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Articles About gearbox inspection


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1 Turbine Gearbox Inspection - Steady Work in a Shaky Wind Market (August 2013)

Having outlasted the worldwide Great Recession, the Global Wind Energy Council (GWEC) forecasts a constant growth in wind energy, i.e.: "increase in worldwide capacity to 460,000 MW by 2015."

2 How to Inspect a Gearbox (September 2013)

Although a comprehensive on-site gearbox inspection is desirable in many situations, there may be constraints that limit the extent of the inspection such as cost, time, accessibility and qualified personnel. This article describes the equipment and techniques necessary to perform an on-site gearbox inspection.

3 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.

4 Improving Gear Manufacturing Quality With Surface Texture Measurement (March/April 1993)

The working surfaces of gear teeth are often the result of several machining operations. The surface texture imparted by the manufacturing process affects many of the gear's functional characteristics. To ensure proper operation of the final assembly, a gear's surface texture characteristics, such as waviness and roughness, can be evaluated with modern metrology instruments.

5 Little Things Mean A Lot (March/April 1993)

"God is in the details," says the philosopher. What he meant was that on the scale of the universe, it's not just the galaxies, the planets, the mountain ranges, or the major rivers that are important. So are the subatomic particles and the genes. It's the little things that make all the difference.

6 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.

7 Gear Inspection and Measurement (July/August 1992)

The purpose of gear inspection is to: Assure required accuracy and quality, Lower overall cost of manufacture by controlling rejects and scrap, Control machines and machining practices and maintain produced accuracy as machines and tools wear, Determine hear treat distortions to make necessary corrections.

8 Effects of Temperature on Gage Repeatability & Reproducibility (May/June 1992)

Temperature Induced Dimensional Changes Temperature causes various materials to change size at different rate, known as their Coefficients of Expansion (COE). The effects of this phenomenon on precision dimensional measurements are continuous and costly to industry. Precautions can be taken to allow parts and gages to temperature stabilize before conducting gage R & R studies, but the fact remains that on the shop floor temperatures vary all the time. The slow pace at which industry has accepted this reality probably has to do with the subtlety of these tiny size variations and our inability to sense gradual, but significant temperature changes.

9 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.

10 A Comparison of ISO 4156-ANSI B92.2M - 1980 With Older Imperial Standards (September/October 1994)

The purpose of this article is to discuss ISO 4156/ANSI B92.2M-1980 and to compare it with other, older standards still in use. In our experience designing and manufacturing spline gauges and other spline measuring or holding devices for splined component manufacturers throughout the world, we are constantly surprised that so many standards have been produced covering what is quite a small subject. Many of the standards are international standards; others are company standards, which are usually based on international standards. Almost all have similarities; that is, they all deal with splines that have involute flanks of 30 degrees, 37.5 degrees or 45 degrees pressure angle and are for the most part flank-fitting or occasionally major-diameter-fitting.

11 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.

12 Gear Inspection For The Long Haul (September/October 1995)

Question: We just received permission to purchase our first CNC gear inspection system. With capital approvals so hard to come by, especially for inspection equipment, I want to be sure to purchase a system I can count of for years to come. My past experience with purchasing CNC equipment has shown me that serviceability of the computer and the CNC controller portion of the system can be a problem in just a few years because of the obsolescence factor. What information do I need to look for when selecting a supplier to reduce the risk of obsolescence, as well as to reduce the long-term servicing costs in the computer and controls portion of the system?

13 Quality Gear Inspection - Part II (November/December 1994)

This section will deal with the use of gear inspection for diagnostic purposes rather than quality determination. The proper evaluation of various characteristics in the data can be useful for the solution of quality problems. It is important to sort out whether the problem is coming from the machine, tooling and/or cutters, blanks, etc. An article by Robert Moderow in the May/June 1985 issue of Gear Technology is very useful for this purpose.

