News & Events

gri-newsletter-headerVol. 26, 2021


As I look out my patio door and see the leaves falling from the trees, farmers harvesting the crops, butterflies flying around and the grass growing, one would never have thought anything is different from prior years.  But things are different aren’t they?  Instead of dwelling on recent events and all the changes they have brought about, I have chosen to dwell on the future.  Taking a snippet from JFK’s inaugural address, “Ask not what your country can do for you – ask what you can do for your country”, I am inspired to look beyond the problems of the last 18 months, but forward into the coming months.  

So you may be asking yourself, “Who is this new President and what can he do for GRI?”  Let me introduce myself; I’m Chad Behrman: a dad, husband, son, brother, friend, co-worker, helper and most of all a gearhead.  I got my BS in Mechanical Engineering from the University of Missouri back in 1995.  While going to college, I worked with cooling towers at Marley Cooling Towers in Kansas City.  My first job post-college was at York International in Wichita as a Manufacturing Engineer in the coil fabrication department, manufacturing evaporating and condensing coils for residential and commercial applications.  While in Kansas, I found my beautiful and wonderful bride, Lori, and then moved to Columbus, Indiana, to work for Diamet Corporation as a Product Engineer manufacturing automotive powder metal components.  After a few years, I moved over to Rolls-Royce Corporation in Indianapolis as a Design Engineer, working with transmissions and structures for gas turbine engines.  This past year I have celebrated being married for over 24 years and being with Roll-Royce for 20 years.  I’m also nearing the half century mark, and everyone is telling me that it’s all downhill after that!!

Of course all work and no play makes Chad a dull boy.  I do stay pretty active between church activities, keeping things running around the house and farm, drag racing my 66 Chevelle, and helping others out.  Truthfully, I’m not sure how I find time to actually do work.  But I love to design and improve things, whether that’s a gear contact pattern on a set of bevel gears, organizing electronic data so that it’s more easily accessible, or tweaking out that next tenth of a second out of the race car.

With respect to GRI, I would like to thank all of the prior and current leaders. They have done an outstanding job of providing a very solid foundation by which to build upon.  Over the years, GRI has strived to provide testing and resources that would be beneficial to various industries with respect to gear testing, measurement, inspection and analysis.  Improvements in measurement and detection capabilities have continually occurred, and new rig designs and methodologies have been created to allow for a wider range of testing capabilities.  Along with all of that has been an increasing desire from the industry to restart the GRI Vehicle Bloc to conduct pre-competitive, cooperative research focusing on automotive/off highway gear technologies.  As a result, GRI will be holding a virtual meeting to discuss the possibility of restarting a Vehicle Bloc group, which is discussed in more details below.  I would highly encourage anyone that is interested to take a moment to read the details below and to respond accordingly.

Thank you all for being a part of GRI and allowing me to help lead us into the future. 

God Bless,

Chad Behrman
President of the Board, GRI

chad behrman

Research Project: Bulk Temperature Measurement of Rotating Gears under Load

As gear engineers we are often asked to predict whether gears will fail by scuffing or micropitting in certain applications. AGMA and ISO offer their respective information sheets or standards to assist with these predictions. The calculations eventually boil down to lubricant film thickness, surface roughness, lambda ratio, and instantaneous contact (flash) temperature. One thing that has been drilled into my head since my early days as an engineering student is that models and calculations are only as good as the data they are fed. It is well known that the viscosity of a lubricant changes with temperature as shown in Figure 1. In micropitting calculations, the temperature that determines viscosity (and subsequently lambda ratio) is referred to as bulk or tooth temperature. Unfortunately, for a variety of reasons the tooth temperature cannot always be accurately determined. The bulk tooth temperature is also a significant portion of the calculation of instantaneous contact temperature in a scuffing calculation. AGMA 925 outlines a mathematical method to approximate the tooth temperature but the results are difficult to verify. There was a need to develop a method to do so experimentally.

vol26 fig1

Figure 1: Temperature Dependence of Lubricant Kinematic Viscosity 

Recently, GRI was asked by a single client sponsor to measure tooth temperature at load and speed for a variety of conditions. The sponsor was developing computer models to predict tooth and flash temperature in their production gearboxes and they needed experimental data to tune their models. GRI has made similar measurements in the past for several Aerospace Bloc consortium projects, but those were all using spur gears typically used in surface durability/scuffing tests. In this instance, the sponsor requested that helical gears representative of automotive transmission gearing be used. 

