gears operate in the boundary, elastohydrodynamic, or full-film lubrication regime. An equation for Blok's flash temperature, which is used for predicting the risk of scuffing, is also given.

427 Single Flank Testing of Gears (May/June 1984)

Presumably, everyone who would be interested in this subject is already somewhat familiar with testing of gears by traditional means. Three types of gear inspection are in common use: 1) measurement of gear elements and relationships, 2) tooth contact pattern checks and 3) rolling composite checks. Single Flank testing falls into this last category, as does the more familiar Double Flank test.

428 How Many Mice Does It Take to Design a Gear (January/February 1995)

Gear design has long been a "black art." The gear shop's modern alchemists often have to solve problems with a combination of knowledge, experience and luck. In many cases, trial and error are the only effective way to design gears. While years of experience have produced standard gearsets that work well for most situations, today's requirements for quieter, more accurate and more durable gears often force manufacturers to look for alternative designs.

429 Size and Material Influence on the Tooth Root, Pitting, Scuffing and Wear Load-Carrying Capacity of Fine-Module Gears (September 2011)

In this study, limiting values for the load-carrying-capacity of fine-module gears within the module range 0.3–1.0 mm were determined and evaluated by comprehensive, experimental investigations that employed technical, manufacturing and material influence parameters.

430 Endurance Limit for Contact Stress in Gears (October/November 1984)

With the publishing of various ISO draft standards relating to gear rating procedures, there has been much discussion in technical papers concerning the various load modification factors. One of the most basic of parameters affecting the rating of gears, namely the endurance limit for either contact or bending stress, has not, however, attracted a great deal of attention.

431 Scoring Load Capacity of Gears Lubricated with EP-Oils (October/November 1984)

The Integral Temperature Method for the evaluation of the scoring load capacity of gears is described. All necessary equations for the practical application are presented. The limit scoring temperature for any oil can be obtained from a gear scoring test.

432 Wear Resistance of Plasma and Pulse Plasma Nitrided Gears (March/April 2003)

In this study, wear behavior of plasma and pulse plasma nitrided gears, made from 42CrMo4 steel, was evaluated under a lubricated sliding and pitting regime.

433 Give Your Gears a Break - Select the Right Coupling! (May/June 1987)

How important is the right choice of coupling in determining successful machine design? Consider the following example. A transmission of appropriate size was needed to transfer the speed of the engine driver to that of the driven generator. The transmission was properly selected and sized to endure the rated power requirements indefinitely, but after only a short time in operation, it failed anyway. What happened? The culprit in the case was a coupling. It provided the necessary power and protection against misalignment but it lacked the ability to isolate the gears from the torque peaks of the diesel engine.

434 Gear Measuring Machine by NDG Method for Gears Ranging from Miniature to Super-Large (March/April 2011)

A new inspection method has several advantages over traditional methods, especially for very large or very small gears.

435 Development of Conical Involute Gears (Beveloids) for Vehicle Transmissions (November/December 2005)

Conical involute gears (beveloids) are used in transmissions with intersecting or skewed axes and for backlash-free transmissions with parallel axes.

436 Computerized Recycling of Used Gear Shaver Cutters (May/June 1993)

Most gear cutting shops have shelves full of expensive tooling used in the past for cutting gears which are no longer in production. It is anticipated that these cutters will be used again in the future. While this may take place if the cutters are "standard," and the gears to be cut are "standard," most of the design work done today involves high pressure angle gears for strength, or designs for high contact ratio to reduce noise. The re-use of a cutter under these conditions requires a tedious mathematical analysis, which is no problem if a computer with the right software is available. This article describes a computerized graphical display which provides a quick analysis of the potential for the re-use of shaving cutters stored in a computer file.

437 Induction Hardening of Gears and Critical Components - Part I (September/October 2008)

Induction hardening is a heat treating technique that can be used to selectively harden portions of a gear, such as the flanks, roots and tips of teeth, providing improved hardness, wear resistance, and contact fatigue strength without affecting the metallurgy of the core and other parts of the component that don’t require change. This article provides an overview of the process and special considerations for heat treating gears. Part I covers gear materials, desired microsctructure, coil design and tooth-by-tooth induction hardening.

438 Best Supporting Gears (August 2008)

No one seems to appreciate gears more than a Hollywood cinematographer.

439 Heat Treat Process and Material Selection for High Performance Gears (March/April 2003)

The selection of the heat treat process and the congruent material required for high performance gears can become very involved.

440 For the Love of Gears! (March/April 2008)

Digital sculptor extraordinaire Tom Longtin has always had an interest in gears.

441 Load Sharing Analysis of High-Contact-Ratio Spur Gears in Military Tracked Vehicle Applications (July 2010)

This paper deals with analysis of the load sharing percentage between teeth in mesh for different load conditions throughout the profile for both sun and planet gears of normal and HCR gearing—using finite element analysis. (FEA).

442 Large Gears, Better Inspection (July 2010)

Investment in Gleason GMM Series inspection equipment helps drive Milwaukee Gear's expansion into profitable new markets around the world—all hungry for high-precision custom gears and gear drives.

443 Manufacturing Net-Shaped, Cold-Formed Gears (May 2008)

A net-shaped metal forming process has been developed for manufacturing quality, durable, high-yield and cost-efficient gears for high-volume production.

444 An Approach to Pairing Bevel Gears from Conventional Cutting Machine with Gears Produced on 5-Axis Milling Machine (June 2015)

Developed here is a new method to automatically find the optimal topological modification from the predetermined measurement grid points for bevel gears. Employing this method enables the duplication of any flank form of a bevel gear given by the measurement points and the creation of a 3-D model for CAM machining in a very short time. This method not only allows the user to model existing flank forms into 3-D models, but also can be applied for various other purposes, such as compensating for hardening distortions and manufacturing deviations which are very important issues but not yet solved in the practical milling process.

445 Recent Inventions and Innovations in Induction Hardening of Gears and Gear-Like Components (March/April 2013)

This paper examines the expanding capabilities of induction hardening of gears through methods like spin hardening or tooth-by-tooth techniques.

446 Superfinishing Gears -- The State of the Art (November/December 2003)

Superfinishing the working surfaces of gears and their root fillet regions results in performance benefits.

447 Marking Time With Wood (March/April 2000)

Clocks with wooden gears? In these days of gears made from plastic, steel and exotic materials; it is a little unusual to hear about a practical application for wooden gears. But that is exactly what David Scholl, the owner of Changing Times, a Harlingen, TX, clockmaker is offering us.

448 Tooth Flank Fracture - Basic Principles and Calculation Model for a Sub-Surface-Initiated Fatigue Failure Mode of Case-Hardened Gears (August 2015)

Cracks initiated at the surface of case-hardened gears may lead to typical life-limiting fatigue failure modes such as pitting and tooth root breakage. Furthermore, the contact load on the flank surface induces stresses in greater material depth that may lead to crack initiation below the surface if the local material strength is exceeded. Over time the sub-surface crack propagation may lead to gear failure referred to as “tooth flank fracture” (also referred to as “tooth flank breakage”). This paper explains the mechanism of this subsurface fatigue failure mode and its decisive influence factors, and presents an overview of a newly developed calculation model.

449 High Power Transmission with Case-hardened Gears and Internal Power Branching (January/February 1985)

In the field of large power transmission gear units for heavy machine industry, the following two development trends have been highly influential: use of case hardened gears and a branching of the power flow through two or more ways.

450 Tooth-Bending Effects in Plastic Spur Gears (September/October 2007)

This paper describes the investigation of a steel-and-plastic gear transmission and presents a new hypothesis on the governing mechanism in the wear of plastic gears.

451 Experience with Large, High-Speed Load Gears (July 2007)

The main theme of this article is high-capacity, high-speed load gears in a power transmission range between 35 MW and 100 MW for generators and turbo-compressors driven by gas or steam turbines.

452 Issues of Gear Design Using 3D Solid Modeling Systems (January/February 1999)

More and more gear shops are wrestling with the issue of whether or not solid modeling is right for their gear design work. The Q & A Page of The Gear Industry Home Page has had numerous questions asking how to model gears in solid modeling applications such as AutoCAD, Solidworks and Pr/Engineer. Given the problems people have been having, we are presenting the step-by-step process for modeling gears in Pr/Engineer, but first we thought it would be a good idea to explore the question of whether or not you should even try to design gears using Pro/Engineer or any other 3D solid modeling program.

453 Predicted Effect of Dynamic Load on Pitting Fatigue Life for Low-Contact-Ratio Spur Gears (March/April 1989)

How dynamic load affects the pitting fatigue life of external spur gears was predicted by using NASA computer program TELSGE. TELSGE was modified to include an improved gear tooth stiffness model, a stiffness-dynamic load iteration scheme and a pitting-fatigue-life prediction analysis for a gear mesh. The analysis used the NASA gear life model developed by Coy, methods of probability and statistics and gear tooth dynamic loads to predict life. In general, gear life predictions based on dynamic loads differed significantly from those based on static loads, with the predictions being strongly influenced by the maximum dynamic load during contact.

454 Surface Roughness Measurements of Cylindrical Gears and Bevel Gears on Gear Inspection Machines (May 2015)

Alongside the macro test parameters on tooth flanks for profile and tooth traces, surface properties (roughness) play a decisive role in ensuring proper toothed gear function. This article addresses roughness measurement systems on tooth flanks. In addition to universal test equipment, modified test equipment based on the profile method for use on gears is addressed in particular. The equipment application here refers to cylindrical gear flanks and bevel gear flanks. The most important roughness parameters, as well as the implementation of the precise measurement procedure will also be described under consideration of the applicable DIN EN ISO standards as well as the current VDI/VDE Directive 2612 Sheet 5.

455 Into-Mesh Lubrication of Spur Gears - Part I (May/June 1989)

Several methods of oil jet lubrication of gears are practiced by the gear industry. These include the oil jet directed into the mesh, out of the mesh and radially directed into the gear teeth. In most cases an exact analysis is not used to determine the optimum condition such as, jet nozzle location, direction and oil jet velocity, for best cooling. As a result many gear sets are operating without optimum oil jet lubrication and cooling.

456 Solid Model Generation of Involute Cylindrical Gears (September/October 2003)

This paper presents approximate and accurate methods to generate solid models of involute cylindrical gears using Autodesk Inventor 3-D CAD software.

457 Proposal for Tip Relief Modification to Reduce Noise and Sensitivity to Meshing Conditions in Spur Gears (March/April 2006)

In this article, a new tip relief profile modification for spur gears is presented. The topography proposed here is a classical linear profile modification with a parabolic fillet.

458 Influences on Failure Modes and Load-Carrying Capacity of Grease-Lubricated Gears (January/February 2016)

In order to properly select a grease for a particular application, a sound knowledge of the influence of different grease components and operating conditions on the lubrication supply mechanism and on different failure modes is of great benefit.

459 Sourcing Gears and Gear-Related Products (August 2015)

Reshoring offers an opportunity for increased domestic gear production. Reshoring is growing at a steady pace in most industries, and is particularly strong in the gear intensive industries such as automotive, aerospace and construction equipment (Table 1). This article provides background on the overall trend and tools for the gear buyer and the gear producer to make the offshore vs. domestic decision.

460 Optimal Modifications on Helical Gears for Good Load Distribution and Minimal Wear (June 2015)

Helical gear teeth are affected by cratering wear — particularly in the regions of low oil film thicknesses, high flank pressures and high sliding speeds. The greatest wear occurs on the pinion — in the area of negative specific sliding. Here the tooth tip radius of the driven gear makes contact with the flank of the driving gear with maximum sliding speed and pressure.

461 Inclusion-Based Bending Strength Calculation of Gears (May 2017)

Reduced component weight and ever-increasing power density require a gear design on the border area of material capacity. In order to exploit the potential offered by modern construction materials, calculation methods for component strength must rely on a deeper understanding of fracture and material mechanics in contrast to empirical-analytical approaches.

462 Gear Fundamentals Reverse Engineering (July/August 1991)

Whether gear engineers have to replace an old gear which is worn out, find out what a gear's geometry is after heat treatment distortion, or just find out parameters of gears made by a competitor, sometimes they are challenged with a need to determine the geometry of unknown gears. Depending on the degree of accuracy required, a variety of techniques are available for determining the accuracy of an unknown gear. If a high degree of precision is important, a gear inspection device has to be used to verify the results. Frequently, several trial-and-error attempts are made before the results reach the degree of precision required.

463 New Book For Gear Purchaseres & Specifiers (May/June 1997)

This book is written for those among us, with or without a technical background, who have an occasional need to use, purchase or specify gears. The author assumes an audience that is not made up of experienced gear designers, but of people who do need to have a basic understanding of the criteria used by the designer. The subjects covered include not only the gears themselves, but their manufacturing methods, the systems that contain them and the terms used to describe them.

464 Selection of the Optimal Parameters of the Rack-Tool to Ensure the Maximum Gear Tooth Profile Accuracy (January/February 1999)

An analysis of possibilities for the selection of tool geometry parameters was made in order to reduce tooth profile errors during the grinding of gears by different methods. The selection of parameters was based on the analysis of he grid diagram of a gear and a rack. Some formulas and graphs are presented for the selection of the pressure angle, module and addendum of the rack-tool. The results from the grinding experimental gears confirm the theoretical analysis.

465 Gear Grinding With Dish Wheels (September/October 1999)

The grinding of gears with dish wheels (Maad type grinding machines) is widely viewed as the most precise method of gear grinding because of the very short and simple kinematic links between the gear and the tool, and also because the cutting edges of the wheels represent planar surfaces. However, in this grinding method, depending on the parameters of the gears and one of the adjustments (such as the number of teeth encompassed by the grinding wheels), so-called overtravel at the tip or at the root of the teeth being ground generally occurs. When this happens, machining with only one wheel takes place. As a result, the profile error and the length of the generating path increases while productivity decreases.

