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Traditionally manual clutch actuation for automobiles was a spinoff from hydraulic brake technology namely heavy steel or cast iron cylinders, steel pipes and rubber hoses. Because of this archaic, inefficient and expensive approach to providing a mechanical advantage, an alternative lower cost system of cable operation gained popularity throughout the industry. However, the 1:1 ratio of a cable plus routing problems, NVH issues, efficiency losses and the need for complex adjustment mechanisms, opened up the opportunity for a rebirth of the old hydraulic concept. The goal was to design a system with a totally new approach that would meet the following criteria: High efficiency, increased temperature resistance, increased durability, reduced package size and weight, cost competitive with cable systems, and finally to take advantage of the latest advances in materials and processes.

The object of this paper titled “Electronic Shift for Automatic Transmissions” (ESAT), is to describe the latest developments in remote vehicle shifting systems or shift-by-wire for passenger vehicles and light trucks. Also, included in this paper is a description of the system, hardware and software development, testing and vehicle installations. The ESAT system, with its 2 or 3 module concept, provides packaging flexibility and offers the interior designer complete freedom for ergonomic styling. The system prevents the occurrence of shift linkage “PRNDL” misalignment in that it is pre-adjusted. It also improves transmission reliability by providing enhanced features such as; ‘automatic cycle to park’, ‘shift lock’, and ‘speed lockouts’.