The tooth temperature was measured by precisely locating thermocouples at varying depths below the surface of the gear tooth, in the center of the face width at three profile locations. The data from several teeth at different depths was then used to establish a trend to extrapolate and determine the tooth temperature at the surface. There were numerous challenges to overcome. The first of which was installation of the 0.030 inch diameter thermocouples onto the gear. Conventional EDM (electrical discharge machining) was used to accurately place holes into the sides of the teeth. A method was developed to accurately measure the hole termination location (depth below the tooth surface) on the teeth after machining. An example of one hole location is shown schematically in Figure 2.

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Figure 2: Schematic of Thermocouple Hole for EDM Planning

The thermocouples are installed into the holes using a spring probe configuration to ensure contact is maintained between the tip and the surrounding steel, and then permanently attached with epoxy. The wires are routed through holes in the shafts to a slip ring assembly that allows measurement while rotating at speed. The data was acquired using NI LabView and post processed using DIAdem.

GRI’s standard power circulating (four-square) test rig was utilized for the project with a few modifications to the lubrication system to allow variation in oil jet direction and location. The test arrangement is shown in Figure 3. The torque, speed, lube flow rate and lube jet location were varied while temperatures were recorded. An oil off test was performed at the end of testing to obtain data during an extremely poor lubrication scenario. Temperatures were successfully recorded on six different teeth for all conditions. Measurements were also made on various parts of the test box hardware, as well as the ambient inside of the rig while the test was running. Videos were also recorded during testing showing the lube jet/gear interaction and the spray pattern generated during testing. The data is proprietary to the sponsor but a sanitized plot is given in Figure 4.

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Figure 3: Top View of Power Circulating Test Rig with Slip Ring – Instrumented Helical Gears are in the Test Gearbox


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Figure 4: Data Acquired During Tooth Temperature Measurement Project

To summarize, GRI continues to develop innovative solutions to help our customers achieve their goals in a budget friendly and timely manner. This project utilized existing test gears and was completed in less than six months. For more information on this or any testing service, please contact GRI today.

Education and Training

In order to assist with replenishment of the gear industry’s aging work force, the Gear Research Institute has developed a hands-on education program for students at both undergraduate and graduate levels. The results of the program are entry level engineers that have been trained in the basics of gearing. This involves incorporating engineering undergraduate students, at the junior/senior level and graduate students in the Institute’s research laboratory while being paid by a grant from the sponsoring industrial entity. Summer internships have also been arranged at the sponsor’s facility, so that the student and the sponsor have an opportunity to assess each other with future employment in mind.  

Typically, students get hands on experience by setting up and monitoring gear test equipment with additional training topics such as gear metrology, failure analysis, metallurgical characterization, vibration monitoring for failure detection, statistical analysis of test data and more. 

This newsletter’s student profile is of Alejandro Pardinas, Jr. Alejandro is pursuing his Bachelor of Science degree in Energy Engineering with a minor in Engineering Mechanics. Alejandro’s position was made possible through the generous support of GRI’s Corporate Members. He has been working in the GRI test lab supporting several projects since January of 2021. Alejandro has learned how to set up and operate the test equipment, document the testing properly, and has been trained in metallography. He has really been a big help during the pandemic as many of our students were not on campus and unable to work in the lab.

Alejandro will graduate in May and is currently job-hunting. His goal is to work in the energy sector in either wind power conversion (wind turbine drivetrains) or gas compressors and turbomachinery. In summer of 2019, Alejandro worked at Siemens Gamesa in Europe where he assisted in gear turbine assembly/repair. He worked with Höfler gear cutting machines and performed QC inspections prior to assembly..

vol26 alejandro pardinas

For more information about how you can support a student intern or sponsor a student project, please visit or contact Aaron Isaacson at 814 865 5832 or This email address is being protected from spambots. You need JavaScript enabled to view it..

