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Articles About rating


1 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 formulae 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.

2 Review of Gear Standards - Part II (January/February 1991)

In Part I differences in pitting ratings between AGMA 218, the draft ISO standard 6336, and BS 436:1986 were examined. In this part bending strength ratings are compared. All the standards base the bending strength on the Lewis equation; the ratings differ in the use and number of modification factors. A comprehensive design survey is carried out to examine practical differences between the rating methods presented in the standards, and the results are shown in graphical form.

3 Operating Pressure Angle (May 2013)

What is the difference between pressure angle and operating pressure angle?

4 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.

5 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.

6 Comparing Standards (September/October 1998)

One of the best ways to learn the ISO 6336 gear rating system is to recalculate the capacity of a few existing designs and to compare the ISO 6336 calculated capacity to your experience with those designs and to other rating methods. For these articles, I'll assume that you have a copy of ISO 6336, you have chosen a design for which you have manufacturing drawings and an existing gear capacity calculation according to AGMA 2001 or another method. I'll also assume that you have converted dimensions, loads, etc. into the SI system of measurement.

7 Calculating Spur and Helical Gear Capacity with ISO 6336 (November/December 1998)

This is the third article in a series exploring the new ISO 6336 gear rating standard and its methods of calculation. The opinions expressed herein are htose of the author as an individual. They do not represent the opinions of any organization of which he is a member.

8 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.

9 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.

10 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.

11 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.

12 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.

13 Computerized Hob Inspection & Applications of Inspection Results - Part I (May/June 1994)

Can a gear profile generated by the hobbing method be an ideal involute? In strictly theoretical terms - no, but in practicality - yes. A gear profile generated by the hobbing method is an approximation of the involute curve. Let's review a classic example of an approximation.

14 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.

15 AGMA and ISO Accuracy Standards (May/June 1998)

The American Gear Manufacturers Association (AGMA) is accredited by the American National Standards Institute (ANSI) to write all U.S. standards on gearing. However, in response to the growing interest in a global marketplace, AGMA became involved with the International Standards Organization (ISO) several years ago, first as an observer in the late 1970s and then as a participant, starting in the early 1980s. In 1993, AGMA became Secretariat (or administrator) for Technical Committee 60 of ISO, which administers ISO gear standards development.

16 Computerized Hob Inspection & Applications of Inspection Results Part II (July/August 1994)

Flute Index Flute index or spacing is defined as the variation from the desired angle between adjacent or nonadjacent tooth faces measured in a plane of rotation. AGMA defines and provides tolerance for adjacent and nonadjacent flute spacing errors. In addition, DIN and ISO standards provide tolerances for individual flute variation (Fig. 1).

17 Comparison of Rating Trends in AGMA Versus ISO (May/June 2004)

As the international business community grows closer together, the need for understanding differences between national and international gear rating standards becomes increasingly important for U.S. gear manufacturers competing in the world market.

18 The Effect of Start-Up Load Conditions on Gearbox Performance and Life Failure Analysis, With Supporting Case Study (June 2009)

If a gear system is run continuously for long periods of time—or if the starting loads are very low and within the normal operating spectrum—the effect of the start-up conditions may often be insignificant in the determination of the life of the gear system. Conversely, if the starting load is significantly higher than any of the normal operating conditions, and the gear system is started and stopped frequently, the start-up load may, depending on its magnitude and frequency, actually be the overriding, limiting design condition.

19 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.

20 Induction Heat Trating: Things Remembered, Things Forgotten (March/April 1997)

Many potential problems are not apparent when using new induction heat treating systems. The operator has been trained properly, and setup parameters are already developed. Everything is fresh in one's mind. But as the equipment ages, personnel changes or new parts are required to be processed on the old equipment ages, personnel changes or new parts are required to b processed on the old equipment, important information can get lost in the shuffle.

21 Dynamic Loads in Parallel Shaft Transmissions - Part 2 (May/June 1990)

Solutions to the governing equations of a spur gear transmission model, developed in a previous article are presented. Factors affecting the dynamic load are identified. It is found that the dynamic load increases with operating speed up to a system natural frequency. At operating speeds beyond the natural frequency the dynamic load decreases dramatically. Also, it is found that the transmitted load and shaft inertia have little effect upon the total dynamic load. Damping and friction decrease the dynamic load. Finally, tooth stiffness has a significant effect upon dynamic loadings the higher the stiffness, the lower the dynamic loading. Also, the higher the stiffness, the higher the rotating speed required for peak dynamic response.

