Stress

GEAR TALK WITH CHUCK | 2019-10-08

So, Where Do I Start?

The last blog posting cautioned against over reliance on reference books for design guidance. A perfectly logical follow-up to that caution is “Whe...

TECHNICAL ARTICLES | 2019-09-01

A Precise Prediction of the Tooth Root Stresses for Involute External Gears with Any Fillet Geometry under Consideration of the Exact Meshing Condition

This paper shows a method to calculate the occurring tooth root stress for involute, external gears with any form of fillets very precisely within a few seconds.

GEAR TALK WITH CHUCK | 2019-08-13

Gear Origins: Roman Cisek

I was lucky to get a job as a design engineer – drive train department with a big construction equipment manufacturer (HSW) in Poland, right after ...

TECHNICAL ARTICLES | 2019-08-01

Impact of Root Geometry Manufacturing Deviations from a Theoretical Hob Rack on Gear Bending Stress

This study emphasizes the importance of a closed-loop approach togear design and manufacturing to assure designed root fillet shapes are attained in production, and gears meet the design intent.

GEAR TALK WITH CHUCK | 2019-07-11

Different Countries, Common Needs

Graham Penning’s career in gears began around the time mine did, the early 1970s, and although our paths have never crossed they are very similar. ...

GEAR TALK WITH CHUCK | 2019-07-05

Gear Origins: Graham Penning

For the last few years I have delivered a gear foundation course to both young and experienced engineers wanting to understand gear technology, and...

GEAR TALK WITH CHUCK | 2019-05-24

Finding the Limits

Jim Richard’s account of his journey from youthful experimenter to designer of cutting edge gear processing equipment illustrates the amazing thing...

GEAR TALK WITH CHUCK | 2019-05-02

A Fresh Set of Eyes

Hanspeter Dinner’s account of his “baptism by fire” into the gear industry contains a number of important lessons for other “newbies”; some reminde...

GEAR TALK WITH CHUCK | 2019-04-19

The Personal Touch

Our most recent guest blogger, Joe Arvin, demonstrates the importance of the personal touch in business. As I mentioned in my introduction to his s...

GEAR TALK WITH CHUCK | 2019-03-26

Remembering the Giants

While writing about the “degrees of connection” between current industry leaders and th...

GEAR TALK WITH CHUCK | 2018-11-06

Permanent Records

Avoiding corpo...

TECHNICAL ARTICLES | 2018-11-01

The Influence of a Grinding Notch on the Gear Bending Strength Rating

To achieve the requested quality, most gears today are ground. The usual grinding process includes treating the gear flank but disengaging before reaching the root rounding area. If the gear is premanufactured with a tool without protuberance, then at the position where the grinding tool retracts from the flank a grinding notch in the tooth root area is produced. Such a notch may increase the bending stresses in the root area, thus reducing the strength rating.

GEAR TALK WITH CHUCK | 2018-10-04

Repairing Gears

Deadlines and budgets do not always allow for “first class” gearbox rebuilds. The challenge for rebuild shops is to find the fastest and most econo...

GEAR TALK WITH CHUCK | 2018-10-02

Necessity as the Mother of Invention

When you offer rebuilding service...

GEAR TALK WITH CHUCK | 2018-09-27

Acceptable Fixes

You do not always have to say “no” when confronted with non-conforming parts. Here are a few “fixes” I have been comfortable authorizing:

GEAR TALK WITH CHUCK | 2018-08-02

Gearbox Specs: Connecting to the System

Your specifica...

TECHNICAL ARTICLES | 2018-08-01

Influences of the Residual Stress Condition on the Load-Carrying Capacity of Case-Hardened Gears

Highly loaded gears are usually casehardened to fulfill the high demands on the load-carrying capacity. Several factors, such as material, heat treatment, or macro and micro geometry, can influence the load-carrying capacity. Furthermore, the residual stress condition also significantly influences load-carrying capacity. The residual stress state results from heat treatment and can be further modified by manufacturing processes post heat treatment, e.g. grinding or shot peening.