466 An American Success Story (March/April 1997)

Joe Garfien came to America in 1928 to play soccer. He also learned to cut gears and build a business. "When I came here [to America] I came in on a Friday, and I had to go work on Monday, so I found a job at Perfection Gear...and that's how I got started in gears."

467 Powder Metal Gear Design and Inspection (September/October 1996)

Powder metallurgy (P/M) is a precision metal forming technology for the manufacture of parts to net or near-net shape, and it is particularly well-suited to the production of gears. Spur, bevel and helical gears all may be made by made by powder metallurgy processing.

468 Carbide Rehobbing A New Technology That Works! (May/June 1994)

Many people in the gear industry have heard of skiving, a process wherein solid carbide or inserted carbide blade hobs with 15 - 60 degrees of negative rake are used to recut gears to 62 Rc. The topic of this article is the use of neutral (zero) rake solid carbide hobs to remove heat treat distortion, achieving accuracies of AGMA 8 to AGMA 14, DIN 10-5 and improving surface finish on gears from 8 DP - 96 DP (.3 module - .26 m.).

469 How to Carburize a Finished Gear (March/April 1995)

Precise heat treatment plays an essential role in the production of quality carburized gears. Seemingly minor changes in the heat treating process can have significant effects on the quality, expense and production time of a gear, as we will demonstrate using a case study from one of our customer's gears.

470 Heat Treating Challenges for the Future (March/April 1996)

The heat treating of gears presents a difficult challenge to both the heat treater and the gear manufacturer. The number and variety of variables involved in the manufacturing process itself and the subsequent heat treating cycle create a complex matrix of factors which need to be controlled in order to produce a quality product. A heat treater specializing in gears or a gear manufacturer doing his own heat treating must have a clear understanding of these issues in order to deliver a quality product and make a profit at the same time. The situation also presents a number of areas that could benefit greatly from continued research and development.

471 Gear Heat Treating by Induction (March/April 2000)

The induction hardening and tempering of gears and critical components is traditionally a hot subject in heat treating. In recent years, gear manufacturers have increased their knowledge in this technology for quality gears.

472 Properties of Tooth Surfaces due to Gear Honing with Electroplated Tools (November/December 2001)

In recent years, the demands for load capacity and fatigue life of gears constantly increased while weight and volume had to be reduced. To achieve those aims, most of today's gear wheels are heat treated so tooth surfaces will have high wear resistance. As a consequence of heat treatment, distortion unavoidably occurs. With the high geometrical accuracy and quality required for gears, a hard machining process is needed that generates favorable properties on the tooth surfaces and the near-surface material with high reliability.

473 Prediction of Surface Zone Changes in Generating Gear Grinding (March/April 2015)

One process for hard finishing gears is generating gear grinding. Due to its high process efficiency, generating gear grinding has replaced other grinding processes such as profile grinding in batch production of small- and middle-sized gears. Yet despite the wide industrial application of generating gear grinding, the process design is based on experience along with time- and cost-intensive trials. The science-based analysis of generating gear grinding demands a high amount of time and effort, and only a few published scientific analyses exist. In this report a thermo-mechanical process model that describes influences on the surface zone in generating gear grinding is introduced.

474 Chamfering and Deburring - the Underrated Process (August 2016)

Chamfering and deburring of cylindrical gears does not get much love from manufacturers. The process is seen as a necessary evil since it is adding cost without adding “value.” However, there are good reasons for not underrating this important auxiliary process. Chamfering and deburring takes care of several issues which may come up during the manufacture of quality gears.

475 Problem Solving for the Gear Industry (January/February 2017)

If you’ve got a gear performance problem, the Gear Research Institute (GRI) is here to help you. Since inception in 1982, GRI has been a primarily industry sponsored, experimentation driven research facility. Whether establishing the fatigue life of gears or evaluating the impact of manufacturing processes on the performance of gears, GRI has pioneered methods and procedures for characterizing such properties that are accepted by the aerospace, vehicle and other industry sectors.

476 Gear Research Institute (May 2013)

The essence of designing gears is often by necessity risk-averse, given that many of them are used in applications where loss of life is a distinct possibility. The Gear Research Institute (GRI) at The Pennsylvania State University conducts risk reduction testing with the same goal in mind - whether it be gears in fighter jets, Ferris wheels, tanks, or countless other gear-reliant vehicles and machinery.

477 Workholding Options (March/April 2013)

Question: We manufacture some gears that require an axial face as a datum, as well as locating on the bore for centering. Other gears use only the bore for both axial and radial locating. What type of workholding is appropriate for each type of part? Is there workholding that will work for both types?

478 A Gear with a Sweet Tooth (July/August 2002)

Gear manufacturers typically use plastic, steel or other metals to make their gears, but Andrew Shotts made his first gears out of sugar and chocolate.

479 Experimental Characterization of Bending Fatigue Strength in Gear Teeth (January/February 2003)

The effort described in this paper addresses a desire in the gear industry to increase power densities and reduce costs of geared transmissions. To achieve these objectives, new materials and manufacturing processes, utilized in the fabrication of gears, and being evaluated. In this effort, the first priority is to compare the performance of gears fabricated using current materials and processes. However, once that priority is satisfied, it rapidly transforms to requiring accurate design data to utilize these novel materials and processes. This paper describes the effort to address one aspect of this design data requirement.

480 Horsburgh & Scott: Heavy Duty Gear Expert (September/October 2003)

Big gears, They drive the machinery that rolls steel, grinds limestone, pulverizes coal, pumps mud, mixes rubber, raises bridges and does many other heavy-duty industrial jobs. For 117 years, big gears have also driven the business of Horsburgh & Scott of Cleveland, OH.

481 Using Hobs for Skiving; A Pre-Finish and Finishing Solution (May/June 1993)

Our company manufactures a range of hardened and ground gears. We are looking into using skiving as part of our finishing process on gears in the 4-12 module range made form 17 CrNiMO6 material and hardened to between 58 and 62 Rc. Can you tell us more about this process?

482 Line of Action: Concepts & Calculations (January/February 1993)

In the past gear manufacturers have had to rely on hob manufacturers' inspection of individual elements of a hob, such as lead, involute, spacing, and runout. These did not always guarantee correct gears, as contained elements may cause a hob to produce gears beyond tolerance limits.

483 The New Now: U.S. Workforce Sustainability (March/April 2012)

Faithful Addendum readers are accustomed to finding upbeat, whimsical and oddball stories about gears in this space. What follows is not about gears, exactly. Rather, it is, as opposed to the usual bleak news about America losing its manufacturing mojo—a look at a positive, hopeful development in that regard.

484 Gear Generating Using Rack Cutters (October/November 1984)

Universal machines capable of cutting both spur and helical gears were developed in 1910, followed later by machines capable of cutting double helical gears with continuous teeth. Following the initial success, the machines were further developed both in England and France under the name Sunderland, and later in Switzerland under the name Maag.

485 Curvic Coupling Design (November/December 1986)

Curvic Couplings were first introduced in 1942 to meet the need for permanent couplings and releasing couplings (clutches), requiring extreme accuracy and maximum load carrying capacity, together with a fast rate of production. The development of the Curvic Coupling stems directly from the manufacture of Zerol and spiral bevel gears since it is made on basically similar machines and also uses similar production methods. The Curvic Coupling can therefore lay claim to the same production advantages and high precision associated with bevel gears.

486 Investigation of the Noise and Vibration of Planetary Gear Drives (January/February 2006)

With the aim of reducing the operating noise and vibration of planetary gear sets used in automatic transmissions, a meshing phase difference was applied to the planet gears that mesh with the sun and ring gears.

487 The Effect of Flexible Components on the Durability, Whine, Rattle and Efficiency of an Automotive Transaxle Geartrain System (November/December 2009)

Gear engineers have long recognized the importance of considering system factors when analyzing a single pair of gears in mesh. These factors include important considerations such as load sharing in multi-mesh geartrains and bearing clearances, in addition to the effects of flexible components such as housings, gear blanks, shafts and carriers for planetary geartrains. However, in recent years, transmission systems have become increasingly complex—with higher numbers of gears and components—while the quality requirements and expectations in terms of durability, gear whine, rattle and efficiency have increased accordingly.

488 Gear Grinding 2003 (November/December 2003)

The benefits of ground gears are well known. They create less noise, transmit more power and have longer lives than non-ground gears. But grinding has always been thought of as an expensive process, one that was necessary only for aerospace or other high-tech gear manufacturing.

489 Clogged Supply Chain Has Gear Manufacturers in Hurry Up and Wait Mode (November/December 2008)

Never have so few served so many. That, in essence, describes gear makers and the role they play in our world. Think of it—although the gear cutting industry represents much less than one percent of the global workforce—the gears it produces are what make things run in practically every industry and profession imaginable. From bulldozers to Rolexes, gears are an integral part of the mix.

490 Gear Corrosion During the Manufacturing Process (September/October 2009)

No matter how well gears are designed and manufactured, gear corrosion can occur that may easily result in catastrophic failure. Since corrosion is a sporadic and rare event and often difficult to observe in the root fillet region or in finely pitched gears with normal visual inspection, it may easily go undetected. This paper presents the results of an incident that occurred in a gear manufacturing facility several years ago that resulted in pitting corrosion and intergranular attack (IGA).

491 Influence of Geometrical Parameters on the Gear Scuffing Criterion - Part I (March/April 1987)

The load capacity rating of gears had its beginning in the 18th century at Leiden University when Prof. Pieter van Musschenbroek systematically tested the wooden teeth of windmill gears, applying the bending strength formula published by Galilei one century earlier. In the next centuries several scientists improved or extended the formula, and recently a Draft International Standard could be presented.

492 Selection of a Proper Ball Size to Check an Involute Spur or Helical Cear Tooth (September/October 1987)

A much-used method for checking the tooth thickness of an involute gear tooth is to measure the dimension over two balls placed in most nearly opposite spaces in the case of external gears, and the dimension between the balls in the case of internal gears. This measurement is then checked against a pre-calculated dimension to denote an acceptable part.

493 What Is Runout, And Why Should I Worry About It (January/February 1991)

Runout is a troublemaker! Good shop practice for the manufacture or inspection of gears requires the control of runout. Runout is a characteristic of gear quality that results in an effective center distance variation. As long as the runout doesn't cause loss of backlash, it won't hurt the function of the gear, which is to transmit smooth motion under load from one shaft to another. However, runout does result in accumulated pitch variation, and this causes non-uniform motion, which does affect the function of the gears. Runout is a radial phenomenon, while accumulated pitch variation is a tangential characteristic that causes transmission error. Gears function tangentially. It is also possible to have a gear with accumulated pitch variation, but little or no runout.

494 Our Experts Discuss... (March/April 1991)

Question: I have just become involved with the inspection of gears in a production operation and wonder why the procedure specifies that four involute checks must be made on each side of the tooth of the gear being produced, where one tooth is checked and charted in each quadrant of the gear. Why is this done? These particular gears are checked in the pre-shaved, finish-shaved, and the after-heat-treat condition, so a lot of profile checking must be done.

495 The Right and Wrong of Modern Hob Sharpening (January/February 1992)

Precision gears play a vital role in today's economy. Through their application, automobile transmissions are more compact and efficient, ships sail faster, and diesel locomotives haul more freight. Today great emphasis is being placed upon the reduction of noise in all gear applications and, to be quiet, gears must be accurate.

496 Viewpoint (November/December 1990)

Dear Editor: Your article on the ITC's Report to the President on the condition of the U.S. gear industry (Sept./Oct. issue) was most interesting. I am wondering if the total report neglected to mention that some of our inability to export gears is due to our reluctance to provide metric countries with the metric module-based gears that overseas customers demand.

497 Involute Splines (September/October 1990)

Engineering design requires many different types of gears and splines. Although these components are rather expensive, subject to direct wear, and difficult to replace, transmissions with gears and splines are required for two very simple reasons: 1) Motors have an unfavorable (disadvantageous) relation of torque to number of revolutions. 2)Power is usually required to be transmitted along a shaft.

498 The Relationship of Measured Gear Noise to Measured Gear Transmission Errors (January/February 1988)

Vehicle gear noise testing is a complex and often misunderstood subject. Gear noise is really a system problem.(1) most gearing used for power transmission is enclosed in a housing and, therefore, little or no audible sound is actually heard from the gear pair.(2) The vibrations created by the gears are amplified by resonances of structural elements. This amplification occurs when the speed of the gear set is such that the meshing frequency or a multiply of it is equal to a natural frequency of the system in which the gears are mounted.

499 Estimating Hobbing Times (July/August 1989)

Hobbing is a continuous gear generation process widely used in the industry for high or low volume production of external cylindrical gears. Depending on the tooth size, gears and splines are hobbed in a single pass or in a two-pass cycle consisting of a roughing cut followed by a finishing cut. State-of-the-art hobbing machines have the capability to vary cutting parameters between first and second cut so that a different formula is used to calculate cycle times for single-cut and double-cut hobbing.

500 Approximating an Involute Tooth Profile (September/October 1990)

On many occasions a reasonably approximate, but not exact, representation of an involute tooth profile is required. Applications include making drawings, especially at enlarged scale, and laser or EDM cutting of gears, molds, and dies used to produce gears. When numerical control (NC) techniques are to be used, a simple way to model an involute can make the NC programming task much easier.

501 Effects of Axle Deflection and Tooth Flank Modification on Hypoid Gear Stress Distribution and Contact Fatigue Life (August 2009)

As is well known in involute gearing, “perfect” involute gears never work perfectly in the real world. Flank modifications are often made to overcome the influences of errors coming from manufacturing and assembly processes as well as deflections of the system. The same discipline applies to hypoid gears.

502 New ANSI-AGMA Accuracy Standards for Gears (March/April 2004)

AGMA has started to replace its 2000-A88 standard for gear accuracy with a new series of documents based largely on ISO standards. The first of the replacement AGMA standards have been published with the remainder coming in about a year. After serving as a default accuracy specification for U.S. commerce in gear products for several decades, the material in AGMA 2000-A88 is now considered outdated and in need of comprehensive revision.