14 Quality Gear Inspection - Part I (September/October 1994)

Quality gear inspection means doing the "right" inspections "right." A lot of time and money can be spent doing the wrong types of inspections related to function and doing them incorrectly. As we will discover later, such things as runout can creep into the manufacturing and inspection process and completely ruin any piece of data that is taken. this is one of the most important problems to control for quality inspection.

15 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?

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 Recent Developments in Gear Metrology (November/December 1991)

Metrology is a vital component of gear manufacturing. Recent changes in this area, due in large part to the advent of computers, are highlighted in this article by comparison with more traditional methods.

18 Tomorrow's Gear Inspection Systems: Arriving Just in Time (June/July 2012)

Gleason's GMS analytical gear inspection systems provide all the right features at Eaton Corp.

19 Gear Quality Inspection: How Good is Yours (June/July 2012)

How well you conduct your inspections can be the difference-maker for securing high-value contracts from your customers. And as with most other segments of the gear industry, inspection continues striving to attain “exact science” status. With that thought in mind, following is a look at the state of gear inspection and what rigorous inspection practices deliver—quality.

20 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.

21 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.

22 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.

23 Runout, Helix Accuracy and Shaper Cutters (June/July 2012)

Our experts discuss runout and helix accuracy, as well as the maximum number of teeth in a shaper cutter.

24 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.

25 Single Flank Measuring; Estimating Horsepower Capacity (September/October 1991)

Question: What is functional measurement and what is the best method for getting truthful answers?

26 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.

27 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.

28 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.

29 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.

30 Viewpoint (November/December 1991)

Dear Editor: In Mr. Yefim Kotlyar's article "Reverse Engineering" in the July/August issue, I found an error in the formula used to calculate the ACL = Actual lead from the ASL = Assumed lead.

31 Rebuilding a Metrology Infrastructure (January/February 1996)

The American Society of Mechanical Engineers (ASME) announced at Gear Expo '95 that a national service for the calibration of involute artifacts is now available at the Department of Energy's Y-12 Plant in Oak Ridge, TN.

32 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.

33 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.

34 Leading the Way in Lead Crown Correction and Inspection (August 2013)

Forest City Gear applies advanced gear shaping and inspection technologies to help solve difficult lead crown correction challenges half a world away. But these solutions can also benefit customers much closer to home, the company says. Here's how…

35 Liebherr Touts Technology at Latest Gear Seminar (June/July 2013)

For two days in Saline, Michigan, Liebherr's clients, customers and friends came together to discuss the latest gear products and technology. Peter Wiedemann, president of Liebherr Gear Technology Inc., along with Dr.-Ing. Alois Mundt, managing director, Dr.-Ing. Oliver Winkel, head of application technology, and Dr.-Ing. Andreas Mehr, technology development shaping and grinding, hosted a variety of informative presentations.

36 CMM Gear Inspection (January/February 2013)

Mitutoyo offers capable, affordable and flexible gear inspection option via coordinate measuring machines and gear inspection software.

37 Measurement of Involute Master (January/February 2013)

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

38 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.

39 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.

40 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.

41 Portable Gear Inspection (July 2014)

Compact, custom and portable solutions are gaining more attention in manufacturing today as companies seek out the tools that offer the greatest productivity gains on the shop floor. Gear inspection seems to be following suit.

42 Practical Considerations for the Use of Double-Flank Testing for the Manufacturing Control of Gearing - Part II (March/April 2014)

Part I of this paper, which appeared in the January/February issue of Gear Technology, described the theory behind double-flank composite inspection. It detailed the apparatus used, the various measurements that can be achieved using it, the calculations involved and their interpretation. The concluding Part II presents a discussion of the practical application of double-flank composite inspection -- especially for large-volume operations. It also addresses 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.

43 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.

44 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.

45 IMTS 2012 Product Preview (September 2012)

Previews of manufacturing technology related to gears that will be on display at IMTS 2012.

46 The Basics of Gear Metrology and Terminology Part II (November/December 1998)

In the last section, we discussed gear inspection; the types of errors found by single and double flank composite and analytical tests; involute geometry; the involute cam and the causes and symptoms of profile errors. In this section, we go into tooth alignment and line of contact issues including lead, helix angles, pitch, pitchline runout, testing and errors in pitch and alignment.

