Automatic tension control mechanism for a drive belt

摘要

A belt tension controlling mechanism has a spring member which operates on a pulley support bracket to establish a tension in a belt trained on the pulley. The spring member surrounds a threaded sleeve which is rotated by a pair of selectively operable one-way ratcheting clutches which are simultaneously driven in opposite directions by a vacuum motor. The rotation of the sleeve results in linear meovement of a shaft connected to the pulley support bracket to thereby increase or decrease the belt tension, depending upon which clutch is operable.