503 Good Gears Start With Good Blanks (November/December 1987)

The quality of the finished gear is influenced by the very first machining operations of the blank. Since the gear tooth geometry is generated on a continuously rotating blank in hobbing or shaping, it is important that the timed relationship between the cutter and workpiece is correct. If this relationship is disturbed by eccentricities of the blank to its operating centerline, the generated gear teeth will not be of the correct geometry. During the blanking operations, the gear's centerline and locating surfaces are established and must be maintained as the same through the following operations that generate the gear teeth.

504 Form Diameter of Gears (May/June 1989)

One of the most frequently neglected areas of gear design is the determination of "form diameter". Form diameter is that diameter which specifies the transition point between the usable involute profile and the fillet of the tooth. Defining this point is important to prevent interference with the tip of the mating gear teeth and to enable proper preshave machining when the gear is to be finished with a shaving operation.

505 White Etching Areas on Case-Hardened Gears (September/October 1989)

The phenomenon of white layers, which arises from high stress, can be observed under a microscope after the white layers have been treated with a weak nitric acid solution. Their occurrences in zones of high shear stress can provide qualitatively valuable indications of the size and direction of the stress, and they can point out possible starting points for flank damage. An investigation of this phenomenon is described.

506 Asymmetric Gears: Parameter Selection Approach (June/July 2012)

In many gear transmissions, a tooth load on one flank is significantly higher and is applied for longer periods of time than for the opposite one; an asymmetric tooth shape reflects this functional difference. This paper describes an approach that rationalizes the degree of asymmetry (or asymmetry factor K) selection to meet a variety of operating conditions and requirements for custom gear drives.

507 How Do You Say Gears in Italian (March/April 2015)

It was late November in Northern Italy, and everything was coming up vinegar oil and high-performance cars for Cory Sanderson and the 11 other members of his Yankee armada.

508 Evaluation of Methods for Calculating Effects of Tip Relief on Transmission Error, Noise and Stress in Loaded Spur Gears (January/February 2012)

The connection between transmission error, noise and vibration during operation has long been established. Calculation methods have been developed to describe the influence so that it is possible to evaluate the relative effect of applying a specific modification at the design stage. These calculations enable the designer to minimize the excitation from the gear pair engagement at a specific load. This paper explains the theory behind transmission error and the reasoning behind the method of applying the modifications through mapping surface profiles and determining load sharing.

509 Systematic Investigations on the Influence of Case Depth on the Pitting and Bending Strength of Case Carburized Gears (July/August 2005)

The gear designer needs to know how to determine an appropriate case depth for a gear application in order to guarantee the required load capacity.

510 Pitting Load Capacity of Helical Gears (May 2008)

Influences of Load Distribution and Tooth Flank Modifications as Considered in a New, DIN/ISO-Compatible Calculation Method

511 Implementing ISO 18653-Gears: Evaluation of Instruments for Measurement of Individual Gears (May 2010)

A trial test of the calibration procedures outlined in ISO 18653—Gears: Evaluation of Instruments for the Measurement of Individual Gears, shows that the results are reasonable, but a minor change to the uncertainty formula is recommended. Gear measuring machine calibration methods are reviewed. The benefits of using workpiece-like artifacts are discussed, and a procedure for implementing the standard in the workplace is presented. Problems with applying the standard to large gear measuring machines are considered and some recommendations offered.

512 Gears - Subculture Chic (January/February 2011)

Whether consumed by its romantic charm or simply a casual fan of its Victorian sensibilities, there’s a growing interest in all things steampunk lately. From books, television and films to music, art and design, the desire to ‘reclaim technology’ is getting closer and closer to mainstream pop culture. Wherever you find steampunk, you’ll undoubtedly find a gear or two not far behind.

513 The Lubrication of Gears - Part 1 (March/April 1991)

This is a three-part article explaining the principles of gear lubrication. It reviews current knowledge of the field of gear tribology and is intended for both gear designers and gear operators. Part 1 classifies gear tooth failures into five modes and explains the factors that a gear designer and operator must consider to avoid gear failures. It defines the nomenclature and gives a list of references for those interested in further research. It also contains an in-depth discussion of the gear tooth failure modes that are influenced by lubrication and gives methods for preventing gear tooth failures.

514 The Lubrication of Gears - Part III (July/August 1991)

This is the final part of a three-part series on the basics of gear lubrication. It covers selection of lubricant types and viscosities, the application of lubricants, and a case history

515 Avoiding Interference In Shaper-Cut Gears (January/February 1996)

In the process of developing gear trains, it occasionally occurs that the tip of one gear will drag in the fillet of the mating gear. The first reaction may be to assume that the outside diameter of the gear is too large. This article is intended to show that although the gear dimensions follow AGMA guidelines, if the gear is cut with a shaper, the cutting process may not provide sufficient relief in the fillet area and be the cause of the interference.

516 The Gears of Avon & Other Tragedies (March/April 1996)

As part of the Addendum Team's never-ending quest to improve the overall cultural tone of the gear industry, we bring you the following: April 23 is the 432nd birthday of William Shakespeare.

517 Wear Protection for Gears (March/April 1996)

Several trends in mechanical engineering are leading to greater surface stress on components and thus to unacceptable wear. These trends include greater stresses due to increased power densities; the need to maintain high precision of components throughout their service life; and the environmental imperative to reduce use of lubricants and additives.

518 18 Things You Should Know About SPC for Gears (November/December 1996)

Statistical Precess Control (SPC) and statistical methods in general are useful techniques for identifying and solving complex gear manufacturing consistency and performance problems. Complex problems are those that exist in spite of our best efforts and the application of state-of-the-art engineering knowledge.

519 Gears in Congress & Other Odd Places (July/August 1995)

Gear Technology's bimonthly aberration - gear trivia, humor, weirdness and oddments for the edification and amusement of our readers. Contributions are welcome.

520 Initial Design of Gears Using an Artificial Neural Net (May/June 1993)

Many CAD (Computer Aided Design) systems have been developed and implemented to produce a superior quality design and to increase the design productivity in the gear industry. In general, it is true that a major portion of design tasks can be performed by CAD systems currently available. However, they can only address the computational aspects of gear design that typically require decision-making as well. In most industrial gear design practices, the initial design is the critical task that significantly effects the final results. However, the decisions about estimating or changing gear size parameters must be made by a gear design expert.

521 Comparing Surface Failure Modes in Bearings and Gears: Appearances vs. Mechanisms (July/August 1992)

In the 1960's and early 1970's, considerable work was done to identify the various modes of damage that ended the lives of rolling element bearings. A simple summary of all the damage modes that could lead to failure is given in Table 1. In bearing applications that have insufficient or improper lubricant, or have contaminants (water, solid particles) or poor sealing, failure, such as excessive wear or vibration or corrosion, may occur, rather than contact fatigue. Usually other components in the overall system besides bearings also suffer. Over the years, builders of transmissions, axles, and gear boxes that comprise such systems have understood the need to improve the operating environment within such units, so that some system life improvements have taken place.

522 Tooth Contact Shift in Loaded Spiral Bevel Gears (November/December 1992)

An analytical method is presented to predict the shifts of the contact ellipses on spiral bevel gear teeth under load. The contact ellipse shift is the motion of the point to its location under load. The shifts are due to the elastic motions of the gear and pinion supporting shafts and bearings. The calculations include the elastic deflections of the gear shafts and the deflections of the four shaft bearings. The method assumes that the surface curvature of each tooth is constant near the unloaded pitch point. Results from these calculations will help designers reduce transmission weight without seriously reducing transmission performance.

523 Frozen Gears (March/April 1993)

Durability is the most important criterion used to define the quality of a gear. The freezing of metals has been acknowledged for almost thirty years as an effective method for increasing durability, or "wear life," and decreasing residual stress in tool steels. The recent field of deep cryogenics (below -300 degrees F) has brought us high temperature superconductors, the superconducting super collider, cryo-biology, and magnotehydrodynamic drive systems. It has also brought many additional durability benefits to metals.

524 Controlling Carburizing for Top Quality Gears (March/April 1993)

A carburized alloy steel gear has the greatest load-carrying capacity, but only if it is heat treated properly. For high quality carburizing, the case depth, case microstructure, and case hardness must be controlled carefully.

525 Superfinishing Gears - The State of the Art, Part II (July/August 2005)

In a previous article, the authors identified two misconceptions surrounding gear superfinishing. Here, they tackle three more.

526 Gears Are Amazing (May/June 2005)

Or, should we say, aMAZEing ??

527 Cutting Gears on a Machining Center (November/December 2009)

Depo provides all-in-one machining capabilities for the gear industry.

528 Gears at Play (November/December 2003)

e-Bay shopping, newspaper reading and excessive e-mailing aren’t a problem for most managers in the gear industry, but now there’s a new employee distraction headed their way.

529 Honk if You Love Gears (March/April 2009)

The Addendum Team announces plans for the Gear Vanity Plate Hall of Fame.

530 High Performance Gears Using Powder Metallurgy (PM) Technology (November/December 2004)

Powder metallurgy (P/M) techniques have proven successful in displacing many components within the automobile drive train, such as: connecting rods, carriers, main bearing caps, etc. The reason for P/M’s success is its ability to offer the design engineer the required mechanical properties with reduced component cost.

531 Candy Gears - Where Mesh Meets Marshmallow (August 2009)

On the production floor at Knechtel, food scientists, chemists and engineers take part in Willy Wonka-like experiments in search of the perfect piece of candy.

532 Single-Flank Testing of Gears (May/June 2004)

This article was originally published 20 years ago, in Gear Technology’s first issue. It describes a method of evaluating the smoothness, or lack of smoothness, of gear motion. This lack of smoothness of motion, known as “transmission error,” is responsible for excitation of gear noise and problems of gear accuracy and sometimes has a relationship to gear failure.

533 Gears: Kid-Tested, Museum-Approved (September/October 2009)

When children are asked what they want to be when they grow up, the answers are undoubtedly diverse. Some immediately respond with doctor, lawyer or firefighter while others take a more creative approach with answers like spy, princess or superhero. The Addendum Staff has yet to come across a youngster that seems committed to a career in gear manufacturing.

534 Calculation of Slow Speed Wear of Lubricated Gears (November/December 1985)

On gear drives running with pitch line velocities below 0.5 m/s so called slow speed wear is often observed. To solve some problems, extensive laboratory test work was started 10 years ago. A total of circ. 300,000 h running time on FZG back-to-back test rigs have been run in this speed range.

535 Greener Gears (July/August 2004)

Companies around the world are learning to embrace the environment, and the gear industry is no exception. This special section takes a look at how some gear manufacturers are doing their part to conserve resources, preserve and protect the environment, and give back to the land. What we’ve found is that adopting environmental measures is far more than just good corporate citizenship. For many gear industry companies, good environmental practices also turn out to be good for the bottom line.

536 Induction Hardening of Gears and Critical Components - Part II (November/December 2008)

Part I, which was published in the September/October 2008 issue, covered gear materials, desired microstructure, coil design and tooth-by-tooth induction hardening. Part II covers spin hardening and various heating concepts used with it.

537 Gears R Us (November/December 2004)

The kid who wants to be just like his gear-loving dad when he grows up will hit the jackpot this Christmas if Santa uses Gear Technology’s holiday buying guide.

538 High Speed Gears (September/October 2007)

Above all, a gear is not just a mechanical transmission, but is developed to a system fulfilling multiple demands, such as clutch integration, selectable output speeds, and controls of highest electronic standards. This paper shows the basics for high-speed gear design and a selection of numerous applications in detailed design and operational needs.

539 The Lubrication of DLC Coated Gears with Environmentally Adapted Ester-Based Oil (July/August 2006)

A main limiting factor in extending the use of hard coatings to machine component application is the lack of knowledge about how these inert coatings perform under lubricated conditions using today's lubricants.

540 Galleria Gears (November/December 2006)

For those of us in the gear industry, the concept of gear design is all about involutes, ratios and diameters. Alexander Kirberg has a different vision.

541 New Approach to Computerized Design of Spur and Helical Gears (January/February 2005)

Applying "Dynamic Block Contours" allows the designer to predict gear quality at the earliest stage of the design process.

542 Tooth Flank Corrections of Wide Face Width Helical Gears that Account for Shaft Deflections (January/February 2005)

This paper discusses the influence of tip relief, root relief, load modification, end relief and their combinations on gear stresses and transmission errors due to shaft deflections.

543 Wicked Gears (January/February 2006)

It's not often that thespians and engineers find common ground, but the hit musical Wicked could provide conversational tidbits for right- and left-brainers alike.

544 Finish Hobbing Crowned Helical Gears without Twist (January/February 2006)

New tool from LMT-Fette provides combination of operations.

545 Transmission Error and Noise Emission of Spur Gears (March/April 2007)

Transmission error (TE) is recognized as one of the most important causes of gear acoustic emissions...

546 Bowling for Gears (March/April 2007)

Here's what Dennis was thinking...

547 How Gears Provide the Gallop in Carousel Horses (January/February 2008)

As far back as the 12th century, men in Turkey and Arabia played a game referred to as carosello or garosello by Spanish and Italian crusaders.

548 Calculating Gears (January/February 1997)

Interesting gear factoids discovered wasting time on the Net while pretending to be working...The first four-function mechanical calculator was built by the mathematician Gottfried Leibniz in 1694. While not commercially available for nearly 200 years, the design was the basis of many such calculators until well into this century.

549 Finishing of Gears by Ausforming (November/December 1987)

Almost all machines or mechanical systems contain precision contact elements such as bearings, cams, rears, shafts, splines and rollers. These components have two important common requirements: first, they must possess sufficient mechanical properties, such as, high hardness, fatigue strength and wear resistance to maximize their performance and life; second, they must be finished to close dimensional tolerances to minimize noise, vibration and fatigue loading.

