A Practical Approach to Automatic Transmission Reliability

A tailored reliability program was employed throughout the design and development of an electronically controlled fourspeed automatic transmission. This paper describes the reliability trade-off study used to select the control system design philosophy and details the development of specific component reliability targets from the overall system requirements.

A unique adaptation of the transmission electronic control system has enabled an extensive data collection program to be completed. From this information a detailed life cycle profile was defined based on various end user operating conditions and specific customer durability tests. The results of this program are presented together with a comparison against the original component life targets set at the start of the transmission design.