GEAR TALK WITH CHUCK | 2018-06-14

Options for Material Selection

Disclaimer: This is the policy I follow for material selection. Your situation may call for a different decision. You should not adopt this pol...

GEAR TALK WITH CHUCK | 2018-06-07

Hardenability 102

Material Grade in Gears

GEAR TALK WITH CHUCK | 2018-05-18

Parametric Design

One of the scariest things a gear designer can face is a blank sheet of paper. This is why most of our products are “derivative” rather than “revol...

GEAR TALK WITH CHUCK | 2018-05-03

That X Factor

Our international readers are no doubt chuckling over this silly, American “long addendum” terminology. The “civilized world” has long relied on a ...

GEAR TALK WITH CHUCK | 2018-03-01

Out of Your Depth?

How did that over pin calculation work out? My congratulations if you managed to work your way through it without tearing your hair out. Guess what...

GEAR TALK WITH CHUCK | 2018-01-23

The First Step is Easy

When I started writing my gear book back in 1986, the mission was to provide enough information for a person new to the gear trade to tell if someo...

GEAR TALK WITH CHUCK | 2018-01-11

The Beginning of Wisdom

Faithful followers of this blog can complete that mantra without prompting, but for new readers — the beginning of wisdom is calling things by thei...

GEAR TALK WITH CHUCK | 2017-12-14

Engineering Safety (Part Two)

To an engineer there are no accidents, only unanticipated consequences of situations that need to be better understood. We even have a rule about i...

GEAR TALK WITH CHUCK | 2017-10-31

Gear Expo Swag Report

Soon you will be reading lots of stories about the 2017 AGMA Fall Technical Meeting and Gear Expo in our magazine and online reports. BUT, the info...

INDUSTRY NEWS | 2017-10-25

Gear Expo Day 1

GEAR TALK WITH CHUCK | 2017-09-14

Developing Resilience

For many years, “robust” was a popular business buzz word. The idea was to make certain your procedures and processes were “strong” enough to withs...

FEATURE ARTICLES | 2017-09-01

Gear Expo 2017 and ASM Heat Treat 2017 Booth Previews

The latest technology on display in Columbus, OH. October 24-26.

GEAR TALK WITH CHUCK | 2017-07-28

A New Quoting Model?

Anyone actually enjoy quoting? For such an important part of daily business the process of establishing prices to offer a customer seems universall...

GEAR TALK WITH CHUCK | 2017-05-11

Here There Be Dragons

On the AGMA Helical Gear Rating Committee we frequently deal with how to warn users away from potentially dangerous designs. Some years ago our won...

GEAR TALK WITH CHUCK | 2017-04-11

Why Things Break

I used to tease our maintenance staff that there were only two reasons a machine went down: it went down because we worked on it or because we did ...

GEAR TALK WITH CHUCK | 2016-12-15

Repair, Replace, or Rebuild?

I enjoy watching car auctions on cable television. Some of my enjoyment comes from the commen...

GEAR TALK WITH CHUCK | 2016-12-06

It’s a 24/7/52 World

This curmudgeon recently got a good lesson on how the Internet has changed the world. My adult children have been trying to get...

GEAR TALK WITH CHUCK | 2016-09-15

Important Travel Skills

A cable TV movie brought a chuckle here at the world headquarters for an opening scene of two soon-to-be-dead characters arguing over a road map. A...

TECHNICAL ARTICLES | 2016-07-01

Influence of Hobbing Tool Generating Scallops on Root Fillet Stress Concentrations

While designing gear and spline teeth, the root fillet area and the corresponding maximum tensile stress are primary design considerations for the gear designer. Root fillet tensile stress may be calculated using macro-geometry values such as module, minor diameter, effective fillet radius, face width, etc.

GEAR TALK WITH CHUCK | 2016-06-14

Daily Chores

A current project has reminded me just how difficult it is to pull cost estimates together. You would think that with business being slow due to th...

GEAR TALK WITH CHUCK | 2015-11-12

The Price Disconnect

Traditionally, cost estimating is the basis for pricing. I was very surprised the first time a mentor pointed out that the two are often quite disc...

