Patent ID: 6959682

Claim:
An engine balancer comprising: first and second rotatable balance shafts adapted to be driven in timed relation to rotation of an engine output shaft; a rotary output member drivable by the output shaft; first and second rotary input members operative respectively to drive the first and second balance shafts; a drive chain connecting the output and input members such that the first input member is driven directly by the chain from the output member and the second input member is driven by the chain from the first input member whereby the chain is capable of producing in operation a vibration causing an audible chain whine in associated engine structure carrying the balance shafts; the first input member being connected with the balance shaft by mating internal and external splines connected one with each of the first input member and the first balance shaft and positioned in loose meshing engagement for drivingly connecting the first input member with the first balance shaft, wherein the splines are relatively wide and shallow, having substantially greater width than their radial extent, which is sufficient to maintain engagement should angular clearance between the splines be closed; and a splined isolator ring disposed exclusively between and engaging the internal and external splines, the isolator ring being formed of a compliant material to minimize vibration transmission to the associated engine structure.