550 Design for Silence: New Concepts and Techniques for Industrial Gears (September/October 1999)

For a long time, relatively high noise levels have been generally accepted for industrial gear units in the 10-100 kW power range. However, due to changing environmental awareness - both in and around industrial sites - customers expectations have moved drastically towards low noise as a key differentiating factor.

551 Specifying Custom Gears (May/June 1999)

Gear design and specification are not one and the same. They are the first two steps in making a gear. The designer sits down and mathematically defines the gear tooth, working with the base pitch of the gear, the pressure angle he wants to employ, the number of teeth he wants, the lead, the tooth thickness, and the outside, form and root diameters. With these data, the designer can create a mathematical model of the gear. At this stage, he will also decide whether the gear will be made from existing cutting tools or whether new tools will be needed, what kind of materials he will use, and whether or not he will have the gear heat treated and finished.

552 Tooth Root Optimization of Powder Metal Gears - Reducing Stress from Bending and Transient Loads (June/July 2013)

This paper will provide examples of stress levels from conventional root design using a hob and stress levels using an optimized root design that is now possible with PM manufacturing. The paper will also investigate how PM can reduce stresses in the root from transient loads generated by abusive driving.

553 Undercover Gears (March/April 2002)

Top Secret Code Name: Ginger Mission: Design, prototype and test a transmission for a new device. The transmission must be compact and efficient. It should have almost no backlash, and it must be able to operate in both forward and reverse. Most importantly, the transmission must be quiet. In fact, it shouldn't sound like a transmission at all. It should blend in with the environment and sound like music or the wind. This mission, should you choose to accept it, is top secret. Not even your employees can know what you're working on...

554 Calculating Dynamic Loads, Sizing Worm Gears and Figuring Geometry Factors (May/June 2001)

Q&A is an interactive gear forum. Send us you gear design, manufacturing, inspection or other related questions, and we will pass them to our panel of experts.

555 Worm Gears - Ask the Expert (October 2013)

How does one determine the center of a worm and a worm wheel? Also, what are the differences between the common worm tooth forms?

556 Heat Treat Suppliers Focused on Gears (August 2013)

Heat treat suppliers look to the gear industry and the upcoming combined Gear Expo/Heat Treat 2013 for new business.

557 Predicted Scuffing Risk to Spur and Helical Gears in Commercial Vehicle Transmissions (November/December 2012)

AGMA925–A03 scuffing risk predictions for a series of spur and helical gear sets of transmissions used in commercial vehicles ranging from SAE Class 3 through Class 8.

558 Program for Involute Equation to Develop Spur Gears on Pro-E Software (May/June 2002)

In effect, this article continues a previous Gear Technology article, "Modeling Gears In Pro/Engineer," published in the January/February 1999 issue. The previous article discussed drawing involute gear teeth using a program built into the Pro/E software.

559 The Barkhausen Noise Inspection Method for Detecting Grinding Damage in Gears (November/December 2002)

When hardened steel components are ground, there is always the possibility of damage to the steel in the form of residual stress or microstructural changes. Methods for detecting this sort of damage have always had one or more drawbacks, such as cost, time, complexity, subjectivity, or the use of hazardous chemicals.

560 Gears of Rockwell Hardness (September/October 2002)

Nobody's sure what went on in Bolsa Chica, CA, when gear-shaped stones were used there 8,700 years ago, but a popular belief is that at least some activity revolved around manufacturing.

561 Fundamentals of Gears and Gear Manufacturing (March/April 2003)

Video Review for March/April 2003.

562 The Broaching of Gears (March/April 1997)

Broaching is a process in which a cutting tool passes over or through a part piece to produce a desired form. A broach removes part material with a series of teeth, each one removing a specified amount of stock.

563 To Climb A Mountain, A Railroad Needs Gears (July/August 2003)

Recently, the Addendum team has taken a keen interest in a Swiss mountain. being the Addendum team, we haven't been interested in this rocky, fissured mountain for it natural majesty.

564 Fatigue Aspects of Case Hardened Gears (March/April 1999)

The efficient and reliable transmission of mechanical power continues, as always, to be a central area of concern and study in mechanical engineering. The transmission of power involves the interaction of forces which are transmitted by specially developed components. These components must, in turn, withstand the complex and powerful stresses developed by the forces involved. Gear teeth transmit loads through a complex process of positive sliding, rolling and negative sliding of the contacting surfaces. This contact is responsible for both the development of bending stresses at the root of the gear teeth and the contact stresses a the contacting flanks.

565 LES GEARS LYONNAISE (September/October 2014)

Soon upon setting down in this beautiful, former (43 B.C.) Roman Colony that is now the City of Lyon, I was careening to my hotel, Mach I-plastered to the back seat of a sleek, shinyblack Mercedes taxi, when I realized I was staring at - zut alors? - cornfields!

566 Special Gears Help Hatch a Summer Movie (January/February 2001)

Chicken Run - the summer that used stop-motion clay figures - is about a group of chickens laying a plan to escape from their farm before they're turned into chicken pies. Distributed by Steven Spielberg's Dream Works, Chicken Run is also about a group of specially-made worms and wheels.

567 Measuring Residual Stress in Gears (March/April 2015)

I have heard that X-ray diffraction does not tell the whole story and that I should really run a fatigue test. I understand this may be the best way, but is there another method that gives a high degree of confidence in the residual stress measurement?

568 Microsecond Heat Treatment of Gears (March/April 2000)

The performance of metal surfaces can be dramatically enhanced by the thermal process of rapid surface melting and re-solidification (RMRS). When the surface of a metal part (for instance, a gear) is melted and re-solidified in less than one thousandth of a second, the resulting changes in the material can lead to: Increased wear and corrosion resistance, Improved surface finish and appearance, Enhanced surface uniformity and purity, and Sealing of surface cracks and pores.

569 Gears On Ice (January/February 2000)

Saginaw, Michigan, may be home to the only gear operation in the world that requires the use of a Zamboni machine. It may also be the only place in the world where teeth on the Gears are optional.

570 Fabrication of Directly Designed Gears with Symmetric and Asymmetric Teeth (November/December 2014)

When compared with the traditional gear design approach — based on pre-selected, typically standard generating rack parameters — the alternative Direct Gear Design method provides certain advantages for custom, high-performance gear drives.

571 Ferritic Nitrocarburizing Gears to Increase Wear Resistance and Reduce Distortion (March/April 2000)

Quality gear manufacturing depends on controlled tolerances and geometry. As a result, ferritic nitrocarburizing has become the heat treat process of choice for many gear manufacturers. The primary reasons for this are: 1. The process is performed at low temperatures, i.e. less than critical. 2. the quench methods increase fatigue strength by up to 125% without distorting. Ferritic nitrocarburizing is used in place of carburizing with conventional and induction hardening. 3. It establishes gradient base hardnesses, i.e. eliminates eggshell on TiN, TiAIN, CrC, etc. In addition, the process can also be applied to hobs, broaches, drills, and other cutting tools.

572 Design Formulas for Evaluating Contact Stress in Generalized Gear Pairs (May/June 2001)

A very important parameter when designing a gear pair is the maximum surface contact stress that exists between two gear teeth in mesh, as it affects surface fatigue (namely, pitting and wear) along with gear mesh losses. A lot of attention has been targeted to the determination of the maximum contact stress between gear teeth in mesh, resulting in many "different" formulas. Moreover, each of those formulas is applicable to a particular class of gears (e.g., hypoid, worm, spiroid, spiral bevel, or cylindrical - spur and helical). More recently, FEM (the finite element method) has been introduced to evaluate the contact stress between gear teeth. Presented below is a single methodology for evaluating the maximum contact stress that exists between gear teeth in mesh. The approach is independent of the gear tooth geometry (involute or cycloid) and valid for any gear type (i.e., hypoid, worm, spiroid, bevel and cylindrical).

573 Precision Finish Hobbing (July/August 2000)

Nowadays, finish hobbing (which means that there is no post-hobbing gear finishing operation) is capable of producing higher quality gears and is growing in popularity.

574 The Gear Lover's Guide to Detroit (September/October 1997)

When traveling about in search of gears and other adventures, wise explorers bring along as much important information as they can. In the interest of keeping our readers as well-informed as possible, we bring you the following collection of Important Facts About Motor City.

575 Puzzling Together A Gear Pioneer (September/October 2001)

The Dictionary of American Biography describes him as "one of the founders of the gear-cutting industry in the United State." He built the first hobbing machine for cutting spur gears. He founded the companies that are now Boston Gear and Philadelphia Gear Corp.

576 Water Powered Machinery (January/February 2001)

In one of my many visits to northern New York state, which included the St. Lawrence River (Thousand Islands Region) and the Adirondack Mountains, I visited Croghan, a village on the Beaver River, which is fed by the Stillwater Resevoir in the Adirondack Mountains. At the base of a dam within the village, I found the remnants of a water turbine and a bevel gear drive system. Having worked for The Gleason Works for many years, I was intrigued by the remains of the bevel gears, which appeared to have had wooden teeth at one time.

577 Basic Honing & Advanced Free-Form Honing (July/August 1997)

Rotary gear honing is a crossed-axis, fine, hard finishing process that uses pressure and abrasive honing tools to remove material along the tooth flanks in order to improve the surface finish (.1-.3 um or 4-12u"Ra), to remove nicks and burrs and to change or correct the tooth geometry. Ultimately, the end results are quieter, stronger and longer lasting gears.

578 John Q. Gear Meets Martha Stewart (May/June 1997)

When you need totally useless information about gears, you can turn with confidence to the pages of Addendum, where we scour the globe for the obscure, the unusual and the ridiculous (the latter being or forte.)

579 New Approaches to Nitriding (March/April 1997)

The process of nitriding has been used to case harden gears for years, but the science and technology of the process have not remained stagnant. New approaches have been developed which are definitely of interest to the gear designer. These include both new materials and new processing techniques.

580 What - A June Issue (June 2007)

Just like most of the gear industry, we're extremely busy here at Gear Technology. While many of you are working hard to produce more gears, we're doing the same with magazines.

581 Detroit in 97 - the Biggest Gear Expo Ever (July/August 1997)

"A Decade of Performance" is the theme of the American Gear Manufacturers Association Gear Expo 97, to be held October 19-22 at Detroit's Cobo Hall. Products and services related to every aspect of the gear manufacturing process, from turning and grinding the blanks to coating and inspection of the gears,will be represented at the show.

582 Special Machine Manufacturer Brings Gear Making In-House (September/October 1997)

When you have a multi-million-dollar transfer line sitting on the shop floor waiting for gears that might take up to two months to get, you have a costly bottleneck.

583 Systematic Investigations on the Influence of Viscosity Index Improvers on EHL Film Thickness (November/December 2001)

Mineral-oil-base lubricants show a significant decrease of kinematic viscosity with rising temperature, as exemplified in Figure 1 by lubricants for vehicle gears. An important attribute of lubricants is their viscosity index (VI), according to DIN/ISO 2909 (Ref. 4). Viscosity index is a calculated coefficient, which characterizes the change of viscosity of lubricants as a function of temperature. A high viscosity index represents a low variation of viscosity due to temperature and vice versa. A low viscosity-temperature-dependence is required for lubricants that are operated at significantly varying temperature conditions, such as vehicle engine and gear lubricants in summer and winter time. This way, the oils remain flowing and pumpable at low temperatures on the one hand; and on the other hand, sufficiently thick lubricant films can be formed at higher temperatures for a safe separation of the surfaces.

584 ...and visions of wormwheels danced in their heads (November/December 2001)

Does anyone know where we can find a gear-shaped fruitcake? It's the holiday season again, and the Addendum staff has many friends. We'd like to get each of them the perfect holiday gift, something the demonstrates thought, caring and good will. Of course, we're looking for gifts with meaning, and for us, that can only mean gears.

585 Reducing Production Costs in Cylindrical Gear Hobbing and Shaping (March/April 2000)

Increased productivity in roughing operations for gear cutting depends mainly on lower production costs in the hobbing process. In addition, certain gears can be manufactured by shaping, which also needs to be taken into account in the search for a more cost-effective form of production.

586 An Experimental Study on the Effect of Power Honing on Gear Surface Topography (January/February 1999)

Gear noise associated with tooth surface topography is a fundamental problem in many applications. Operations such as shaving, gear grinding and gear honing are usually used to finish the gear surface. Often, gears have to be treated by a combination of these operations, e.g. grinding and honing. This is because gear honing operations do not remove enough stock although they do create a surface lay favorable for quiet operation. See Fig. 1 for typical honing process characteristics. Gear grinding processes, on the other hand, do remove stock efficiently but create a noisy surface lay.

587 Technology Tidbits (January/February 2002)

New Technique for Forging Crowned Helical Gears Createch Co. Ltd., a forging die manufacturer from Shizuoka, Japan, has developed a net-shape cold-forging process for forming helical gears and splines with crowned teeth.

588 One Man's Junk Equals Fellow Gear Lover's Treasures (May 2007)

Tom Every has a collection of gears that would rival many small warehouses.

589 Beginning Gear Training (January/February 1998)

Gearing is a self-training course for teaching the basic fundamentals of gears and gearing to those totally unfamiliar with the subject.

590 Product Liability for Engineers (July/August 1998)

This textbook, written for college level engineering students, gives a basic grounding in the complexities of product liability law. It also provides useful information to those of us involved in the manufacturing of gears and gear systems in that the fundamental concepts apply to all types of manufacturers.

591 The Basics of Gear Metrology and Terminology Part I (September/October 1998)

It is very common for those working in the gear manufacturing industry to have only a limited understanding of the fundamental principals of involute helicoid gear metrology, the tendency being to leave the topic to specialists in the gear lab. It is well known that quiet, reliable gears can only be made using the information gleaned from proper gear metrology.

592 The Gallery of Fame: A Tribute to Gear Pioneers (March/April 1999)

The Gear Research Laboratory of the University of Illinois at Chicago is home to a unique tribute to gear pioneers from around the world, the Gallery of Fame. The gallery is the brainchild of the laboratory director, Professor Faydor L. Litvin. The Gallery was begun in 1994 an dis a photographic tribute to those gear company founders, inventors and researchers who devoted their careers to the study and development of gears.