GEAR TALK WITH CHUCK | 2015-06-04

Things We Don’t Know

Noted gear consultant and gear educator Ray Drago is fond of saying that a consultant’s best answers usually start with “it depends.” Those of you ...

GEAR TALK WITH CHUCK | 2015-05-26

Short Lived Gearbox Designs

“All memorable quotations referring to gearboxes involve expletives.” Peter Wright The author of Fo...

GEAR TALK WITH CHUCK | 2015-04-23

Standards of Excellence

Cadillac once proclaimed itself the “Standard of the World” and did its level best to back that claim up with high levels of product quality and cu...

GEAR TALK WITH CHUCK | 2015-03-19

Gear Milestones Needed

[starbox]The American Gear Manufacturers Association (www.agma.org) will be celebrating its centennial in 2016. In preparation for the big party, t...

ASK THE EXPERT | 2015-03-01

Measuring Residual Stress in Gears

I have heard that X-ray diffraction does not tell the whole story and that I should really run a fatigue test. I understand this may be the best way, but is there another method that gives a high degree of confidence in the residual stress measurement?

GEAR TALK WITH CHUCK | 2015-02-10

Uncertain Times

[starbox] While the news media is heralding improved job and income growth, people in gear manufacturing are worried about the security of their j...

GEAR TALK WITH CHUCK | 2015-01-29

Feedback and Comments

[starbox] We are starting our second year of this blog and are pleased that it was named one of the Top 50 Design and Development Blogs on the Int...

GEAR TALK WITH CHUCK | 2015-01-20

Questioning New Techniques

[starbox] In my last blog I mentioned the great analysis tools available to today’s gear engineers. On a current project, we are eagerly awaitin...

GEAR TALK WITH CHUCK | 2015-01-09

It’s All About Context

[starbox] I was one of those kids that loved reading the dictionary to learn new words, and that interest has continued into my golden years. Th...

GEAR TALK WITH CHUCK | 2014-12-11

The “Friendly Skies” Rely Upon Friendly Passengers

[starbox] I haven’t flown much this year, so it was with some apprehension that I booked two trips in a single week recently. My wife warned me ...

GEAR TALK WITH CHUCK | 2014-11-07

The Importance of Perseverance

GEAR TALK WITH CHUCK | 2014-08-07

Calmness Under Fire

So far, I expect my ideal “leader” to have commitment and vision. A third requirement is calmness under fire. While my life has been blessedly free...

FEATURE ARTICLES | 2014-08-01

IMTS 2014: This is Big

Here's everything you need to know about IMTS 2014, including an interview with Peter Eelman, AMT's VP of Exhibitions and Communications.

FEATURE ARTICLES | 2014-07-01

No Compromising on Quality at Allison Transmission

Gleason 350GMS helps put higher quality, more reliable gears into its next-generation TC10 automatic transmission.

TECHNICAL ARTICLES | 2014-07-01

Innovative Induction Hardening Process with Pre-heating for Improved Fatigue Performance of Gear Component

Contact fatigue and bending fatigue are two main failure modes of steel gears, while surface pitting and spalling are two common contact fatigue failures -- caused by alternating subsurface shear stresses from the contact load between two gear mates. And when a gear is in service under cyclic load, concentrated bending stresses exist at the root fillet -- the main driver of bending fatigue failures. Induction hardening is becoming an increasingly popular response to these problems, due to its process consistency, reduced energy consumption, clean environment and improved product quality -- but not without issues of its own (irregular residual stresses and bending fatigue). Thus a new approach is proposed here that flexibly controls the magnitude of residual stress in the regions of root fillet and tooth flank by pre-heating prior to induction hardening. Using an external spur gear made of AISI 4340 as an example, this new concept/process is demonstrated using finite element modeling and DANTE commercial software.

GEAR TALK WITH CHUCK | 2014-06-24

Learning from the Past, Looking to the Future

[starbox] There is a new commercial airing that shows flashbacks of a young girl enjoying a family road trip from the rear facing seat in their ...

INDUSTRY NEWS | 2014-05-01

Industry News

The complete Industry News section from the May 2014 issue of Gear Technology.