47 M & M Precision, Penn State & NIST Team Up For Gear Metrology Research (July/August 1997)

In 1993, M & M Precision Systems was awarded a three-year, partial grant from the Advanced Technology Program of the Department of Commerce's National Institute of Standards and Technology (NIST). Working with Pennsylvania State University, M&M embarked on a technology development project to advance gear measurement capabilities to levels of accuracy never before achieved.

48 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.

49 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.

50 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.

51 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.

52 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%.

53 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.

54 Programmable Separation of Runout From Profile and Lead Inspection Data for Gear Teeth With Arbitrary Modifications (March/April 1998)

A programmable algorithm is developed to separate out the effect of eccentricity (radial runout) from elemental gear inspection date, namely, profile and lead data. This algorithm can be coded in gear inspection software to detect the existence, the magnitude and the orientation of the eccentricity without making a separate runout check. A real example shows this algorithm produces good results.

55 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.

56 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.

57 Automated Inspection Systems: The Whole Picture (January/February 1998)

No one (not even you and I) consistently makes parts with perfect form and dimensions, so we must be able to efficiently check size and shape at many stages in the manufacturing and assembly process to eliminate scrap and rework and improve processes and profits. Automated inspection systems, which are widely used in all kinds of manufacturing operations, provide great efficiencies in checking individual features, but may not be as effective when asked to evaluate an entire part. You need to know why this is true and what you can do to improve your part yields.

58 Thermal Effects on CMMs (September/October 1997)

The trend toward moving coordinate measuring machines to the shop floor to become an integral part of the manufacturing operations brings real time process control within the reach of many companies. Putting measuring machines on the shop floor, however, subjects them to harsh environmental conditions. Like any measuring system, CMMs are sensitive to any ambient condition that deviates from the "perfect" conditions of the metrology lab.

59 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.

60 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.

61 Gear Transmission Density Maximization (November/December 2011)

This paper presents an approach that provides optimization of both gearbox kinematic arrangement and gear tooth geometry to achieve a high-density gear transmission. It introduces dimensionless gearbox volume functions that can be minimized by the internal gear ratio optimization. Different gearbox arrangements are analyzed to define a minimum of the volume functions. Application of asymmetric gear tooth profiles for power density maximization is also considered.

62 It's No American Dream: Pratt & Whitney GTF Engine Now a Reality... (November/December 2011)

In the August 2008 issue of Gear Technology, we ran a story (“Gearbox Speed Reducer Helps Fan Technology for ‘Greener” Jet Fuel Efficiency’) on the then ongoing, extremely challenging and protracted development of Pratt & Whitney’s geared turbofan (GTF) jet engine.

63 Comparison of Test Rig and Field Measurement Results on Gearboxes for Wind Turbines (October 2011)

This article describes some of the most important tests for prototypes conducted at Winergy AG during the product development process. It will demonstrate that the measurement results on the test rig for load distribution are in accordance with the turbine measurements.

64 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.

65 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.

66 Full-Load Testing of Large Gearboxes Using Closed-Loop Power Circulation (September/October 1991)

This method of testing large gearboxes or, indeed, any power transmission element, had numerous advantages and offers the possibility of large savings in time, energy, and plant, if the overall situation is conducive to its use. This usually requires that several such units need to be tested, and that they can be conveniently connected to each to each other in such a way as to form a closed-loop drive train. No power sink is required, and the drive input system has only to make up power losses. The level of circulating power is controlled by the torque, which is applied statically during rotation, and the drive speed. Principles, advantage, and limitations are described, together with recent experiences in the only known large-scale usage of this technique in Australia.

67 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?

68 Romax Technology Launches Gearbox and Driveline Design Software Package (November/December 2012)

Romax Technology, the gearbox, bearing and driveline engineering specialist, has launched a new design software package that will increase speed, quality, creativity and innovation when designing gearboxes and drivelines. Called Concept, the new product delivers on the Romax vision of streamlining the end-to-end, planning-to-manufacture process with open, easy to use software solutions. It has been developed in close collaboration with engineers in the largest ground vehicle, wind energy and industrial equipment companies around the globe.

