Manual transmission efficiency testing and evaluation with motoring and absorbing DC dynamometers at the transmission input and output were conducted at Southwest Research Institute (SwRI). This system was configured with 0.25-percent accurate slip-ring type in-line torque transducers to allow precise torque measurements.

Precision measurements were made to distinguish performance effects associated with:

Gear quality
Gear endplay
Gear backlash
Windage
Churning losses
Case deflection

Testing and evaluation consisted of operating the transmission at approximately 7 different "engine driving" torque conditions, 3 different "rear wheel driving" torque conditions and 12 speeds.

Testing and evaluation was conducted at one lube oil temperature approximating the fluid temperature as measured in the vehicle testing at the end of the EPA city cycle. To eliminate fluid-related efficiency effects, the fluid temperature was maintained within a ±5 °F band for the duration of the testing.

To approximate the actual vehicle configuration, the transmission test stand was adjusted to the engine mounting angle. Testing at the engine mounting angle is critical to replicate actual turbulence, churning and windage losses.

To eliminate any slippage across the clutch plate and friction plate, a special fixture was fabricated to drive the gearbox directly.

SwRI's manual transmission testing capabilities include vehicle applications having 1.6 to 8.0L engines.

For more information about our drivetrain engineering capabilities and past performance briefs, or how you can contract with SwRI, please contact Douglas Fussner at dfussner@swri.org or (210) 522-3972.

drivetrain.swri.org

Contact Information

Douglas Fussner

Drivetrain Design and Development

(210) 522-3972

dfussner@swri.org

drivetrain.swri.org

Related Terminology

transmission test
facility

transmission testing

automatic
transmissions

drivetrain database

drivetrain
engineering

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Southwest Research Institute^®(SwRI^®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 11 technical divisions.

December 28, 2012