GEAR TALK WITH CHUCK | 2014-03-28

What Happened to FEA?

[starbox] Thinking back on my experiences on the Helical Gear Rating Committee, I am a bit shocked at what hasn’t happened. As AGMA 218 was bein...

GEAR TALK WITH CHUCK | 2014-03-26

Where Do Allowable Stresses Come From?

One of the most important aspects of a gear rating standard is the allowable stress charts. For spur and ...

GEAR TALK WITH CHUCK | 2014-03-19

Limited Opportunities for One-Trick Ponies

When you work as an engineer for smaller companies you get to wear a lot of hats.

GEAR TALK WITH CHUCK | 2014-02-28

Internships: How Does the Employer Benefit? Part II

[starbox] In my previous post I talked about the official ways an internship program benefited our company. Today I’d like to talk about a coupl...

FEATURE ARTICLES | 2013-08-01

Leading the Way in Lead Crown Correction and Inspection

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…

TECHNICAL ARTICLES | 2013-06-01

Tooth Root Optimization of Powder Metal Gears - Reducing Stress from Bending and Transient Loads

This paper will provide examples of stress levels from conventional root design using a hob and stress levels using an optimized root design that is now possible with PM manufacturing. The paper will also investigate how PM can reduce stresses in the root from transient loads generated by abusive driving.

INDUSTRY NEWS | 2013-05-01

GT Extras

What's new on the Gear Technology website this month? Videos from DMG Mori-Seiki, the latest e-mail newsletter and updates on upcoming events, including the Kapp-Niles Rocky Mountain Gear School.

TECHNICAL ARTICLES | 2013-03-01

Recent Inventions and Innovations in Induction Hardening of Gears and Gear-Like Components

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

PRODUCT NEWS | 2013-01-01

Product News

The complete Product News section from the January/February 2013 issue of Gear Technology.

TECHNICAL ARTICLES | 2012-03-01

Controlling Gear Distortion and Residual Stresses During Induction Hardening

Induction hardening is widely used in both the automotive and aerospace gear industries to minimize heat treat distortion and obtain favorable compressive residual stresses for improved fatigue performance. The heating process during induction hardening has a significant effect on the quality of the heat-treated parts. However, the quenching process often receives less attention even though it is equally important.

FEATURE ARTICLES | 2012-01-01

New Energy - Same Challenges

Uncertainty casts a shadow over future business opportunities for manufacturers serving the new energy markets.

TECHNICAL ARTICLES | 2012-01-01

Evaluation of Methods for Calculating Effects of Tip Relief on Transmission Error, Noise and Stress in Loaded Spur Gears

The connection between transmission error, noise and vibration during operation has long been established. Calculation methods have been developed to describe the influence so that it is possible to evaluate the relative effect of applying a specific modification at the design stage. These calculations enable the designer to minimize the excitation from the gear pair engagement at a specific load. This paper explains the theory behind transmission error and the reasoning behind the method of applying the modifications through mapping surface profiles and determining load sharing.

TECHNICAL ARTICLES | 2011-06-01

Analysis and Testing of Gears with Asymmetric Involute Tooth Form and Optimized Fillet Form for Potential Application in Helicopter Main Drives

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

TECHNICAL ARTICLES | 2011-06-01

Drive Line Analysis for Tooth Contact Optimization of High-Power Spiral Bevel Gears

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

PRODUCT NEWS | 2011-05-01

Dearborn Precision Puts Dual Purpose Zeiss CMM to the Task

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.

TECHNICAL ARTICLES | 2011-01-01

Point-Surface-Origin Macropitting Caused by Geometric Stress Concentration

Point-surface-origin (PSO) macropitting occurs at sites of geometric stress concentration (GSC) such as discontinuities in the gear tooth profile caused by micropitting, cusps at the intersection of the involute profile and the trochoidal root fillet, and at edges of prior tooth damage, such as tip-to-root interference. When the profile modifications in the form of tip relief, root relief, or both, are inadequate to compensate for deflection of the gear mesh, tip-to-root interference occurs. The interference can occur at either end of the path of contact, but the damage is usually more severe near the start-of-active-profile (SAP) of the driving gear.

