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An analytical tool which predicts the dynamic behavior of automobile engine cranking systems has been developed to reduce the amount of testing typically required during the starter system development process. A general dynamic model of a complete cranking system with all its components and principal operational modes was developed. The model was used to simulate the dynamic performance of an automotive engine starting system. Typical starter system performance characteristics are shown.

This paper is based on a prepared discussion which was presented at the CVT Panel (Session #1PC26) during the 1985 SAE International Congress and Exposition. The paper reviews the background of this rather intriguing class of variable-ratio mechanical drives and briefly summarizes the past worldwide research which led to the development of several automotive traction drive CVTs. The “toric” CVT, which was a subject of extensive research and development effort at General Motors and elsewhere, is used as an example for illustrating typical traction drive characteristics. Further, discussion is presented of the desirable attributes of traction drives, as well as of the various technical concerns arising from the power transfer through traction forces of a rolling contact under conditions unique to automotive transmission applications.

This paper discusses the principle of operation and dynamometer test results of a fixed ratio, planetary speed reducer which uses preloaded, lubricated rollers for transmittal of power. The unit features a torque actuated, automatic preloading mechanism which prevents roller slippage even under severe overload and greatly improves reliability, life, and efficiency of the drive. Test results indicate efficient, quiet, and vibration free operation at pitch line velocities up to 30,000 fpm, such as might be encountered in turbomachinery. Examples of roller traction drives ranging from 500 to 3 hp tested in several applications are also briefly discussed.