593 Hard Gear Finishing with a Geometrically Defined Cutting Edge (November/December 1999)

The market demand for gear manufacturers to transmit higher torques via smaller-sized gear units inevitably leads to the use of case-hardened gears with high manufacturing and surface quality. In order to generate high part quality, there is an increasing trend towards the elimination of the process-induced distortion that occurs during heat treatment by means of subsequent hard finishing.

594 Gear Teeth With Byte (January/February 1998)

Computers are everywhere. It's gotten so that it's hard to find an employee who isn't using one in the course of his or her day - whether he be CEO or salesman, engineer or machinist. Everywhere you look, you find the familiar neutral-colored boxes and bright glowing screens. And despite the gear industry's traditional reluctance to embrace new technology, more and moe of what you find on those screens are gears.

595 Gear Crack Propagation Investigations (November/December 1997)

A common design goal for gears in helicopter or turboprop power transmission is reduced weight. To help meet this goal, some gear designs use thin rims. Rims that are too thin, however, may lead to bending fatigue problems and cracks. The most common methods of gear design and analysis are based on standards published by the American Gear Manufacturers Association. Included in the standards are rating formulas for gear tooth bending to prevent crack initiation (Ref. 1). These standards can include the effect of rim thickness on tooth bending fatigue (Ref 2.). The standards, however, do not indicate the crack propagation path or the remaining life once a crack has started. Fracture mechanics has developed into a useful discipline for predicting strength and life of cracked structures.

596 The Jewels In the (Gear) Crown (January/February 1998)

Over the years the Addendum Staff has brought you odd, little known and sometimes useless facts about almost every conceivable topic concerning gears. This month, as part of our never-ending campaign to upgrade the tone of the industry, we are venturing into the world of high fashion. Lose those pocket protectors, gear fans. Welcome to the land of gear haute couture. Appearing now, in select magazines, are ads that rival those of Bulgari, Cartier and Tiffany. These gear "gems" come courtesy of Winzeler Gear, Chicago, IL.

597 Low Vibration Design on A Helical Gear Pair (January/February 2000)

Helical gear pairs with narrow face width can be theoretically classified into three categories over the contact ration domain whose abscissa is the transverse contact ration and whose ordinate is the overlap contact ratio. There is a direct relation between vibration magnitude and shaft parallelism deviation. To clarify the effect of the tooth deviation types on the vibration behavior of helical gear pairs, performance diagrams on vibration are introduced. the acceleration levels of gear pairs are shown by contour lines on the contact ratio domain. Finally, the performance of gears with bias-in and bias-out modifications is discussed considering the effect of the shaft parallelism deviation with use of the developed simulator on a helical gear unit. It becomes clear that there is an asymmetrical feature on the relation between the vibration magnitude of a gear pair and the direction of each deviation.

598 Coordinate Measuring Machines and the Gear Industry (November/December 1999)

Gears are extremely complex shapes. Coordinate measuring machines, or CMMs, are designed to measure complex shapes. It seems to follow that CMMs world, therefore, be the ideal tool for measuring gears. But the answer is not so simple.

599 The Effect of Material Defects on Gear Perfomance - A Case Study (March/April 2000)

The quality of the material used for highly loaded critical gears is of primary importance in the achievement of their full potential. Unfortunately, the role which material defects play is not clearly understood by many gear designers. The mechanism by which failures occur due to material defects is often circuitous and not readily apparent. In general, however, failures associated with material defects show characteristics that point to the source of the underlying problem, the mechanism by which the failure initiated, and the manner in which it progressed to failure of the component.

600 Arrow Gear: Spiral Bevel Specialist (July/August 2003)

James J. Cervinka and Frank E. Pielsticker must've known the future when they named their new business Arrow Gear Co. in 1947. They started out to manufacture gears for hand tools and machine tools, but their business has taken off since then.

601 Gear Macrogeometry (September/October 2015)

I have outsourced gear macrogeometry due to lack of resources. Now I received the output from them and one of the gears is with —0.8× module correction factor for m = 1.8 mm gear. Since bending root stress and specific slide is at par with specification, but negative correction factor —0.8× module — is quite high — how will it influence NVH behavior/transmission error? SAP and TIF are very close to 0.05 mm; how will that influence the manufacturing/cost?

602 Local Simulation of the Specific Material Removal Rate for Generating Gear Grinding (September/October 2015)

Generating gear grinding is one of the most important finishing processes for small and medium-sized gears, its process design often determined by practical knowledge. Therefore a manufacturing simulation with the capability to calculate key values for the process — such as the specific material removal rate — is developed here. Indeed, this paper presents first results of a model for a local analysis of the value. Additionally, an empirical formula — based on a multiple regression model for a global value describing the process — is provided.

603 Hybrid Hertzian and FE-Based Helical Gear-Loaded Tooth Contact Analysis and Comparison with FE (July 2016)

Gear-loaded tooth contact analysis is an important tool for the design and analysis of gear performance within transmission and driveline systems. Methods for the calculation of tooth contact conditions have been discussed in the literature for many years. It's possible the method you've been using is underestimating transmission error in helical gears. Here's why.

604 Bevel Grinding Rolling Right Along (June 2015)

When Dr. Hermann J. Stadtfeld speaks, people tend to listen. Considered one of the world’s foremost experts on bevel gears, Stadtfeld, the vice president of bevel gear technology at Gleason, recently revealed several cutting-edge advancements that the company has been working on.

605 Gear Mesh Assembly (May 2015)

When assembling a pair of gears, what is a good method for setting and checking their mesh?

606 Innovative Induction Hardening Process with Pre-heating for Improved Fatigue Performance of Gear Component (July 2014)

Contact fatigue and bending fatigue are two main failure modes of steel gears, while surface pitting and spalling are two common contact fatigue failures -- caused by alternating subsurface shear stresses from the contact load between two gear mates. And when a gear is in service under cyclic load, concentrated bending stresses exist at the root fillet -- the main driver of bending fatigue failures. Induction hardening is becoming an increasingly popular response to these problems, due to its process consistency, reduced energy consumption, clean environment and improved product quality -- but not without issues of its own (irregular residual stresses and bending fatigue). Thus a new approach is proposed here that flexibly controls the magnitude of residual stress in the regions of root fillet and tooth flank by pre-heating prior to induction hardening. Using an external spur gear made of AISI 4340 as an example, this new concept/process is demonstrated using finite element modeling and DANTE commercial software.

607 Non-Involute Gearing, Function and Manufacturing Compared to Established Gear Designs (January/February 2015)

Introduction The standard profile form in cylindrical gears is an involute. Involutes are generated with a trapezoidal rack — the basis for easy and production-stable manufacturing (Fig. 1).

608 3-D Printing: We Ain't Seen Nothing Yet (March/April 2015)

NASA is now 3-D-printing spare parts up at the ISS (International Space Station). And in zero-gravity environments. And some of these parts are small gears and actuators, for starters. Every indication is that the list of power transmission-type parts to be converted will soon grow.

609 Managing Shop Floor Data (September/October 2016)

There’s no substitute for a good software package in gear manufacturing. It’s a critical shop floor tool that provides practical engineering services that customers appreciate. When you’re in the business of specifying and procuring high quality gears, the software needs to meet many objectives including the consideration of all tolerances of center distance, tooth thickness and tip diameters, root diameters, fillets, etc. It’s also imperative that the software updates include the latest revisions to the gear standards being used in the industry.

610 Oil-Out Endurance Under the Lens (January/February 2017)

Oil-out conditions, or conditions in which an aircraft is operating without any oil in its gearbox or transmission, are devastating for an aircraft's hardware. Even the sturdiest gears usually can’t last 30 minutes under such conditions before they catastrophically fail, and the whole system usually follows shortly after. That doesn’t leave pilots with a whole lot of time to find a suitable location to land in the case of an oil-out emergency.

611 Ask Not What Your Heat Treater Can Do for You... (July 2017)

When sending gears to be heat treated, manufacturers can end up unwittingly making mistakes that slow down turnaround time. We talked to some heat treaters to get their best advice on how you can help them help you.

612 Contact Fatigue Characterization of Through-Hardened Steel for Low-Speed Applications like Hoisting (July 2017)

In several applications like hoisting equipment and cranes, open gears are used to transmit power at rather low speeds (tangential velocity < 1m/s) with lubrication by grease. In consequence those applications have particularities in terms of lubricating conditions and friction involved, pairing of material between pinion and gear wheel, lubricant supply, loading cycles and behavior of materials with significant contact pressure due to lower number of cycles.

613 Much Ado About Nothing (July 2017)

For over 50 years, the Do Nothing Machine has entertained the public eye with its complex machinery, a mountain of over 700 gears put together for the express purpose of doing nothing.

614 Gear Inspection at Light Speed (July 2017)

Revolutionary new inspection technologies are helping gear manufacturers develop and produce more complex, higher quality gears in a fraction of the time it used to take.

615 Twist Control Grinding (June 2017)

This paper introduces the latest process developments for the hard-finishing of gears, specifically in regard to controlling the so-called flank twist.

616 5-Axis Gear Manufacturing Gets Practical (March/April 2017)

Exciting new machine, cutting tool and software technologies are compelling many manufacturers to take a fresh look at producing their larger gears on machining centers. They're faster than ever, more flexible, easy to operate, highly affordable - and for any type of gear.

617 Universal Hobs (March/April 2017)

Another expert takes a crack at a previously answered question about double-helical gears and universal hobs.

618 Gear Teeth as Bearing Surfaces (May 2017)

A reader wonders about gears where the tops of the teeth are the bearing surface, as used in spur gear differentials. Do they require any special construction or processing?

619 Gear Industry Heat Treat Resource Guide (July 2014)

Heat treating is one of the most critical operations in the manufacture of quality gears. Everything can be done to perfection, but if the heat treating isn’t right, all of your hard work and efforts are wasted. We know how important it is for gear manufacturers to find the right heat treating service provider. That’s why we’ve compiled this Heat Treat Resource Guide -- the only directory of heat treat service providers that’s specific to the gear industry. The companies listed here are all interested in working with gear manufacturers, and many of them have specialties and capabilities that are uniquely suited to the types of products you manufacture.

620 No Compromising on Quality at Allison Transmission (July 2014)

Gleason 350GMS helps put higher quality, more reliable gears into its next-generation TC10 automatic transmission.

621 Morphology of Micropitting (November/December 2012)

Understanding the morphology of micropitting is critical in determining the root cause of failure. Examples of micropitting in gears and rolling-element bearings are presented to illustrate morphological variations that can occur in practice.

622 The Involute Curve (January/February 2013)

Although gears can be manufactured using a wide variety of profiles, the involute curve is the most commonly used. Here are some of the basics.

623 DFM Crucial for Gear Industry Success (March/April 2013)

"Design for manufacturability" (DFM) is a well-established practice, essential to realizing the successful transformation of concepts into mass-produced gears and motion control devices. And yet, all too often issues that could have been avoided are identified very late in the process that impact production costs and schedules. This suggests that key DFM principles are often underutilized in practice and are not applied consistently - or to the degree necessary - to avoid these negative results.

624 IMTS 2012 Product Preview (September 2012)

Previews of manufacturing technology related to gears that will be on display at IMTS 2012.

625 Technology Mash-Up (August 2012)

The mind melds with gears for cycle project.

626 On a Possible Way of Size and Weight Reduction of a Car Transmission (July/August 2003)

Almost any external tooth form that is uniformly spaced around a center can be hobbed. Hobbing is recognized as an economical means of producing spur and helical gears with involute tooth profiles.

627 Meshing of a Spiral Bevel Gear Set With 3-D Finite Element Analysis (March/April 1997)

Recent advances in spiral bevel gear geometry and finite element technology make it practical to conduct a structural analysis and analytically roll the gear set through mesh. With the advent of user-specific programming linked to 3-D solid modelers and mesh generators, model generation has become greatly automated. Contact algorithms available in general purpose finite element codes eliminate the need for the use and alignment of gap elements. Once the gear set it placed in mesh, user subroutines attached to the FE code easily roll it through mesh. The method is described in detail. Preliminary result for a gear set segment showing the progression of the contact line load is given as the gears roll through mesh.

628 Powder Metal Magic (August 2012)

Capstan Atlantic, located in Wrentham, Massachusetts, produces powder metal gears, sprockets and complex structural components. The company has provided unique powder metal products in a variety of industries including automotive, business machines, appliances, lawn and garden equipment and recreational vehicles.

629 How Gear Hobbing Works (March/April 2013)

Hobbing is one of the most fundamental processes in gear manufacturing. Its productivity and versatility make hobbing the gear manufacturing method of choice for a majority of spur and helical gears.

630 Hardness Testing (May 2013)

This back-to-basics article describes the main methods used for hardness testing of gears: Rockwell, Brinell, Vickers and Knoop.

631 Gear Engineer by Day, Baritone by Night (January/February 2014)

When they’re not solving the latest mechanical engineering puzzle, the seven members of the group sINGer are busy engineering their voices to create the perfect sound. Yes, you read that correctly. Mechanical engineers do have hobbies outside of gears.

632 New ECM Furnace Improves Manufacture Efficiency of PM Components (March/April 2014)

The heat treatment processing of powder metal (PM) materials like Astaloy requires four steps -- de-waxing, HT sintering, carburizing and surface hardening -- which are usually achieved in dedicated, atmospheric furnaces for sintering and heat treat, respectively, leading to intermediate handling operations and repeated heating and cooling cycles. This paper presents the concept of the multi-purpose batch vacuum furnace, one that is able to realize all of these steps in one unique cycle. The multiple benefits brought by this technology are summarized here, the main goal being to use this technology to manufacture high-load transmission gears in PM materials.