TECHNICAL ARTICLES | 2010-08-01

Crowning Techniques in Aerospace Actuation Gearing

One of the most effective methods in solving the edge loading problem due to excess misalignment and deflection in aerospace actuation gearing is to localize tooth-bearing contact by crowning the teeth. Irrespective of the applied load, if the misalignment and/or deflection are large enough to cause the contact area to reduce to zero, the stress becomes large enough to cause failure. The edge loading could cause the teeth to break or pit, but too much crowning may also cause the teeth to pit due to concentrated loading. In this paper, a proposed method to localize the contact bearing area and calculate the contact stress with crowning is presented and demonstrated on some real-life examples in aerospace actuation systems.

EVENTS | 2010-06-01

Gear Applications All the Rage at Windpower 2010

Capitalizing on a burgeoning new technology where gears are of great import, the gear community gathered en masse at the American Wind Energy Association’s Windpower Expo 2010.

FEATURE ARTICLES | 2010-05-01

Your Tax Dollars at Work: U.S. Commerce Department, Your Boots on the Ground Overseas

Easily one of the central issues affecting U.S. manufacturing is what one might call the exports deficit—the inability of American companies to sell products to, for instance, Asian markets, developing countries and other ports of call—due to what they perceive to be unfair trade agreements and or policies.

TECHNICAL ARTICLES | 2010-05-01

Allowable Contact Stresses in Jacking Gear Units Used in the Offshore Industry

An offshore jack-up drilling rig is a barge upon which a drilling platform is placed. The barge has legs that can be lowered to the sea floor to support the rig. Then the barge can be “jacked up” out of the water, providing a stable work platform from which to drill for oil and gas. Jack-up drilling rigs were first introduced in the late 1950s. Rack-and- pinion-type jack-up units were introduced soon after that and have dominated the industry ever since.

FEATURE ARTICLES | 2009-09-01

Grinding Gears for Racing Transmissions

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

TECHNICAL ARTICLES | 2009-07-01

The Effect of Manufaturing Microgeometry Variations on the Load Distribution Factor and on Gear Contact and Root Stresses

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.

TECHNICAL ARTICLES | 2009-05-01

In-Situ Measurement of Stresses in Carburized Gears via Neutron Diffraction

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

TECHNICAL ARTICLES | 2009-03-01

Grinding Induced Changes in Residual Stresses of Carburized Gears

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

TECHNICAL ARTICLES | 2008-11-01

An Investigation of the Influence of Shaft Misalignment on Bending Stresses of Helical Gears with Lead Crown

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

INDUSTRY NEWS | 2008-05-01

Industry News

The complete Industry News section from the May 2008 issue of Gear Technology.

TECHNICAL ARTICLES | 2007-09-01

The New Freedoms: Bevel Blades

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

TECHNICAL ARTICLES | 2007-09-01

Tooth-Bending Effects in Plastic Spur Gears

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

TECHNICAL ARTICLES | 2007-08-01

True Bending Stress in Spur Gears

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

TECHNICAL ARTICLES | 2007-03-01

Asymmetric Teeth: Bending Stress Calculation

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

INDUSTRY NEWS | 2006-02-07

Induction Heating Companies Combine Sales Efforts

Inductoheat Inc., Radyne Corp., Newelco and HIS combined their sales efforts to serve induction heating and forging customers. Accord...

FEATURE ARTICLES | 2005-09-01

The Unofficial Guide to Gear Expo 2005

Booth Listings for Gear Expo 2005 in Detroit.

INDUSTRY NEWS | 2005-02-13

REM Chemicals and Rosler GmbH Partner in Metal Finishing

REM Chemicals Inc.and Rosler GmbH developed a 20-year global marketing partnership for chemically-accelerated mass finishing processes, m...

TECHNICAL ARTICLES | 2004-11-01

Non-Standard Cylindrical Gears

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

INDUSTRY NEWS | 2004-04-17

Manufacturing Association Elects New Board of Directors

The Association for Manufacturing Technology has its elected new officers at their 2004 conference in Bonita Springs, FL. David J. Bu...

