Backlash

ASK THE EXPERT | 2016-08-01

Helical Gear Systems

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?

TECHNICAL ARTICLES | 2016-06-01

Worm Gear Efficiency Estimation and Optimization

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

TECHNICAL ARTICLES | 2016-06-01

Gear Backlash Analysis of Unloaded Gear Pairs in Transmissions

A best practice in gear design is to limit the amount of backlash to a minimum value needed to accommodate manufacturing tolerances, misalignments, and deflections, in order to prevent the non-driving side of the teeth to make contact and rattle. Industry standards, such as ANSI/AGMA 2002 and DIN3967, provide reference values of minimum backlash to be used in the gear design. However, increased customers' expectations in vehicle noise eduction have pushed backlash and allowable manufacturing tolerances to even lower limits. This is especially true in the truck market, where engines are quieter because they run at lower speeds to improve fuel economy, but they quite often run at high torsional vibration levels. Furthermore, gear and shaft arrangements in truck transmissions have become more complex due to increased number of speeds and to improve efficiency. Determining the minimum amount of backlash is quite a challenge. This paper presents an investigation of minimum backlash values of helical gear teeth applied to a light-duty pickup truck transmission. An analytical model was developed to calculate backlash limits of each gear pair when not transmitting load, and thus susceptible to generate rattle noise, through different transmission power paths. A statistical approach (Monte Carlo) was used since a significant number of factors affect backlash, such as tooth thickness variation; center distance variation; lead; runout and pitch variations; bearing clearances; spline clearances; and shaft deflections and misalignments. Analytical results identified the critical gear pair, and power path, which was confirmed experimentally on a transmission. The approach presented in this paper can be useful to design gear pairs with a minimum amount of backlash, to prevent double flank contact and to help reduce rattle noise to lowest levels.

GEAR TALK WITH CHUCK | 2016-02-09

Discovering Gears

Recently, an attorney told me that his eleven-year-old daughter had “discovered” gears in a science class and was excitedly learning all she could ...

ASK THE EXPERT | 2016-01-01

Premature Gear Failure

I would appreciate if you could assist with a gear failure (occurring) after just seven weeks in service, post installation. This driving gear wheel has been installed in a medium-speed engine with backlash present at four different positions; with additional backlash checked on the mating surfaces. All backlash was found within (OEM)-recommended values. Please note included photos - it seems that the crack has started at the root fillet. Any comments would be appreciated.

INDUSTRY NEWS | 2015-08-21

Suhner Spiral Bevel Gears Offer High Power, Low Backlash and Low Noise

Each year, increased engine and motor power require more powerful angle gear heads. Engineers in the tool-making and industrial hand too...

ASK THE EXPERT | 2015-06-01

Gear mesh, NVH Evaluation

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.

ADDENDUM | 2015-05-01

Henry Maudslay

Here is some history that bears repeating - or at least re-reading. So take a few minutes to give it up for a long-gone Brit named Henry Maudslay (August 22, 1771 - February 14, 1831) - also known as "A Founding Father of Machine Tool Technology." You might also consider him an early leader in inspection, as he also invented the first bench micrometer capable of measuring to one ten-thousandth of an inch.

GEAR TALK WITH CHUCK | 2014-10-07

Spamsters be Damned — We're Bloggin' Here

[starbox] The anticipated, two-way dialog for this blog has been hampered by persistent spammers trying to scam their way onto t...

ASK THE EXPERT | 2014-06-01

Measuring Backlash in Bevel and Hypoid Gears

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

TECHNICAL ARTICLES | 2014-01-01

Practical Considerations for the Use of Double-Flank Testing for the Manufacturing Control of Gearing - Part I

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.

TECHNICAL ARTICLES | 2013-06-01

How to Design and Install Bevel Gears for Optimum Performance - Lessons Learned

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.

TECHNICAL ARTICLES | 2012-09-01

Refurbishing a Ball Mill ; Bevel Gear Backlash

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

EVENTS | 2010-11-01

Technically Speaking, a Huge Success

A recap of the AGMA 2010 Fall Technical Meeting.

INDUSTRY NEWS | 2006-03-10

Sterling Instrument’s Anti-Backlash Gears Eliminate Marred Shafts

A new series of 1158 anti-backlash gears manufactured by Sterling Instruments feature the Fairloc integral hub fastening system, which el...

PRODUCT NEWS | 2006-03-01

Shorter Cycle Times for Carburizing

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.

FEATURE ARTICLES | 2006-03-01

Blue Skies for Aerospace Parts Manufacturing

Aerospace manufacturing has seen quite a turnaround in the past few years. The world's manufacturers of airplanes, helicopters, missiles, space vehicles and satellites are all extremely busy right now--and that's keeping quite a few gear manufacturers busy as well.

INDUSTRY NEWS | 2005-04-16

Frenco Adds Gage for Measuring Splines to Produce A Circumferential Backlash Measuring Instrument

Frenco has expanded its product line by starting to produce a circumferential backlash measuring instrument. According to its press r...

VOICES | 1998-03-01

Viewpoint

Jules Kish responds to comments about his article on finding a hunting ratio, and Dr. Sante Basili argues that shaving is still the best way to finish a rough-cut gear.

TECHNICAL ARTICLES | 1996-05-01

Generating Precision Spur Gears By Wire EDM

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.

TECHNICAL ARTICLES | 1995-11-01

Determining Spline Misalignment Capabilities

Introducing backlash into spline couplings has been common practice in order to provide for component eccentric and angular misalignment. The method presented here is believed to be exact for splines with even numbers of teeth and approximate for those with odd numbers of teeth. This method is based on the reduction of the maximum effective tooth thickness to achieve the necessary clearance. Other methods, such as tooth crowning, are also effective.

ADDENDUM | 1995-03-01

The Second Edition...

Gearing for Munchkins Gene Kasten, president of Repair Parts, Inc., of Rockford, IL, is the proud owner of a miniature Barber-Colman hobber, the only one of its kind in the world. The machine, a replica of the old B-C "A" machine, was built between 1933 and 1941 by W. W. Dickover, who devoted 2, 640 hours of his spare time to the project.

INDUSTRY NEWS | 1994-09-01

Our Experts Discuss Electronic Gearboxes, Plus Backlash and What to Do about it

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?

TECHNICAL ARTICLES | 1994-05-01

Minimizing Backlash in Spur Gears

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.

TECHNICAL ARTICLES | 1992-01-01

Design Guidelines for High-Capacity Bevel Gear Systems

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

EVENTS | 1992-01-01

Calendar

Complete calendar for January/February 1992

TECHNICAL ARTICLES | 1987-09-01

The Interrelationship of Tooth Thickness Measurements as Evaluated by Various Measuring Techniques

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.

TECHNICAL ARTICLES | 1984-10-01

Endurance Limit for Contact Stress in Gears

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.

VOICES | 1984-08-01

A Second Rate Society - Never

What was once recognized as the unique genius of America is now slipping away from us and, in many areas, is now seen as a "second rate" capability. Unless action is taken now, this country is in real danger of being unable to regain its supremacy in technological development and economic vigor. First Americans must understand the serious implications of the problem; and second, we must dedicate ourselves to national and local actions that will ensure a greater scientific and technological literacy in America.