Vehicle Bloc Revival

The Gear Research Institute was founded in 1982 with the primary focus of facilitating cooperative, pre-competitive research. Throughout the past forty years, we have conducted consortium or bloc style research efforts to investigate a wide variety of topics serving companies from all corners of the gear industry. A bloc is defined as a combination of parties sharing a common purpose. The idea is that each member company pays a membership fee and the funds are combined to achieve a common goal. The Aerospace Bloc has been operating since 1986. Member dues are $35K per year. There are currently thirteen member companies with five active projects. The Aerospace Bloc conducts  ~$400K of research each year, which is a tremendous value for the members. 

The Vehicle/Industry Bloc operated from 1989 – 2002. Founding member companies included Eaton Corp., Rockwell Intl., Ford Motor Co., Dorris Co., The Gleason Works, Harley Davidson, Bison Gear, The Timken Co., Clark Components Intl., Outboard Marine Corp., and General Motors Corp. Research topics were broad. According to documentation generated when the group was formed activities were focused on the following gear topics: lubrication, geometry, noise, vibration, load distribution, materials, manufacturing and gear performance. All of these topics continue to be of interest today. GRI’s capabilities have continued to grow in the time since the Vehicle Bloc last operated. We are well positioned to provide members with a significant return on their research dollar investment.  

Recently, several companies have approached GRI with a request to revive the Vehicle Bloc. This is a response to that request. We will need to determine one or more topics of mutual interest and agree upon an acceptable membership fee. At this early stage, all gear related topics are on the table – from traditional to innovative. Initially discussed topics range from performance characterization (of gear alloys, heat treatments, performance boosting post-processing treatments, surface finishing processes, steel cleanliness levels) to efficiency studies to investigation into additive manufacturing for gear applications. All suggestions will be considered.

We are planning to hold a virtual meeting for all interested parties. Click the link below to fill out our survey and be added to the contact list for more information.

Board of Trustees News

John O’Neil was chosen as a Class C, Member elected trustee in January 2021. John is Engineering Manager for gear tools at Star SU, a joint venture between Star Cutter Company and Samputensili (Bentivoglio, Italy). John has been involved with the Gear Research Institute since 2010 through Corporate Membership.  We would like to welcome John to the family and thank him for his willingness to serve GRI!

john oneil 200


It is with great sadness that we announce the death of a long-time friend of GRI. Thomas Doubts of Honeywell passed away earlier this year. He was one of a kind. He was a great mentor and friend. Tom served on the GRI Board of Trustees for almost 20 years. Tom worked for many aerospace companies throughout his career, demonstrating his drive system and gearbox expertise along the way. Tom was very supportive of GRI. So much so, that he was single handedly responsible for three new Aerospace Bloc research consortium member companies during his tenure at each. Tom is already missed.

vol26 tom doubts

Other News

GRI would like to remind readers to attend the AGMA Fall Technical Meeting on November 1-3, 2021 in Chicago, IL and the newly rescheduled International Conference on Gears 2021 to be held September 12-14, 2022 in Garching (near Munich), Germany.

Employment Opportunities

Several years ago, a few Corporate Member companies requested that we add a “Job Postings” section to the GRI website for gear and drivetrain related positions. This service was (and continues to be) offered free of charge to our Corporate members and sponsors. There are currently very few active job postings on the site. If you’re company has a job opportunity that you would like to have publicized, please contact Aaron Isaacson at This email address is being protected from spambots. You need JavaScript enabled to view it..


The Gear Research Institute is a non profit corporation. It has contracted with the Applied Research Laboratory of The Pennsylvania State University to conduct its activities, as a sponsor within the Drivetrain Technology Center. The Gear Research Institute is equipped with extensive research capabilities. These include rolling contact fatigue (RCF) testers for low- and high-temperature roller testing, power circulating (PC) gear testers for parallel axis gears with a 4-inch center distance (testers can be modified to accommodate other center distances), single tooth fatigue (STF) testers for spur, helical and spiral bevel gears, and gear tooth impact tester. Extensive metallurgical characterization facilities are also available at Penn State in support of the Gear Research Institute. For further details on our testing capabilities please go to or call Aaron Isaacson, Managing Director, at (814) 865-5832. 

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