Abstract: A tensioner having a backstop device which allows free rotation of the pivot arm in a first direction but controls rotation of the pivot arm in a second, opposite direction. The backstop device permits a predetermined, limited amount of free rotation in the second direction and thereafter, employs a braking device to prevent rotation in the second direction if the torque that acts on the pivot art is less than a predetermined threshold.

Abstract: A tensioner having a backstop device which allows free rotation of the pivot arm in a first direction but controls rotation of the pivot arm in a second, opposite direction. The backstop device permits a predetermined, limited amount of free rotation in the second direction and thereafter, employs a braking device to prevent rotation in the second direction if the torque that acts on the pivot art is less than a predetermined threshold.

Abstract: 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.

Abstract: A serpentine belt drive system for an automotive vehicle comprising a drive assembly including an internal combustion engine having an output shaft with a driving pulley thereon rotatable about a driving pulley axis. A sequence of driven assemblies each has a driven pulley rotatable about an axis parallel with the driving pulley axis and a serpentine belt mounted in cooperating relation with the driving pulley and with the driven pulleys in a sequence which corresponds with the sequence of the driven assemblies when related to the direction of movement of the belt to cause said driven pulleys to rotate in response to the rotation of the driving pulley. The sequence of driven assemblies includes an alternator assembly including an alternator shaft mounted for rotation about a shaft axis. A hub structure is fixedly carried by the alternator shaft for rotation therewith about the shaft axis. A spring and one-way clutch mechanism couples the alternator pulley with the hub structure.