633 Press Quenching and Effects of Prior Thermal History on Distortion during Heat Treatment (March/April 2014)

Precision components (industrial bearing races and automotive gears) can distort during heat treatment due to effects of free or unconstrained oil quenching. However, press quenching can be used to minimize these effects. This quenching method achieves the relatively stringent geometrical requirements stipulated by industrial manufacturing specifications. As performed on a wide variety of steel alloys, this specialized quenching technique is presented here, along with a case study showing the effects of prior thermal history on the distortion that is generated during press quenching.

634 Gear Standards and ISO GPS (October 2013)

In today’s globalized manufacturing, all industrial products having dimensional constraints must undergo conformity specifications assessments on a regular basis. Consequently, (standardization) associated with GD&T (geometrical dimensioning and tolerancing) should be un-ambiguous and based on common, accepted rules. Of course gears - and their mechanical assemblies - are special items, widely present in industrial applications where energy conversion and power transmission are involved.

635 Magnetic Gearing Attracting More Followers (August 2013)

"Going green" and energy efficiency are goals that all industries -- especially in Europe and the United States -- are working on, in such sectors as electric motors, lubrication, gears and on and on. Drumroll here please for magnetic gearing

636 Worn Gear Contact Analysis (June/July 2013)

How does one perform a contact analysis for worn gears? Our expert responds.

637 Wanted, Custom-Made Machine Tools (August 2013)

The machine tool industry is as competitive as ever. New machine technologies, materials, coatings and software upgrades are changing the way gears are being manufactured. Companies like Gleason, Liebherr, Kapp/Niles and DMG/Mori Seiki spend plenty of time and resources on R&D to develop the best products for the gear market. More importantly, these companies engage with (and listen to) customer requests.

638 The Gear Analysis Handbook by James L. Taylor Vibration Consultants Inc. (January/February 2002)

The author has written this book primarily from the viewpoint of analyzing vibrations on heavy industrial and mill gearing that may have been in service for a prolonged time. The purpose is to diagnose problems, especially the source or cause of failure. However, the principles and analysis techniques can be used for all types and sizes of gears, as well as for gear noise analysis.

639 Gear Software You Didn't Know About (January/February 1997)

Designing and manufacturing gears requires the skills of a mathematician, the knowledge of an engineer and the experience of a precision machinist. For good measure, you might even include the are of a magician, because the formulas and calculations involved in gear manufacturing are so obscure and the processes so little known that only members of an elite cadre of professionals can perform them.

640 The Art of Involutes (January/February 2012)

The Forest City Gear booth at Gear Expo featured a wide variety of gears utilized in medical equipment, Indy cars, fishing reels, even the recently launched Mars Rover. Scattered among Forest City’s products in Cincinnati were some unique gear sculptures created by an artist that finds more inspiration from the pages of industrial magazines than art galleries.

641 Advances in Quenching - A Discussion of Present and Future Technologies (March/April 2005)

Heat treating and quenching are arguably the most critical operations in the manufacture of gears. This article examines causes of distortion in heat treating and quenching.

642 Gear Design (May/June 1984)

A gear can be defined as a toothed wheel which, when meshed with another toothed wheel with similar configuration, will transmit rotation from one shaft to another. Depending upon the type and accuracy of motion desired, the gears and the profiles of the gear teeth can be of almost any form.

643 Identification and Correction of Damaging Resonances in Gear Drives (August/September 1984)

As a result of extensive research into the vibration characteristics of gear drives, a systematic approach has evolved, by which damaging resonances can be eliminated. The method combines finite element techniques with experimental signature and modal analyses. Implementation of the bulk of the method can be carried out early in the design stage. A step-by-step description of the approach, as it was applied to an existing accessory drive, is given in the text. It is shown how premature bearing failures were eliminated by detuning the torsional oscillations of a gearshaft. A dramatic reduction in vibration levels was achieved as a result of detuning the problem gear. The proposed approach can be extended to other types of rotating machines.

644 A Proposed Life Calculation for Micropitting (November/December 2011)

If you make hardened gears and have not seen any micropitting, then you haven’t looked closely enough. Micropitting is one of the modes of failure that has more recently become of concern to gear designers and manufacturers. Micropitting in itself is not necessarily a problem, but it can lead to noise and sometimes other more serious forms of failure. Predicting when this will occur is the challenge facing designers.

645 2011 AGMA Fall Technical Meeting (September 2011)

The AGMA Fall Technical Meeting provides an opportunity to share ideas with others on the design, analysis, manufacturing and application of gears, gear drives, and related products, as well as associated processes and procedures.

646 Gear Finishing by Shaving, Rolling and Honing, Part I (March/April 1992)

There are several methods available for improving the quality of spur and helical gears following the standard roughing operations of hobbing or shaping. Rotary gear shaving and roll-finishing are done in the green or soft state prior to heat treating.

647 Flank Load Carrying Capacity and Power Loss Reduction by Minimized Lubrication (May 2011)

The objective of this study was to investigate the limits concerning possible reduction of lubricant quantity in gears that could be tolerated without detrimental effects on their load carrying capacity.

648 Wind Turbines: Clean Energy, but Energy Efficient (June/July 2011)

We talked energy efficiency with some major players in the lubricants industry— but with a focus on their products’ impact regarding energy efficiency of gears and gearboxes in wind turbines.

649 Single-Flank Testing (October/November 1984)

It was very interesting to see Robert Smith's article on single-flank testing of gears...

650 Gear Design: Multipoint Properties are Key to Selecting Thermoplastic Materials (November/December 2006)

The palette of thermoplastic materials for gears has grown rapidly, as have the applications themselves. Designers need to be aware of key properties and attributes in selecting the right material.

651 Trends in Automobile Transmissions (July/August 2006)

With all the work in transmission development these days, the demand for automobile transmission gears should remain strong for several years, but suppliers will have to be as flexible as possible to keep up with the changes.

652 The Influence of Additive Chemistry on Micropitting (May/June 2005)

This article discusses the potential effects observed for different antiwear and EP chemistry on the micropitting of cylindrical gears.

653 Medical Device Manufacturing Keeps Gear Industry Healthy (March/April 2006)

When Forest City Gear started manufacturing gears for medical components in the 1980s, it was a minuscule part of the company's business. Today, the medical device industry represents 18-20%.

654 Gear Shaving - Process Simulation Helps to Comprehend an Incomprehensible Process (September/October 2006)

Due to its economical efficiency, the gear shaving process is a widely used process for soft finishing of gears. A simulation technique allows optimization of the process.

655 Optimization of the Gear Profile Grinding Process Utilizing an Analogy Process (November/December 2006)

In order to grind gears burn-free and as productively as possible, a better understanding of the process is required.

656 Optimum Number of Teeth for Span Measurement (May/June 1984)

An expression is derived, giving the optimum number of teeth over which the span measurement should be made, for profile-shifted spur and helical gears.

657 CNC Gear Shaping (March/April 1986)

Two major processes used for cutting gears, hobbing and shaping. This article describes advanced machine design and cutter materials for gear shaping.

658 Identification of Gear Noise with Single Flank Composite Measurement (May/June 1986)

Anyone involved in the design, manufacture and use of gears is concerned with three general characteristics relative to their application: noise, accuracy, and strength or surface durability. In the article, we will be dealing with probably the most aggravating of the group, gear noise.

659 Gear Research, The State of the Art (January/February 1985)

Gear research seems to be thriving. Between September 10th and October 17th, 120 papers about gears were presented at three conferences in Milwaukee, Boston, and Washington, to a total audience of about 400. The authors were from nine countries. Slightly more than half of the papers were prepared by authors who live outside the US and Canada.

660 Gear Chamfering Robot (January/February 2011)

Banyan Technologies introduces a robotic chamfering device suitable for deburring, chamfering and radiusing the edges of slew bearing ring gears.

661 Gear Garden Germinates from County's Industrial History (July 2008)

A new breed of blossoms sprouted this spring in York, PA cultivated from gears, sprockets, railroad spikes and other recycled metal items.

662 Influence of Grinding Burn on Pitting Capacity (August 2008)

This paper intends to determine the load-carrying capacity of thermally damaged parts under rolling stress. Since inspection using real gears is problematic, rollers are chosen as an acceptable substitute. The examined scope of thermal damage from hard finishing extends from undamaged, best-case parts to a rehardening zone as the worst case. Also, two degrees of a tempered zone have been examined.

663 Innovative Analysis and Documentation of Gear Test Results (September/October 2008)

In this paper, a method is presented for analyzing and documenting the pitting failure of spur and helical gears through digital photography and automatic computerized evaluation of the damaged tooth fl ank surface. The authors have developed an accurate, cost-effective testing procedure that provides an alternative to vibration analysis or oil debris methods commonly used in conjunction with similar test-rig programs.

664 Gear Data Exchange Format (March/April 2005)

VDI has created a data exchange format that allows for the electronic exchange of all geometric parameters for cylindrical gears.

665 Software Suite Serves Full Range of Gear Analysis (July 2008)

New software from AGMA helps gear designers calculate geometry and ratings for all types of bevel gears.

666 Opportunities for Gear Grinders - Insights from the Machinery Front (July/August 2005)

Tom Lang of Kapp Technologies shares his views on the trends affecting ground gears.

667 Making It in America: U.S. Manufacturing Is Alive, Well and Prospering (September/October 2005)

Most firms in the gear industry we've talked to over the past year are making more gears than ever, generating more sales, and filling up their schedule books into next year and beyond.

668 Study of the Correlation Between Theoretical and Actual Gear Fatigue Test Data on a Polyamide (June 2008)

In the past two years DSM has been conducting fatigue tests on actual molded gears in order to provide design data.

669 Mystery Gear on the Mountain (September/October 2008)

Gear on a mountain, you say? How can that be? Someone must be stricken with a bad case of altitude sickness to create that sort of delusion. What’s next, gears in space? On a glacier?

670 KISSsoft Update Integrates Parasolid CAD Core (May 2010)

The machine element package by KISSsoft for the design and optimization of components like gears, shafts, bearings and others is now available in the new version 04/2010.

671 Optimizing Gear Geometry for Minimum Transmission Error, Mesh Friction Losses and Scuffing Risk Through Computer- Aided Engineering (August 2010)

Minimizing gear losses caused by churning, windage and mesh friction is important if plant operating costs and environmental impact are to be minimized. This paper concentrates on mesh friction losses and associated scuffing risk. It describes the preliminary results from using a validated, 3-D Finite Element Analysis (FEA) and Tooth Contact Analysis (TCA) program to optimize cylindrical gears for low friction losses without compromising transmission error (TE), noise and power density. Some case studies and generic procedures for minimizing losses are presented. Future development and further validation work is discussed.

672 Application Examples from "Optimizing Gear Geometry for Minimum Transmission Error, Mesh Friction Losses and Scuffing Risk Through Computer- Aided Engineering" (August 2010)

Examples from gears in wind turbine, automotive and industrial applications.

673 Gear Fault Detection Effectiveness as Applied to Tooth Surface Pitting Fatigue Damage (November/December 2010)

A study was performed to evaluate fault detection effectiveness as applied to gear-tooth pitting-fatigue damage. Vibration and oil-debris monitoring (ODM) data were gathered from 24 sets of spur pinion and face gears run during a previous endurance evaluation study.

674 An Interview with Thomas Koepfer (August 2010)

Publisher Michael Goldstein sat down with Dr. Thomas Koepfer, whose family company, Josef Koepfer & Söhne GmbH, was founded in 1867. Over the years, the Koepfer name has become one of the best-known in the gear industry, with company operations including the manufacture of gear machines, cutting tools and gears.

675 Effects of Profile Corrections on Peak-to-Peak Transmission Error (July 2010)

Profile corrections on gears are a commonly used method to reduce transmission error, contact shock, and scoring risk. There are different types of profile corrections. It is a known fact that the type of profile correction used will have a strong influence on the resulting transmission error. The degree of this influence may be determined by calculating tooth loading during mesh. The current method for this calculation is very complicated and time consuming; however, a new approach has been developed that could reduce the calculation time.

676 Faster Honing to Mirror Fishises on Gear Faces and Bores (June 2010)

Stringent NVH requirements, higher loads and the trend towards miniaturization to save weight and space are forcing transmission gear designers to increasingly tighten the surface finish, bore size and bore-to-face perpendicularity tolerances on the bores of transmission gears.

677 The Anatomy of a Micropitting-Induced Tooth Fracture Failure (June 2010)

Micropitting has become a major concern in certain classes of industrial gear applications, especially wind power and other relatively highly loaded, somewhat slow-speed applications, where carburized gears are used to facilitate maximum load capacity in a compact package. While by itself the appearance of micropitting does not generally cause much perturbation in the overall operation of a gear system, the ultimate consequences of a micropitting failure can, and frequently are, much more catastrophic.

678 Gear Applications All the Rage at Windpower 2010 (June 2010)

Capitalizing on a burgeoning new technology where gears are of great import, the gear community gathered en masse at the American Wind Energy Association’s Windpower Expo 2010.

679 Cutting Fluid Selection and Process Controls for the Gear Manufacturing Industry (July/August 1987)

The last decade has been a period of far-reaching change for the metal working industry. The effect of higher lubricant costs, technical advances in machine design and increasing competition are making it essential that manufacturers of gears pay more attention to testing, selecting and controlling cutting fluid systems. Lubricant costs are not a large percentage of the process cost relative to items such as raw materials, equipment and labor, and this small relative cost has tended to reduce the economic incentive to evaluate and to change cutting fluids.

680 Rotary Gear Honing (May/June 1987)

Rotary gear honing is a hard gear finishing process that was developed to improve the sound characteristics of hardened gears by: Removing nicks and burrs; improving surface finish; and making minor corrections in tooth irregularities caused by heat-treat distortion.

681 Effects of Hob Quality and Resharpening Errors on Generating Accuracy (September/October 1987)

The modern day requirement for precision finished hobbed gears, coupled with the high accuracy characteristics of modern CNC hobbing machines, demands high tool accuracy.