69 Understanding Oil Analysis: How it Can Improve Reliability of Wind Turbine Gearboxes (November/December 2013)

Historically, wind turbine gearbox failures have plagued the industry. Yet an effective oil analysis program will increase the reliability and availability of your machinery, while minimizing maintenance costs associated with oil change-outs, labor, repairs and downtime. Practical action steps are presented here to improve reliability.

70 How Bearing Design Improves Gearbox Performance (September 2012)

Gearbox performance, reliability, total cost of ownership (energy cost), overall impact on the environment, and anticipation of additional future regulations are top-of-mind issues in the industry. Optimization of the bearing set can significantly improve gearbox performance.

71 New Guidelines For Wind Turbine Gearboxes (May/June 1998)

The wind turbine industry has been plagued with gearbox failures, which cause repair costs, legal expenses, lost energy production and environmental pollution.

72 Developing a Total Productive Maintenance System (May/June 1995)

There's a reason they call it catastrophic gear failure: For example, if the line goes down at a large aluminum rolling mill because a gear set goes bad, the cost can run up to a whopping $200,000 a week. Even in smaller operations, the numbers alone (not to mention all the other problems) can be a plant manager's worst nightmare.

73 Wind Standard Closer to Completion (March/April 2011)

Faithful Gear Technology readers may recall that our July 2009 issue contained an update of the deliberations provided by Bill Bradley. Now, almost two years later, there is an ISO/IEC wind turbine gearbox standard out for draft international standard ballot (ballot closes 2011-05-17).

74 Engagement of Metal Debris into Gear Mesh (September/October 2010)

A series of bench-top experiments was conducted to determine the effects of metallic debris being dragged through meshing gear teeth. A test rig that is typically used to conduct contact fatigue experiments was used for these tests. Several sizes of drill material, shim stock and pieces of gear teeth were introduced and then driven through the meshing region. The level of torque required to drive the “chip” through the gear mesh was measured. From the data gathered, chip size sufficient to jam the mechanism can be determined.

75 An International Wind Turbine Gearbox Standard (July 2009)

Industrial gear standards have been used to support reliability through the specification of requirements for design, manufacturing and verification. The consensus development of an international wind turbine gearbox standard is an example where gear products can be used in reliable mechanical systems today. This has been achieved through progressive changes in gear technology, gear design methods and the continual development and refinement of gearbox standards.

76 Understanding the Application: A Key to Economical Gearbox Purchases (November/December 2004)

On a highway, a compact pick-up truck struggles to tow a 30-foot boat up a steep grade. Inside the pick-up, the owner curses himself. He saved money leasing a smaller truck but sees now that he really needed a bigger, pricier vehicle, one suitable for this job.

77 Understanding Fluid Flow to Improve Lubrication Efficiency (January/February 2004)

Excess lubricant supply in gearing contributes to power loss due to churning as well as the requirements of the lubrication system itself. Normally, a much larger amount of oil than required is used for cooling because so much of it is thrown away by centrifugal force. To lower the amount of lubricant required and reduce those losses, it is necessary to discover the ideal location of the supplying nozzle.

78 A Whodunnit in Gearbox Failure (November/December 2008)

Forensics isn't just for tough-talking, crime-busting scientists--most commonly found on your television; the tactic also holds the key to successful gearbox design and manufacture.

79 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.

80 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.

81 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.

82 Wind Turbine Pitch and Yaw Drive Manufacturers Draw Breath as Market Slows (January/February 2010)

The global wind energy market has seen average growth rates of 28 percent over the last 10 years, according to the Global Wind Energy Council (GWEC), creating major challenges for the component supply industry. GWEC also forecasts an average growth rate of 22 percent for the next five years, which if realized, will continue to put pressure on suppliers of turbine components.

