Drivetrain Technology Center

Increasing performance and reducing costs

of mechanical power transmission systems and components

In collaboration with the Gear Research Institute, the Drivetrain Technology Center houses the most comprehensive gear – and gear materials – test facility in the nation.

Based on algorithms developed over the last few decades that correlate vibrations in a gear mesh to the geometry, load and accuracy to which the gear is fabricated, our contributions to gear design and metrology include:

  • Evaluating and correcting for gear noise
  • Developing gear design methodology for low vibration
  • Advancing the state of gear measurement
  • Developing methods for gear prognostics

The DTC came into being in 1992 under the auspices of the U.S. Navy MANTECH program. It is currently sponsored by various federal agencies and the gear and transmission manufacturing industry (aerospace, automotive and marine) in the United States and abroad. R&D services to the gear/drivetrain industry include gear manufacturing/process support, performance testing and characterization of all things gear related, including metrology, metallurgy, failure analysis, prognostics, etc. The DTC also operates the AGMA, ASME Gear Research Institute, under a multi-year contract.

The primary objectives of the R&D efforts at the DTC are to increase performance and reduce costs of mechanical power transmission systems and components. There are several metrics of performance. They include higher power density, increased component durability, and reduced operational vibration and noise. To fulfill these objectives, a variety of sponsored projects focusing on manufacturing, materials, and metrology have been undertaken or are ongoing at the DTC.

In the area of manufacturing, we spend a considerable amount of effort characterizing the impact of current processes on the durability of transmission components such as gears, while focusing efforts in developing novel manufacturing processes for the same. Characterizing the durability of various advanced steels for gear applications and optimizing their performance is a major component of the DTC’s efforts in the area of materials.

The DTC is very well equipped with the necessary hardware to conduct R&D efforts in these areas.  A battery of rolling/sliding contact fatigue testers, tooth bending test facilities, and low speed and high speed re-circulating gear testers are available. A gear metrology facility equipped with an M&M CNC gear inspection machine, a MAAG gear checker and a ZEISS coordinate measuring machine (CMM) are also available at the DTC. Also resident at the DTC is the world’s first production capable, double-die gear ausform finishing machine (discussed below).

High Strength Powder Metal Gears for Vehicle Transmissions

It is well established that complex metal parts can be manufactured more economically with powder metal (P/M), especially in large quantities.  However, P/M components generally do not have the strength and durability to replace wrought metal parts in critical power transmission applications.
In a project sponsored by the United States Army/TARDEC/NAC, the DTC is working very closely with a manufacturer of P/M components to enhance the strength and durability of P/M (spur and helical) gears for vehicle transmissions at a lower cost than current gears made from wrought steel.

The key to enhancing the strength and durability of P/M gears is the Penn State developed finishing process called Ausform Finishing.

This is a thermomechanical process that sequentially combines the three operations of induction heating, marquenching and roll finishing to produce a hardened and high quality gear.  In this process the carburized gear is contour induction heated to convert the carburized layer to the austenitic phase, immediately followed by marquenching and roll finishing at an elevated temperature, while the steel is still in the austenitic phase. The roll finishing operation produces a gear with very high surface finish and accuracy and the final quenching produces the high hardness/high strength martensitic phase.  The result is a finished gear – ready for assembly after deburring.

To date, tests on P/M gears completed by ausform finishing – on the DTC’s world’s first gear ausform finishing machine – have validated this approach.  It is anticipated that the introduction of P/M gears into vehicle transmissions will occur in the very near future.

Development of Design Allowables for Advanced Gear Steels

In response to DoD requirements for extended rotorcraft gear box operation under “loss of lube” conditions, the United States steel industry has introduced a variety of “High Hot Hardness” gear steels.  The DTC, under the sponsorship of the Gear Research Institute’s Aerospace Bloc (consortium of aerospace gear manufacturers), is conducting several projects to characterize the contact fatigue, bending fatigue and scoring resistance properties of gear made from these steels.

Test specimen design details, specimen manufacturing processes, and test conditions for the various assessments for this project were arrived at in a collaborative and cooperative manner within the Bloc. Gear evaluations were conducted under carefully controlled conditions and the data obtained shared between the participants.  The actual gear design stress allowables is determined from this data by each individual company, based on their own internal procedures.  Several “High Hot Hardness Steels” are being evaluated in this project.

Gear-Vibration Diagnostics Software Project with USCAR

USCAR is a consortium of General Motors, Ford, and Chrysler. In an earlier project, a Drivetrain Center faculty member (W. D. Mark) had developed a method of measuring manufacturing deviations on a single spur or helical gear and predicting from these measurements the vibratory excitation (transmission-error contribution) caused by these manufacturing deviations that would take place if the measured gear were run in meshing action with another gear. The mating gear is not required.  After computing the rotational-harmonic transmission-error spectrum caused by the measured errors, the user of this software can compute the manufacturing-error contribution on the working surface of each tooth of the measured gear that is the cause of any user-specified rotational harmonic (ghost tone) of the computed transmission-error spectrum, thereby providing diagnostic information useful for eliminating the manufacturing cause of the chosen single or multiple harmonics. USCAR has contracted with the Drivetrain Technology Center to provide a user-friendly package that will enable the user to measure any external or internal spur or helical gear, and to compute the transmission-error spectrum and diagnostic information as described above.

ARL is committed to our employee’s health and well-being by supporting Penn State initiatives, local health officials, and government leaders in preventing COVID-19 in the workplace.

Our employees whose work or research can be done remotely, from home, are doing so. We have also given the opportunity of a flexible work schedule to assist our employees who have other obligations to consider. For those whose work or research requires them to be in our laboratories, offices, or on campus, we are following all protocols necessary to reduce the spread of COVID-19, including mandatory mask training, strict safety procedures, and a network of contacts for reporting any ill-feeling symptoms.

As new employees join our workforce, the above guidelines apply. 

You can be confident that we will maintain our vigilant enforcement of all COVID-19 protocols in our workplace to ensure the health and safety of everyone.

Our strength comes from our people… we are a diverse group of professionals who hail from all over this great Nation, with all kinds of experience and expertise. As a team, we will get through this together with patience, diligence, vigilance, and resilience.