682 Photography of Gear Failures (March/April 1994)

Photography is an essential part of gear failure analysis. It not only provides a fast, convenient way to accurately document the appearance of gear failure, but also is an effective diagnostic tool because the magnification obtained through photographic enlargement and slide projection often discloses evidence that may have been missed if the gears were not photographed.

683 An Innovative Way of Designing Gear Hobbing Processes (May 2012)

In today’s manufacturing environment, shorter and more efficient product development has become the norm. It is therefore important to consider every detail of the development process, with a particular emphasis on design. For green machining of gears, the most productive and important process is hobbing. In order to analyze process design for this paper, a manufacturing simulation was developed capable of calculating chip geometries and process forces based on different models. As an important tool for manufacturing technology engineers, an economic feasibility analysis is implemented as well. The aim of this paper is to show how an efficient process design—as well as an efficient process—can be designed.

684 Ask the Expert: High Ratio Hypoid Gear Efficiency (May 2012)

Our question this issue deals with high-ratio hypoid gears, and it should be noted here that this is a tricky area of gearing with a dearth of literature on the topic. That being the case, finding “experts” willing to stick their necks out and take on the subject was not a given.

685 High Speed Steel: Different Grades for Different Requirements (September/October 2004)

Hobs, broaches, shaper cutters, shaver cutters, milling cutters, and bevel cutters used in the manufacture of gears are commonly made of high speed steel. These specialized gear cutting tools often require properties, such as toughness or manufacturability, that are difficult to achieve with carbide, despite the developments in carbide cutting tools for end mills, milling cutters, and tool inserts.

686 Unsolved Gear Mysteries (January/February 2004)

If there is such a thing as a gear fairy, then it’s possible he makes surprise visits to various colleges to deposit gears under the pillows of deserving professors.

687 Dual Frequency Induction Gear Hardening (March/April 1993)

In the typical gear production facility, machining of gear teeth is followed by hear treatment to harden them. The hardening process often distorts the gear teeth, resulting in reduced and generally variable quality. Heat treating gears can involve many different types of operations, which all have the common purpose of producing a microstructure with certain optimum properties. Dual frequency induction hardening grew from the need to reduce cost while improving the accuracy (minimizing the distortion) of two selective hardening processes: single tooth induction and selective carburizing.

688 Viewpoint - Our Readers Respond (September/October 1994)

I support Clem Miller (Viewpoint May/June) in his skepticism of ISO 9000. The metrology of gears is important, but in the present state of the art, manufacture is more accurate than design.

689 Finding Gear Teeth Ratios (November/December 1985)

When designing gears, the engineer is often faced with the problem of selecting the number of teeth in each gear, so that the gear train will provide a given speed ratio

690 Eco-Friendly Cutting Fluids (May/June 1995)

Okay, so you want to make some high quality gears for your customers, and you want to make a profit for your company, but you don't want to make a mess of the environment. What can you do?

691 The Case of This Issue's Column (September/October 1995)

221B Baker Street We've always said that gears show up in all the best places, even, it turns out, among the papers of that most famous of detectives, Sherlock Holmes. "The Adventure of the Engineer's Thumb" is, according to Dr. Watson, a case "so strange in its inception and so dramatic in its details," that it merits a mention even in our exalted pages.

692 The Goof-Off Guide to Indy (November/December 1995)

Trade shows can be exhausting. You work hard all day, meeting people, wheeling and dealing, walking the aisles. After a long day of working the show, sometimes you just need to relax for awhile. With Gear Expo '95 fast approaching. Gear Technology has gone ahead and done some of the legwork for you. We've come up with some placed to go and things to do that have absolutely nothing to do with gears.

693 Mechanical Behavior and Microstructure of Ausrolled Surfaces in Gear Steels (March/April 1995)

Ausforming, the plastic deformation of heat treatment steels in their metastable, austentic condition, was shown several decades ago to lead to quenched and tempered steels that were harder, tougher and more durable under fatigue-type loading than conventionally heat-treated steels. To circumvent the large forces required to ausform entire components such as gears, cams and bearings, the ausforming process imparts added mechanical strength and durability only to those contact surfaces that are critically loaded. The ausrolling process, as utilized for finishing the loaded surfaces of machine elements, imparts high quality surface texture and geometry control. The near-net-shape geometry and surface topography of the machine elements must be controlled to be compatible with the network dimensional finish and the rolling die design requirements (Ref. 1).

694 Measurement Error Induced by Measuring over Pins Instead of Balls (January/February 1996)

The purpose of this article is to clarify some terms and methods used in measuring the size of gears. There is also an explanation given of the error induced and how to correct for it in certain cases when the measurement is made using pins instead of balls.

695 ADI - A Designer Gear Material (March/April 1995)

If someone were to tell you that he had a gear material that was stronger per pound than aluminum, as wear-resistant as steel, easier to machine than free-machining steel and capable of producing gears domestically for 20% less than those now cut from foreign made forgings, would you consider that material to be "high tech"? Probably. Well, throw out all the pre-conceived notions that you may have had about "high tech" materials. The high-performance material they didn't teach you about in school is austempered ductile iron (ADI).

696 Gleason Acquires Assets of Hurth (September/October 1995)

Rochester, NY - Gleason Corporation has acquired the assets of Hurth Maschinen and Werkzeuge GmbH, the designer and builder of cylindrical (parallel-axis) gear-making machinery and tooling based in Munich, Germany. The addition of Hurth gear shaving machines and tooling and gear honing machines will further broaden Gleason's expanding product line for manufacturers of cylindrical gears.

697 High Accurate Hobbing with Specially Designed Finishing Hobs (November/December 2003)

Load-carrying capacity of gears, especially the surface durability, is influenced by their tooth surface roughness in addition to their tooth profiles and tooth traces.

698 Gear Manufacturing in the Far East (January/February 2006)

This article gives readers a glimpse of some companies that manufacture gears in the Far East. We've talked with more than a dozen companies in India, Taiwan and Korea...

699 Hobbing Precise, Uniform End Chamfers (March/April 2004)

The seemingly simple process of placing a uniform chamfer on the face ends of spur and helical gears, at least for the aerospace industry, has never been a satisfactory or cost effective process.

700 Design of Oil-Lubricated Machine Components for Life and Reliability (November/December 2007)

This article summarizes the use of laboratory fatigue data for bearings and gears coupled with probabilistic life prediction and EHD theories to predict the life and reliability of a commercial turboprop gearbox.

701 Standard Issues (November/December 1996)

Standards are unlike gears themselves: mundane, but complex, ubiquitous and absolutely vital. Standards are a lingua franca, providing a common language with reference points for evaluating product reliability and performance for manufacturers and users. The standards development process provides a scientific forum for discussion of product design, materials and applications, which can lead to product improvement. Standards can also be a powerful marketing tool for either penetrating new markets or protecting established ones.

702 Hard Gear Finishing (March/April 1988)

Hard Gear Finishing (HGF), a relatively new technology, represents an advance in gear process engineering. The use of Computer Numerical Controlled (CNC) equipment ensures a high precision synchronous relationship between the tool spindle and the work spindle as well as other motions, thereby eliminating the need for gear trains. A hard gear finishing machine eliminates problems encountered in two conventional methods - gear shaving, which cannot completely correct gear errors in gear teeth, and gear rolling, which lacks the ability to remove stock and also drives the workpiece without a geared relationship to the master rolling gear. Such a machine provides greater accuracy, reducing the need for conventional gear crowning, which results in gears of greater face width than necessary.

703 A Real Test (July/August 1988)

It is often easy for those outside of the gear industry to get the impression that nothing is changing in our business. After all, all illustrated bimonthly by the covers of this very journal the making of gears has been with us for centuries. However, nothing could be further from the truth.

704 The Interrelationship of Tooth Thickness Measurements as Evaluated by Various Measuring Techniques (September/October 1987)

The first commandment for gears reads "Gears must have backlash!" When gear teeth are operated without adequate backlash, any of several problems may occur, some of which may lead to disaster. As the teeth try to force their way through mesh, excessive separating forces are created which may cause bearing failures. These same forces also produce a wedging action between the teeth with resulting high loads on the teeth. Such loads often lead to pitting and to other failures related to surface fatigue, and in some cases, bending failures.

705 CFD Technology for Rotorcraft Gearbox Windage Aerodynamics Simulation (August 2009)

A computational fluid dynamics (CFD) method is adapted, validated and applied to spinning gear systems with emphasis on predicting windage losses. Several spur gears and a disc are studied. The CFD simulations return good agreement with measured windage power loss.

706 The Effects of Surface Hardening on the Total Gear Manufacturing System (January/February 1991)

Carburized and hardened gears have optimum load-carrying capability. There are many alternative ways to produce a hard case on the gear surface. Also, selective direct hardening has some advantages in its ability to be used in the production line, and it is claimed that performance results equivalent to a carburized gear can be obtained. This article examines the alternative ways of carburizing, nitriding, and selective direct hardening, considering equipment, comparative costs, and other factors. The objective must be to obtain the desired quality at the lowest cost.

707 AGMA Responds to Gear Standards Article (January/February 1991)

The authors of last issue's article comparing AGMA, ISO and BS methods for Pitting Resistance Ratings are commended. Trying to compare various methods of rating gears is like hitting a moving target in a thick forest. The use of different symbols, presentations, terminology, and definitions in these standards makes it very difficult. But the greatest problem lies with the authors' use of older versions of these documents. ISO drafts and AGMA standards have evolved at the same time their work was accomplished and edited.

708 Automated Acoustic Intensity Measurements and the Effect of Gear Tooth Profile on Noise (March/April 1988)

The NASA Lewis Research Center investigated the effect of tooth profile on the acoustic behavior of spur gears through experimental techniques. The tests were conducted by Cleveland State University (CSU) in NASA Lewis' spur gear testing apparatus. Acoustic intensity (AI) measurements of the apparatus were obtained using a Robotic Acoustic Intensity Measurement System (RAIMS). This system was developed by CSU for NASA to evaluate the usefulness of a highly automated acoustic intensity measurement tool in the reverberant environment of gear transmission test cells.

709 AGMA, ISO, and BS Gear Standards Part I - Pitting Resistance Ratings (November/December 1990)

A study of AGMA 218, the draft ISO standard 6336, and BS 436: 1986 methods for rating gear tooth strength and surface durability for metallic spur and helical gears is presented. A comparison of the standards mainly focuses on fundamental formula and influence factors, such as the load distribution factor, geometry factor, and others. No attempt is made to qualify or judge the standards other than to comment on the facilities or lack of them in each standard reviewed. In Part I a comparison of pitting resistance ratings is made, and in the subsequent issue, Part II will deal with bending stress ratings and comparisons of designs.

710 Surface Damage Caused by Gear Profile Grinding and its Effects on Flank Load Carrying Capacity (September/October 2004)

Instances of damage to discontinuous form ground and surface-hardened gears, especially of large scale, have recently increased. This may be attributed partly to a faulty grinding process with negative effects on the surface zones and the surface properties.

711 Extending the Benefits of Elemental Gear Inspection (July 2009)

It may not be widely recognized that most of the inspection data supplied by inspection equipment, following the practices of AGMA Standard 2015 and similar standards, are not of elemental accuracy deviations but of some form of composite deviations. This paper demonstrates the validity of this “composite” label by first defining the nature of a true elemental deviation and then, by referring to earlier literature, demonstrating how the common inspection practices for involute, lead (on helical gears), pitch, and, in some cases, total accumulated pitch, constitute composite measurements.

712 The Sines of the Fathers (November/December 1995)

Your Addendum team has come across a number of Good Ole Boys in its time; now we bring you something of even more interest - a Good Ole Gear Book. Mr. Robert Price, of Automation - Gears - Machinery, a gear consulting firm in Delanson, NY, shared with us a real find.

713 Revolutions (November/December 2003)

"Holding Gears in Place for Quick Operations" and "Machine Broaches Unusual Sized Gears."

714 The Powder Metal Method (June 2008)

Despite economic uncertainty, the future looks promising for PM Gears.

715 Inreasing Hardness Through Cryogenics (March/April 1997)

The Instrumented Factory for Gears (INFAC) conducted a metallurgical experiment that examined the effects of carburizing process variables and types of cryogenic treatments in modifying the microstructure of the material. The initial experiment was designed so that, following the carburizing cycles, the same test coupons could be used in future experiment.

716 GT Extras (August 2014)

See the latest online video from Gleason, plus explore the THORS Academy Gears Knowledge Center and our Back to Basics archive.

717 GT Extras (March/April 2015)

This issue, GT Extras brings you "Heat Treat and Induction Hardening of Industrial Gears," a treasure trove of heat treating related technical articles and a call for help in preparation for AGMA's 100th anniversary.

718 Revolutions (March/April 2004)

"Gears of Gold" and "Process Equipment's Virtual ND430."

719 Towards an Improved AGMA Accuracy Classification System on Double-Flank Composite Measurements (June/July 2012)

AGMA introduced ANSI/AGMA 2015–2–A06— Accuracy Classification System: Radial System for Cylindrical Gears, in 2006 as the first major rewrite of the double-flank accuracy standard in over 18 years. This document explains concerns related to the use of ANSI/AGMA 2015–2–A06 as an accuracy classification system and recommends a revised system that can be of more service to the gearing industry.

720 Technical Calendar (May/June 1989)

May 18-21. AGMA Annual Meeting, "The Changing World of Gears." Loews Ventana Canyon Resort, Tucson, AZ. July 12-14, 1989. ASM international Conference on Carburizing. Sheraton Hotel & Conference Center, Lakewood, CO. September 12-20, 1989. European Machine Tool Show, Hannover, West Germany.

721 Events (May 2009)

Advance coverage of India's Gears, Motors & Controls Expo 2009, plus our regular calendar of events.

722 Watch This Space (January/February 1995)

Good References In the 7th Edition of McGraw Hill Encyclopedia of Science and Technology, 10 pages are devoted to the subjects of Gears, Gear Cutting and Gear Trains.