83 Tapping into the Wind Gearbox Supply Chain (January/February 2010)

Although typically considered a late bloomer in the call to wind energy arms, the United States is now the number one wind power producer in the world with over 25,000 MW installed by the end of 2008, according to the Global Wind Energy Council in January 2009.

84 Gearbox Speed Reducer Helps Fan Technology for "Greener" Jet Fuel Efficiency (August 2008)

Today’s ever-evolving global economic engine is, in many ways, a wonderful phenomenon; you know—a rising-tide-lifting-all-boats, trickle-down-theory-of-economics dynamic at work.

85 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.

86 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.

87 Better Gears & Splines With Metrology (July 2007)

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

88 Single Flank Data Analysis and Interpretation (September/October 1985)

Much of the information in this article has been extracted from an AGMA Technical Paper, "What Single Flank Testing Can Do For You", presented in 1984 by the author

89 Cotta Transmission Installs CMM with Gear Checking Module (July 2010)

Xspect Solutions Provides Wenzel Bridge-Type CMM Equipped with OpenDMIS Software for Basic Gear Measuring Capability with CMM Flexibility.

90 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.

91 User-Friendly Gear Measurement (July 2010)

Good timing leads to partnership between Process Equipment and Schafer Gear.

92 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.

93 Improved Inspection Software Helps Provide Optimum Cutting Results (July 2010)

Klingelnberg measuring centers eliminate trial-and-error with modern analysis tools.

94 Zoller and Ingersoll Partner for Measuring Hob Cutters (March/April 2011)

With growing markets in aerospace and energy technologies, measuring hob cutters used in gear cutting is becoming an essential requirement for workpieces and machine tools. Zoller, a provider of solutions for tool pre-setters, measuring and inspection machines and tool management software, has developed a new partnership with Ingersoll/Germany for shop floor checking of hob cutters by a combined hardware and software approach.

95 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.

96 Not All Good Ideas Are Brand New (September 2011)

A reader clarifies technology presented in the March/April 2011 issue.

97 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.

98 Benefit of Psychoachoustic Analyzing Methods for Gear Noise Investigation (August 2011)

This article provides an overview of the benefits of using psychoacoustic characteristics for describing gear noise. And with that, human hearing and the most important psychoacoustic values are introduced. Finally, results of noise tests with different gear sets aree presented. The tests are the basis for a correlation analysis between psychoacoustic values and gear characteristics.

99 An Emphasis on Accuracy (June/July 2011)

Meeting the many challenges of large gear inspection.

100 Dearborn Precision Puts Dual Purpose Zeiss CMM to the Task (May 2011)

When parts you manufacture pass through numerous processes such as deep hole drilling, machining, hobbing and grinding, a CMM is essential when your customers require 100 percent in-process and final inspection.

101 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.

102 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.

103 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.

104 Gear Inspection and Chart Interpretation (May/June 1985)

Much information has been written on gear inspection, analytical. functional. semiautomatic and automatic. In most cases, the charts, (if you are lucky enough to have recording equipment) have been explained.

105 Revolutions (May/June 2004)

"Frenco--Inspecting All Flanks in Minutes."

106 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.

107 Industry Forum (September/October 1985)

Your May/June issue contains a letter from Edward Ubert of Rockwell International with some serious questions about specifying and measuring tooth thickness.

108 Practical Magic - Metrology Products Keep Pace with Machine Technology (July 2009)

Gear metrology is a revolving door of software packages and system upgrades. It has to be in order to keep up with the productivity and development processes of the machines on the manufacturing floor. Temperature compensation, faster inspection times and improved software packages are just a few of the advancements currently in play as companies prepare for new opportunities in areas like alternative energy, automotive and aerospace/defense.

109 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.

110 Calibration of Two-Flank Roll Testers (May 2008)

The presence of significant errors in the two-flank roll test (a work gear rolled in tight mesh against a master gear) is well-known, but generally overlooked.

111 Update on the National Center for Gear Metrology (May 2008)

The status on traceability of gear artifacts in the United States.

112 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.

113 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.

114 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.

115 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.