TECHNICAL ARTICLES | 2003-09-01

Direct Gear Design: Bending Stress Minimization

Bending stress evaluation in modern gear design is generally based on the more-than-one-hundred-year-old Lewis equation.

TECHNICAL ARTICLES | 2003-03-01

Design Robustness and it Effect on Transmission Error and Other Design Parameters

Transmission errors, axial shuttling forces and friction result in bearing forces that serve as the major excitations of gear noise. This paper will use these factors as well as gear stresses and tribological factors to assist in obtaining optimal gear designs.

TECHNICAL ARTICLES | 2002-11-01

The Barkhausen Noise Inspection Method for Detecting Grinding Damage in Gears

When hardened steel components are ground, there is always the possibility of damage to the steel in the form of residual stress or microstructural changes. Methods for detecting this sort of damage have always had one or more drawbacks, such as cost, time, complexity, subjectivity, or the use of hazardous chemicals.

TECHNICAL ARTICLES | 2002-11-01

Predicting the Heat-Treat Response of a Carburized Helical Gear

Using the DANTE software, a finite element simulation was developed and executed to study the response of a carburized 5120 steel helical gear to quenching in molten salt. The computer simulation included heat-up, carburization, transfer and immersion in a molten salt bath, quenching, and air cooling. The results of the simulation included carbon distribution of phases, dimensional change, hardness, and residual stress throughout the process. The predicted results were compared against measured results for hardness, dimensions and residual stress. The excellent agreement between predictions and measured values for this carburized 5120 steel gear provides a basis for assessing the various process parameters and their respective importance in the characteristics of not only these heat-treated parts, but of other compositions and shapes.

TECHNICAL ARTICLES | 2002-05-01

Carbide Hobbing Case Study

Bodine Electric Co. of Chicago, IL., has a 97-year history of fine-and medium-pitch gear manufacturing. Like anywhere else, traditions, old systems, and structures can be beneficial, but they can also become paradigms and obstacles to further improvements. We were producing a high quality product, but our goal was to become more cost effective. Carbide hobbing is seen as a technological innovation capable of enabling a dramatic, rather than an incremental, enhancement to productivity and cost savings.

VOICES | 2002-01-01

The Gear Analysis Handbook by James L. Taylor Vibration Consultants Inc.

The author has written this book primarily from the viewpoint of analyzing vibrations on heavy industrial and mill gearing that may have been in service for a prolonged time. The purpose is to diagnose problems, especially the source or cause of failure. However, the principles and analysis techniques can be used for all types and sizes of gears, as well as for gear noise analysis.

TECHNICAL ARTICLES | 2001-05-01

Design Formulas for Evaluating Contact Stress in Generalized Gear Pairs

A very important parameter when designing a gear pair is the maximum surface contact stress that exists between two gear teeth in mesh, as it affects surface fatigue (namely, pitting and wear) along with gear mesh losses. A lot of attention has been targeted to the determination of the maximum contact stress between gear teeth in mesh, resulting in many "different" formulas. Moreover, each of those formulas is applicable to a particular class of gears (e.g., hypoid, worm, spiroid, spiral bevel, or cylindrical - spur and helical). More recently, FEM (the finite element method) has been introduced to evaluate the contact stress between gear teeth. Presented below is a single methodology for evaluating the maximum contact stress that exists between gear teeth in mesh. The approach is independent of the gear tooth geometry (involute or cycloid) and valid for any gear type (i.e., hypoid, worm, spiroid, bevel and cylindrical).

INDUSTRY NEWS | 2001-01-01

Industry News

Complete Industry News for January/February 2001.

PUBLISHER'S PAGE | 2000-11-01

A Pause That Refreshes

When you to to IMTS, you expect to see hoopla. The mass of machines and bodies gathered in one place should create an unmistakable level of energy and enthusiasm. IMTS 2000 seemed uncharacteristically quiet...

INDUSTRY NEWS | 2000-07-01

Determining Lead Error on a Crowned Pinion

Q&A is your interactive gear forum.

