Operating device for controlling an operable control element of a vehicle transmission

摘要

The device has an electric motor (3) which rotates a shaft through worm gearing to cause a crankpin (10) to operate a master cylinder piston (12) through a rod (11). The rod is biassed by a spring (25). Further spring biassing which varies with the movement of the piston is provided by an arrangement (50) comprising a spring-biased roller acting on a cam (30) which rotates with the crank. In alternative arrangements the variable spring bias uses a linearly-moving surface with transversely-acting rollers or the roller may instead act on a rotary face cam.