22 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.

23 The Gear Hobbing Process (January/February 1994)

Gear hobbing is a generating process. The term generating refers to the fact that the gear tooth form cut is not the conjugate form of the cutting tool, the hob. During hobbing both the hob and the workpiece rotate in a continuous rotational relationship. During this rotation, the hob is typically fed axially with all the teeth being gradually formed as the tool traverses the work face (see Fig. 1a).

24 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.

25 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.

26 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.

27 A Method for Obtaining Optimum Gear Tooth Microtopographies for Noise and Stress Minimization Over a Broad Operating Torque Range (July 2008)

A graphical procedure for selecting optimum combinations of profile and lead modifications.

28 Generating Interchangeable 20-Degree Spur Gear Sets with Circular Fillets to Increase Load Carrying Capacity (July/August 2006)

This article presents a new spur gear 20-degree design that works interchangeably with the standard 20-degree system and achieves increased tooth bending strength and hence load carrying capacity.

29 Celebrating 20 Years (May/June 2004)

A look back at Gear Technology's first 20 years and how the gear industry has changed.

30 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.

31 Accelerating Validation Testing (January/February 2012)

Bringing new or improved products to market sooner has long been proven profitable for companies. One way to help shorten the time-to-market is to accelerate validation testing. That is, shorten the test time required to validate a new or improved product.

32 Generating and Checking Involute Gear Teeth (May/June 1986)

It has previously been demonstrated that one gear of an interchangeable series will rotate with another gear of the same series with proper tooth action. It is, therefore, evident that a tooth curve driven in unison with a mating blank, will "generate" in the latter the proper tooth curve to mesh with itself.

33 The European Rack Shift Coefficient 'X' for Americans (July/August 1993)

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.

34 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.

35 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.

36 Classification of Types of Gear Tooth Wear - Part I (November/December 1992)

The phenomena of deterioration of surfaces are generally very complex and depend on numerous conditions which include the operating conditions, the type of load applied, the relative speeds of surfaces in contact, the temperature, lubrication, surfaces hardness and roughness, and the compatibility and nature of materials.

37 Innovative CNC Gear Shaping (January/February 1994)

The Shaping Process - A Quick Review of the Working Principle. In the shaping process, cutter and workpiece represent a drive with parallel axes rotating in mesh (generating motion) according to the number of teeth in both cutter and workpiece (Fig. 1), while the cutter reciprocates for the metal removal action (cutting motion).

38 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.

39 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.

40 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.

41 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.

42 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).

43 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.

44 EHL Film Thickness, Additives and Gear Surface Fatigue (May/June 1995)

Aircraft transmissions for helicopters, turboprops and geared turbofan aircraft require high reliability and provide several thousand hours of operation between overhauls. In addition, They should be lightweight and have very high efficiency to minimize operating costs for the aircraft.

45 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.

46 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.

47 What the Internet Means To Your Gear Business (July/August 1998)

Let's face it. The Internet is still, to many of us, exciting, confusing, terrifying and frustrating by turns. The buzzwords change so fast that even the most high tech companies have a hard time keeping up. Cyberspace. Firewall, Java. E-commerce. The list goes on.

48 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.

49 Obtaining Meaningful Surface Roughness Measurements on Gear Teeth (July/August 1997)

Surface roughness measuring of gear teeth can be a very frustrating experience. Measuring results often do not correlate with any functional characteristic, and many users think that they need not bother measuring surface roughness, since the teeth are burnished in operation. They mistakenly believe that the roughness disappears in a short amount of time. This is a myth! The surface indeed is shiny, but it still has considerable roughness. In fact, tests indicate that burnishing only reduces the initial roughness by approximately 25%.

50 Involute Inspection Methods and Interpretation of Inspection Results (July/August 1997)

What is so unique about gear manufacturing and inspection? Machining is mostly associated with making either flat or cylindrical shapes. These shapes can be created by a machine's simple linear or circular movements, but an involute curve is neither a straight line nor a circle. In fact, each point of the involute curve has a different radius and center of curvature. Is it necessary to go beyond simple circular and linear machine movements in order to create an involute curve? One of the unique features of the involute is the fact that it can be generated by linking circular and linear movements. This uniqueness has become fertile soil for many inventions that have simplified gear manufacturing and inspection. As is the case with gear generating machines, the traditional involute inspection machines take advantage of some of the involute properties. Even today, when computers can synchronize axes for creating any curve, taking advantage of involute properties can be very helpful. I t can simplify synchronization of machine movements and reduce the number of variables to monitor.

