Timing belt tensioner with stops controlled by frictional brake

摘要

A tensioner (10) features a backstop device (40) which allows free rotation of the pivot arm (20) in one direction but not the other. Reverse rotation is prevented by friction that is able to resist torque on the pivot arm (20) under ordinary operating conditions which otherwise could permit belt tooth-skip to occur. In disclosed embodiments, the backstop device (40) includes a stop sleeve (50) and a clamp holder (60) which are axially interlocked and are able to rotate relative to each other. A clutch spring (80) surrounds permits relative rotation between the stop sleeve (50) and the clamp holder (60) in one direction but not the other. A clamp (70) retained within the clamp holder (60) frictionally engages the pivot shaft. A viscous coupling may be used in place of the frictional clamp.