Patent ID: 7998008

Claim:
A power transmission pulley for decoupling a belt-driven accessory, the pulley comprising: a driving pulley element having an outer outline that is adapted to receive a belt, and a resilient element interposed between the driving pulley element and a receiver device for being coupled to said accessory, the pulley including a freewheel device of a ball, needle, or cam type disposed in series with the resilient element between the driving pulley element and said receiver device, the freewheel device serving to transmit power so long as the driving pulley element is driven by the belt, and serving to decouple the freewheel device when the driving pulley element is no longer driven by the belt, wherein the stiffness k of the resilient element satisfies the following relationship: k≦ 8π 2 ( f *) 2 I where f* designates a critical frequency of the system that is a frequency whereby a system response is the greatest and I designates the inertia of the accessory to be decoupled and further wherein: 2π 2 ( f *) 2 I <k.