51 The SERCOS Interface Standard (January/February 1996)

Today motion control systems are migrating from analog to digital technology at an ever increasing rate because digital technology at an ever-increasing rate because digital drives provide performance equal to or exceeding that of analog drives, plus information to run your machine more effectively and manage your quality program and your business. Most of this data is simply not available from analog drives.

52 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.

53 Gearbox Field Performance From a Revuilder's Perspective (May/June 2001)

The major focus of the American Gear Manufacturers Association standards activity has been the accurate determination of a gearbox's ability to transmit a specified amount of power for a given amount of time. The need for a "level playing field" in the critical arena was one of the reasons the association was formed in the first place. Over the past 85 years, AGMA committees have spent countless hours "discussing" the best ways to calculate the rating of a gear set, often arguing vigorously over factors that varied the resulting answers by fractions of a percentage point. While all that "science" was being debated in test labs and conference rooms all over the country, out industry's customers were conducting their own experiments through the daily operation of gear-driven equipment of all types.

54 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.

55 ISO 6336-5: Strength and Quality of Materials (January/February 1999)

This is the fourth and final article in a series exploring the new ISO 6336 gear rating standard and its methods of calculation. The opinions expressed herein are those of the author as an individual. They do not represent the opinions of any organization of which he is a member.

56 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.

57 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...

58 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.

59 Geezer World Party On! (September/October 2006)

It's unlikely that AARP will find itself in a revenue-generating crisis, but if it occurs, Fred Young of Forest City Gear in Roscoe, IL, is the man with the plan.

60 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.

61 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.

62 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.

63 The Effect of Manufaturing Microgeometry Variations on the Load Distribution Factor and on Gear Contact and Root Stresses (July 2009)

Traditionally, gear rating procedures consider manufacturing accuracy in the application of the dynamic factor, but only indirectly through the load distribution are such errors in the calculation of stresses used in the durability and gear strength equations. This paper discusses how accuracy affects the calculation of stresses and then uses both statistical design of experiments and Monte Carlo simulation techniques to quantify the effects of different manufacturing and assembly errors on root and contact stresses.

64 Gear Heat Treatment: The Influence of Materials and Geometry (March/April 2004)

Gear designs are evolving at an ever accelerating rate, and gear manufacturers need to better understand how the choice of materials and heat treating methods can optimize mechanical properties, balance overall cost and extend service life.

65 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.

66 Tooth Forms for Hobs (March/April 1985)

The gear hobbing process is a generating type of production operation. For this reason, the form of the hob tooth is always different from the form of the tooth that it produces.

67 Involute Spline Size Inspection (March/April 1985)

This article describes a new technique for the size determination of external Involute splines by using a span measuring method. It provides application performance information demonstrating how this method and its measurements correlate with the traditional spline ring gage sizing method.

68 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.

69 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.

70 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.

71 Involutometry Illustrations (November/December 1988)

In our last issue, the labels on the drawings illustrating "Involutometry" by Harlan Van Gerpan and C. Kent Reece were inadvertently omitted. For your convenience we have reproduced the corrected illustrations here. We regret any inconvenience this may have caused our readers.

72 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.

73 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.

74 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.

75 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.

76 Selection of Material and Compatible Heat Treatments for Gearing (May/June 1986)

The manufacturing process to produce a gear essentially consist of: material selection, blank preshaping, tooth shaping, heat treatment, and final shaping. Only by carefully integrating of the various operations into a complete manufacturing system can an optimum gear be obtained. The final application of the gear will determine what strength characteristics will be required which subsequently determine the material and heat treatments.

77 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.

78 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.

79 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.

80 Hard Finishing and Fine Finishing Part 1 (September/October 1989)

Profitable hard machining of tooth flanks in mass production has now become possible thanks to a number of newly developed production methods. As used so far, the advantages of hard machining over green shaving or rolling are the elaborately modified tooth flanks are produced with a scatter of close manufacturing tolerances. Apart from an increase of load capacity, the chief aim is to solve the complex problem of reducing the noise generation by load-conditioned kinematic modifications of the tooth mesh. In Part II, we shall deal with operating sequences and machining results and with gear noise problems.

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