REVOLUTIONS | 1999-07-01

Revolutions

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

INDUSTRY NEWS | 1998-11-01

Changes In The Gear Industry

Industry News for November/December 1998.

TECHNICAL ARTICLES | 1998-09-01

Comparing Standards

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.

TECHNICAL ARTICLES | 1998-01-01

Influence of Gear Design on Gearbox Radiated Noise

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

TECHNICAL ARTICLES | 1997-07-01

Basic Honing & Advanced Free-Form Honing

Rotary gear honing is a crossed-axis, fine, hard finishing process that uses pressure and abrasive honing tools to remove material along the tooth flanks in order to improve the surface finish (.1-.3 um or 4-12u"Ra), to remove nicks and burrs and to change or correct the tooth geometry. Ultimately, the end results are quieter, stronger and longer lasting gears.

FEATURE ARTICLES | 1997-03-01

Induction Heat Trating: Things Remembered, Things Forgotten

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.

TECHNICAL ARTICLES | 1996-11-01

The Advantages of Ion Nitriding Gears

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

TECHNICAL ARTICLES | 1996-03-01

Wear Protection for Gears

Several trends in mechanical engineering are leading to greater surface stress on components and thus to unacceptable wear. These trends include greater stresses due to increased power densities; the need to maintain high precision of components throughout their service life; and the environmental imperative to reduce use of lubricants and additives.

TECHNICAL ARTICLES | 1993-05-01

Practical Optimization of Helical Gears Using Computer Software

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

TECHNICAL ARTICLES | 1992-07-01

Comparing Surface Failure Modes in Bearings and Gears: Appearances vs. Mechanisms

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.

MANAGEMENT MATTERS | 1992-05-01

Cost-Cutting ABCs

Cost cutting. It's the aerobics of the 90s for businesses large and small. More than just the latest buzzword or 90-second flash-in-the-panacea, it's a survival technique. Companies that aren't trimming the fat now may not be around in five years to regret that they didn't.

INDUSTRY NEWS | 1992-03-01

Our Experts Discuss Hobbing Ridges, Crooked Gear Teeth, and Crown Shaving

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

PUBLISHER'S PAGE | 1990-03-01

Capital Gains, Societal Gains, or No Gains At All

Taxes may be one of the only two sure things in life, but that doesn't make them popular. Nobody is happy to pay them, and the bigger the amount due, the unhappier the taxpayer. Conversely, politicians know that coming out in favor of a tax cut is the equivalent of voting for apple pie and motherhood. It's a sure-fire success at the ballot box.

TECHNICAL ARTICLES | 1988-05-01

Tooth Root Stresses of Spiral Bevel Gears

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

VOICES | 1987-07-01

No Surprise

For the last few years, the market has been tough for the U.S. gear industry. That statement will cause no one any surprise. The debate is about what to do. One sure sign of this is the enormous attention Congress and the federal government are now placing on "competitiveness."

PUBLISHER'S PAGE | 1987-01-01

Industry Shows Shift Emphasis

A change has taken place within the industry that is going to have an enormous effect on the marketing, sales, and purchasing of gear manufacturing and related equipment. This change was the American Gear Manufacturers' Association, first biennial combination technical conference and machine tool minishow.

TECHNICAL ARTICLES | 1986-03-01

CNC Gear Shaping

Two major processes used for cutting gears, hobbing and shaping. This article describes advanced machine design and cutter materials for gear shaping.

INDUSTRY NEWS | 1986-01-01

The Process of Gear Shaving

Gear shaving is a free-cutting gear finishing operation which removes small amounts of metal from the working surfaces of the gear teeth. Its purpose is to correct errors in index, helical angle, tooth profile and eccentricity. The process can also improve tooth surface finish and eliminate, by crowned tooth forms, the danger of tooth end load concentrations in service. Shaving provides for form modifications that reduce gear noise. These modifications can also increase the gear's load carrying capacity, its factor of safety and its service life.

TECHNICAL ARTICLES | 1985-07-01

Influence of Relative Displacements Between Pinion and Gear on Tooth Root Stresses of Spiral Bevel Gears

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

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.