Importance

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Abstract

A belt tensioning device for an endless drive belt for a vehicle accessories drive system. A housing is adapted to be mounted on an engine in a stationary position adjacent the drive belt and has a lever arm pivotally mounted thereon. An idler pulley is rotatably mounted on the lever arm and is movable into belt tensioning engagement by a torsional coil spring telescopically mounted about the pivot for the lever arm. A brake band ring is mounted on the lever arm and has a friction surface which is biased by the torsional spring into engagement with the housing to provide a damping force when the lever arm attempts to move in either a belt tensioning or non tensioning direction. The damping force is proportional to the torsional spring force generally throughout the tensioning range of the belt tensioner since the same coil spring provides both forces. A pivot shoe is removably mounted on the brake band adjacent the friction surface and a straight end of the torsional spring is engaged with the pivot shoe. The spring end is biased against a projection formed on the lever arm which acts as a fulcrum whereby the spring end biases the brake band into engagement with the housing through the pivot shoe. The angle of the spring end with respect to the pivot shoe effects the amount of damping force exerted by the brake band against the bracket through the biasing force of the spring.

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First Claim