Abstract

A sprocket (S) for a chain driven power transmission system used on an internal combustion engine. Severe ITVH (Noise, Vibration, Harshness) characteristics associated with a chain engaging the sprocket is damped by two annular rings (R1, R2) that are loosely positioned on either side of the circumferential row of teeth. The inner diameters (ID1, ID2) of each of the annular rings (R1, R2) form cavities between the annular rings and the sprocket grooves. Pressurized viscous fluid is supplied to each cavity via channels in the hub of the sprocket to cushion the impact of each roller of the chain as it engages each row of teeth during engine operation. The pressure of the viscous fluid creates a resistive force to minimize the severe impact noise experienced by non-damped sprockets.