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 my graduation in 1972 from Technical University in Cracow, Poland with an MS in mechanical engineering. Huta Stalowa Wola (HSW) had just entered into license agreements with the International Harvester Company (IHC) to produce construction equipment and with Clark Equipment Company AG to produce drive and steer axles for construction equipment.

Roman Cisek.

Mechanical engineers with good command of technical English were scarce at that time, so I, being one of them, was involved in a transfer of technical “knowhow” where gears were a quite important part of the business. During 1973-1975, I was able to visit all gear manufacturing locations for IHC and Clark Equipment, learn about their gear manufacturing equipment, materials, heat treatment, and quality control. These companies had very controlled methodology for gear design, material specifications and quality requirements, and these methodologies were fundamental to my subsequent career in the field of gear design and technology.

During 1975-1981, working in the drive train design department, I spent most of my time analyzing gear designs used in Clark Equipment axles to help application engineers with proper axle selections for loaders, handlers and cranes. My special interest at that time was with bevel gears, because there were many different spiral bevel ratios used in the axles and still new ratio requests.

In 1975, I took a 5-week training course at Gleason Works – Rochester NY to learn more about bevel gears. Arthur Bragg, Jr. was the manager of the Gleason Training Department at that time and he kindly provided me with many Gleason publications upon my request during the training. Finally, at the end of the training, fatigued with my requests, he invited me to the training department stock room.” I took one of each publication and got a unique collection of Gleason publications; they are still very useful to me today.

In 1978 I took a 2-week course in advanced engineering training at Gleason Works to learn calculations of dimension sheets and gear cutting summaries and tooth contact analysis. The importance of spiral bevel gears used in axles and crawler tractor steering mechanisms prompted the development of computer software to calculate dimension sheets and machine settings, where I was responsible for providing the formula documentation and flow charts. We were quite successful in the software development, and our design engineering group even got a remote terminal to work with the IBM 370 mainframe computer, predominately used for financial departments. Gear calculation software for parallel axis gears was also developed based on my algorithms.

During 1981-1992 Poland and HSW went through a turbulent time. The old regime could not tolerate the activity of the Solidarity Union movement and martial law was imposed in the country on Dec 13, 1981 — along with trade embargo consequences. We were experiencing difficulties in getting components for steel production (molybdenum) to make 8620 and 4817 steels.

This prompted my interest in gear steel design and manufacture, where I finally developed two steel grades without molybdenum, which met the requirements for our gear products regarding the base and case hardenability. The International Harvester CHAT (Computer Harmonized Application Tailored) system was a great tool for the selection and design of optimum-composition gear steels. Gear test samples were made from experimental heats and successfully tested for strength and durability with four square machines.

The knowledge gained from the experimentation with gear steel composition and gear testing for surface durability proved to be my biggest advantage in my future career as a gear design engineer.

At the beginning of 1990, I realized I had to look for another employer to continue with my career in gear design and development. I was in contact with several companies of similar size as HSW, including John Deere. I still have the letters from Deere assuring me that my resume is on file for future opportunity.

In the summer of 1993, I arrived in Chicago, the Windy City I had known well from my previous work with IHC. Waiting for my real opportunity, I worked as a gear engineer for Gearex Fulton and Chicago Gear until that opportunity came in the middle of 1995. I joined the John Deere Product Engineering Center in Waterloo, IA, on July 10, 1995 as a gear design engineer responsible for parallel axis gears.

One of my first projects was to look at the case depth specifications and determine if there’s just enough case depth to provide adequate durability and strength. This action resulted in a case depth calculation sub-routine which serves to adjust case depth relative to the load and stress.

Tooth flank surface durability improvement has been quite the challenge for most gear design engineers and I concentrated my efforts in this direction. Surface engineering for carburized gear flanks is a complicated task and success is difficult to achieve. My research work in that area resulted in a patented surface engineering process, with the patent US8062094 granted in 2011.

Around year 2010, I initiated an extensive gear surface durability testing program. The goal was to determine surface durability for gears made of popular U.S. carburizing steels and various gear manufacturing technologies. Initially, the testing of several grades of steel and technologies was done at the FZG, Munich, Germany, with the purpose of comparison with the already-existing surface durability data of European and other carburizing gear steels. In parallel to testing at FZG, surface durability testing at WZL Aachen was run with various materials and technologies and according to my testing specifications.

Starting in 2015, I began to run gear surface durability testing at the Gear Research Institute located at Penn State University. They use a special set up with a four square test machine, which allows for more flexibility in the way the testing is conducted. I ran several gear steel grades and gear manufacturing technologies for spur gears and high contact ratio gears using my test specifications.

In 2018, I started gear surface durability testing of high cleanliness gear steels at the OSU Gear Lab using their newest generation four square test machines. Several gear steels have been selected and tested so far. Again, the testing is conducted using my test specifications.

All these test programs significantly improved our gear design criteria and the ability to design gears that are efficient in manufacturing, providing required performance and durability expected by the customer.

Gear design work for agricultural tractors is quite challenging because of the wide range of operating conditions that need to be considered. The loads and speeds very a lot; imagine a vehicle that works at a speed range of 5 to 50 km/h and uses a 23-speed power shift transmission!! Design criteria for high speed and low loads are quite different than the criteria for the low speed, high loads, and require careful consideration of many factors to meet capacity, durability, noise and COST requirements.

As can be seen from my story, in addition to the regular gear design work to determine load distribution and stress levels, I was more involved in the strength side of the stress-strength equation for gear strength and durability determination. It is because I believe the stress side is quite straightforward, whether we use a particular gear rating standard or run final element-based calculations. The strength side however, still presents many challenges and a lot of opportunities for a cost-effective gear design.

About Charles D. Schultz 580 Articles
Charles D. Schultz is President of Beyta Gear Service and one of Gear Technology's technical editors.

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