723 Sherlock Holmes and the Gear-Filled Weapons of Mass Destruction (May 2010)

What’s that sound? The churning of gear teeth meshing with the creak of film reels. A bit of “Holmesian deduction” leads us to the conclusion that it’s time for the next installment of the Addendum’s Gears in Film Series!

724 A Gear is a Gear is a Gear, Except When it Isnt (August 2015)

Look at that picture right over there on the right. That’s one of the Bronze Wheels of Peru. Looks like a gear, doesn’t it? If you knew nothing about it or the culture it sprang from and just happened to see it on the street, you’d probably label it as such. So many people have had that same thought, in fact, that the set has picked up another name: the Bronze Gears of Peru.

725 Introduction to ISO 6336 What Gear Manufacturers Need to Know (July/August 1998)

ISO 6336 Calculation of Load Capacity of Spur and Helical Gears was published in 1997 after 50 years of effort by an international committee of experts whose work spanned three generations of gear technology development. It was a difficult compromise between the existing national standards to get a single standard published which will be the basis for future work. Many of the compromises added complication to the 1987 edition of DIN 3990, which was the basic document.

726 AGMAs Go-To Gear Guys (September/October 2016)

While the two have taught a variety of AGMA courses over the years, without question their most popular courses are Gear Failure Analysis (Errichello with longtime colleague Jane Muller) and Gearbox CSI: Forensic Analysis of Gear & Bearing Failures (Drago). Drago currently teaches Manufacturing & Inspection (with AGMA instructor Joseph W. Lenski, Jr.) and Gearbox System Design: The Rest of the Story… Everything but the Gears and Bearings (with AGMA instructor Steve Cymbala) as well.

News Items About gears

1 KISSsoft Adds Beveloid Gears Module (October 28, 2014)
Beveloid gears have their own new module in the KISSsoft system (module ZH1). Sizing and dimensioning of beveloid gears have been impleme... Read News

2 Ondrives Launches Crossed Helical Gears (April 2, 2010)
A precision range of crossed helical gears was released from Ondrives Ltd. These 45 degree crossed helical gears have already been specia... Read News

3 KISSsoft Offers Fine Sizing for Worm Wheels and Crossed Helical Gears (September 25, 2013)
For the calculation of worm wheels and crossed helical gears, fine sizing modules are now available (module ZD5 and ZE6). The KISSsoft fi... Read News

4 Grieve Furnace Treats Large Gears (July 24, 2013)
No. 1030 is a 550ºF floor-level electric cabinet oven from Grieve, currently used for heating large gears at the customer’s fa... Read News

5 KISSsoft Extends Contact Analysis for Cylindrical Gears (October 9, 2013)
The contact analysis for cylindrical gears in KISSsoft (module ZA30) has been extended and improved. Experience gained from a comparison ... Read News

6 GE Oil and Gas to Acquire Allen Gears (December 12, 2013)
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7 mG miniGears Installs Furnace Loading System (June 25, 2007)
mG miniGears installed a furnace loading system in its powder metal department to avoid defects, especially for gears where small damage of the... Read News

8 DSM’s Stanyl Precison Gears Help Disabled Patients Drive Independently (April 11, 2006)
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9 Samputensili Master Gears Personalized to Customer or DIN Specifications (April 12, 2006)
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10 Stainless Steel Gears From QTC Features the Fairloc Integral Fastening System (October 6, 2008)
A new series of Modules 0.5, 0.8, and 1 spur gears from Quality Transmission Components features the patented Fairloc integral hub fast... Read News

11 One LMC Chuck Handles Over 40 Gears (October 27, 2009)
Specialty finger chucks from LMC Workholding are designed for hard turning gears on truck axles or drive line components. By changing pin... Read News

12 Sterling Instruments New Precision Internal Gears Selectable by Inches or Millimeters (April 30, 2006)
New precision internal gears from Sterling Instrument are available from stock in inch and metric sizes. The 20? pressure angle inch ... Read News

13 Sterling Instrument’s Anti-Backlash Gears Eliminate Marred Shafts (March 10, 2006)
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14 Gleason’s Newest Threaded Wheel Grinder Delivers Faster Floor-to-Floor Times for Cylindrical Gears up to 300 mm (February 13, 2007)
The 300 TWG from Gleason Corp. is designed to deliver fast floor-to-floor times for grinding of cylindrical gears with a diameter up to 3... Read News

15 KISSsoft Offers Contact Patterns of Five-Axis Milled Gears (November 6, 2013)
The five-axis milling of gears is an established manufacturing process in the field of short run and replacement parts. This manufacturi... Read News

16 New Instrumentation Gears from Precision Alliance (April 16, 2004)
A new line of specialty and instrumentation gears is now available from Precision Alliance and includes spur, segment, anti-backlash sync... Read News

17 KISSsoft Determines Misalignment of Bevel Gears in Latest Update (October 18, 2016)
The relative position of the pinion and the ring gear is critical in determining the wear patterns of bevel gears. To determine the bevel... Read News

18 Grieve No. 1030 Oven Provides Heat Treat for Large Gears (January 19, 2017)
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19 Gleason Renames its Plastic Gears Division (June 30, 2015)
Gleason Corporation recently announced a new name for its plastic gears division: Gleason Plastic Gears. The division was formerly k... Read News

20 Rush Gears Publishes New Gear Design Guide (January 7, 2005)
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21 mG miniGears Reports Sales Surpassing 70 Million Euros (February 2, 2007)
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22 Gleason’s New Threaded Grinder Optimizes Fine Finishing of Hard Spur and Helical Gears (January 2, 2007)
Gleason’s new Genesis 130TWG High Speed Threaded Wheel Grinder features a new design that reduces floor space requirements and impro... Read News

23 New Facility, Markets for Kleiss Gears (April 16, 2004)
Kleiss Gears has traded in their 3,000 square foot facility in Centerville, MN, for a 14,000 square foot building in Grantsburg, WI. ... Read News

24 Ronson Gears Wins Apprenticeship Award (February 14, 2007)
Ronson Gears was named a winner at the Melbourne Business Awards 2006 Foundation. The Melbourne Business Awards commenced in 1992 to ... Read News

25 Shanthi Gears Opens Office in Germany (February 14, 2006)
To better serve the European market, Shanthi Gears opened an office near D?sseldorf, Germay. Mr. Milroy Bede Nicholas will serve as li... Read News

26 Kleiss Gears Accredited to ISO 9001 (March 10, 2006)
Kleiss Gears announced its recent accreditation to ISO 9001. According to Rod Kleiss, company president, the certification was necessa... Read News

27 mG miniGears Officially Opens in China (January 17, 2004)
mG miniGears in Suzhou, China is now open and operating at full capacity. According to the company’s press release, the Chinese o... Read News

28 Matlab Increases Heat Treating Capaciy for Gears (January 4, 2005)
Metlab has completed the upgrade of one of its large pit carburizing furnaces, which doubles its capabilities for carburizng, nitriding, ... Read News

29 EMCO Gears On Track with Expansion (April 26, 2006)
EMCO Gear Co. has opened a second plant facility, located in Mooresville, NC and right in the heart of Grand American Road Racing country... Read News

30 mG miniGears Acquires New Furnace (March 9, 2005)
mG miniGears acquired a high temperatures furnace that can perform at 1,300 degrees C sintering temperature. According to the company&... Read News

31 Magnetic Gearing and Turbine Corp. Releases New Injection Molded Plastic Gears (April 6, 2006)
Magnetic Gearing & Turbine Corporation of Australia annonced the release of a new generation injection moulded magnetic gear. Accordi... Read News

32 Flowserve Introduces New Models to PT Series Worm Gears (April 13, 2005)
Flowserve Corp., a provider of fluid motion and control products and services, added two new sizes to the Flowserve Limitorque PT series ... Read News

33 Norton’s New Gear Grinding Wheels Increase Life of Parallel Axis Spur Gears (April 11, 2006)
The new BRGg VPHS high speed grinding wheels from Saint Gobain are designed to reduce cycle times by increasing metal removal rates. The ... Read News

34 Bison Gears Adds Custom AC Motors (March 15, 2006)
Bison Gear and Engineering plans to begin manufacturing their own line of AC motors in their St. Charles, IL, facility beginning in April... Read News

35 Rush Gears Introduces Gear Gages (April 19, 2006)
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36 mG miniGears Named One of Europe’s Fastest Growing Companies (April 15, 2006)
mG miniGears SpA of Padua announced that it has been listed No. 272 among the fastest growing European companies included in the 2006 Eur... Read News

37 Moventas Receives Order for Mass Deliveries of Wind Turbine Gears to Acciona (January 14, 2006)
Moventas signed a supply agreement for substantial deliveries of wind turbine gearbo... Read News

38 Combined Process Machine Completes Cylindrical Gears (January 26, 2010)
The Agilus 180TH multi-functional machine from Gleason performs turning, drilling, milling, hobbing and chamfering/deburring operatio... Read News

39 EFD Induction Awarded Orders for Induction Scanners to Harden Sun Gears and Output Shafts (May 26, 2015)
EFD Induction USA has recently won major orders from two American tier-one automotive suppliers.The orders involve EFD Induction ‘H... Read News

40 Index 'Bevel Gear Hobbing Package' Produces Gears With Tooth Height in a Module Range of 0.6 to 4 mm (July 17, 2015)
Index recently developed a “bevel gear hobbing” package, which consists of a control cycle and four Index cutter heads with m... Read News

41 Santasalo Launches Quatro+ Planetary Gears (May 18, 2015)
Santasalo recently introduced their new series of planetary gear units to the global industrial market. The new Quatro+ range offers high... Read News

42 AKGears Unveils Latest Tooth Root Fillet Optimization Software (April 14, 2015)
AKGears recently introduced the only commercially available tooth root fillet optimization software that defines the tooth root fillet pr... Read News

43 Arrow Gear Becomes Distributor for SAMP Gears (December 9, 2014)
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44 Suhner Spiral Bevel Gears Offer High Power, Low Backlash and Low Noise (August 21, 2015)
Each year, increased engine and motor power require more powerful angle gear heads. Engineers in the tool-making and industrial hand too... Read News

45 Samputensili SG 160 Sky Grind Introduces Dry Grinding of Gears to Star SU Line (December 24, 2015)
Samputensili has recently launched a world premiere at EMO Milan 2015. The new machine, the SG 160 Sky Grind, is designed to eliminate th... Read News

46 Mitsubishi Heavy Industries MSS300 Skiving Machine Designed for Manufacturing Automotive Internal Ring Gears (December 15, 2016)
The opening of the JIMTOF machine tool show in Tokyo, Japan marked the debut of MHIMTC's new MSS300 super skiving gear machine. This ... Read News

47 GWJ Technology Offers New Calculation Modules for Cylindrical Gears (June 22, 2016)
GWJ Technology GmbH, a manufacturer of calculation software for machine elements and gearboxes, has upgraded its web-based calculation so... Read News

48 KISSsoft Offers Strength Analysis for Cylindrical Gears (March 24, 2016)
The strength calculation method specified in Lloyd's Register:2013 has now been implemented. This specific standard for ships is now ... Read News

49 MS3D GearInspection Creates 3D Scan of Gears in Under 10 Seconds (February 19, 2016)
In cooperation with various universities, the French manufacturer Mesure-Systems-3D (MS3D) has developed a contactless in line testing sy... Read News

50 Quality Transmission Components Rebranded as QTC Metric Gears (November 10, 2014)
Designatronics, Inc., a provider of complete mechatronic engineered solutions and services to the aerospace and defense, robotics, pac... Read News

51 Ronson Gears Recognized with Enterprise Award (May 17, 2013)
Victorian gear manufacturer Ronson Gears was recently announced winner of the “Enterprise Connect Significant Achievement Award&rdq... Read News

52 Junker JUMAT Machine Offers Simultaneous Grinding of ID, OD and Faces of Gears (May 31, 2017)
Junker has introduced the JUMAT 6S 18-20S-18, the latest of Junker's JUMAT series of modular grinding machines, which is capable of g... Read News

53 DTR Offers Hobs for Cutting Wind Turbine and Heavy Industrial Gears (January 21, 2010)
DTR Corporation recently announced its full line of high-performance, large coarse pitch hobs for cutting wind turbine and heavy industri... Read News

54 Versatile Reishauer Grinder Adapted for Larger Gears (December 28, 2009)
The RZ 260 gear grinding machine from Reishauer is based on the successful RZ 150 series, but not only has size been increased, but all c... Read News

55 Carraro Group Finalizes Takeover of mG miniGears (August 3, 2007)
Gear World SpA, a newly established company, put the finishing touches on its 100% takeover of mG holding SpA, the controlling company of... Read News

56 KISSsoft Releases New Function for Face Gears (September 9, 2010)
A new functionality to generate a solid model of a face gear with arbitrary shaft angle and offset is implemented in the development vers... Read News

57 Hi-Tech Gears Wins Shingo Silver Medallion (September 29, 2010)
13 recipients were recently awarded the Shingo Prize for Operational Excellence including Hi-Tech Gears Limited, located in Haryana, Indi... Read News

58 LMT Fette Focuses on Efficiency in Large Gears (November 30, 2012)
The market for large gear wheels is growing – in a great variety of industries: wind turbines, construction vehicles and ships need... Read News

59 NTN Develops Technology for Powder Metal Gears (March 28, 2012)
NTN Corporation has developed a manufacturing technology for sintered alloy, capable of manufacturing alloy with an absolute density rati... Read News

60 Tester Measures Camshafts with Gears (October 10, 2011)
An upgraded camshaft measuring machine that is designed with a wide diameter offset follower to accommodate larger diameter cams with bui... Read News

61 Luren's LFG-8040 Grinds Spur and Helical Gears (January 19, 2011)
The most recent development from Luren Precision Co., Ltd. is the vertical type CNC gear profile grinding machine, LFG-8040, th... Read News

62 BHS Rotor Turning Gears Showcased at PowerGen Europe (June 13, 2007)
BHS Getriebe GmbH will be showcasing its rotor turning gear capabilities in its booth at Power Gen Europe.Units are used to prevent ... Read News