Patent ID: 7654925

Claim:
A chain and sprocket drive system comprising: a chain having a plurality of links interconnected by joints including a link pin so that the links are pivotable around a link pin axis relative to each other, the chain having teeth; and at least one sprocket having a central axis of rotation and a plurality of sprocket teeth, the sprocket teeth having sprocket engagement surfaces disposed to engage the chain teeth, the sprocket teeth and sprocket engagement surfaces spaced about the periphery of the sprocket, the sprocket engagement surfaces spaced a distance from the sprocket central axis effective to dispose the chain at a pitch radius defined by the distance between the sprocket central axis and the link pin axis of a chain link which has teeth engaged by the sprocket engagement surfaces, the sprocket engagement surfaces of the at least one of the sprockets disposed to engage the chain teeth to provide a sequence of at least a minimum pitch radius, at least a maximum pitch radius, and at least one intermediate pitch radii there between, the distance between adjacent link pin axes of links having teeth engaged with the sprocket substantially constant, and a pitch radii sequence including the minimum and the maximum pitch radii and an intermediate pitch radii continually repeating itself at least twice with each rotation of the sprocket for imparting tensions to the chain timed with respect to tension loads imparted to the system from other sources effective to reduce maximum chain tensions at one or more of peak tension speeds relative to the maximum chain tensions at the peak tension speeds where the sprocket is a straight sprocket.