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Unacceptable
Reverse Shift Times at
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SwRI Project: |
03-5762 |
Client: |
Industrial Confidential |
Project Brief
This manufacturer's vehicle complained that the reverse shift took an excessively long period of time to occur or did not occur at ambient temperatures of −20 to −40°F. It was believed that the cause of the problem was excessive leakage about two elastomer seals.
Initially, Southwest Research Institute (SwRI) conducted statistical and worst-case tolerance analyses of more than 17 mechanical components that effected the axial and radial sealing surface about the seals. Computer-aided drawings were created that simulated these results. These results provided direction for conducting laboratory testing.
Laboratory testing consisted of simulating the various sealing surfaces through a range of positions at ambient and −40°F fluid conditions. As testing was conducted in a cold chamber, 14 precision eddy current proximity probes were used to monitor component positions and movements. The testing was repeated with parts that created different seal "squeeze" conditions.
Analysis of variable (ANOVA) statistical techniques were used to reduce the number of tests performed by allowing multi-variable changes to be effected through the testing sequence while providing information on the interaction of changing test parameters.
Analysis of laboratory test results indicated that a very narrow band of seal compression would provide sufficient fluid sealing to occur at low temperatures for acceptable shift times to be effected.
Selected hardware configurations were tested in the vehicle at ambient and −40°F with selected seal squeeze. SwRI was able to repeatedly, and on demand, produce the phenomena that caused the complaints, and similarly, could cause acceptable reverse shift times to occur.
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.
Contact Information |
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Drivetrain Design and Development (210) 522-3972 |
Related Terminology |
transmission test transmission testing automatic
drivetrain database drivetrain |
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| Design and Development | Engine, Emissions & Vehicle Research Division | SwRI Home |
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
