Patent ID: 8342993

Claim:
A synchronous drive apparatus comprising: a plurality of rotors including a driving rotor, a first driven rotor and a second driven rotor, the first driven rotor being adapted to be coupled to a first shaft that when rotated is configured to transmit to the first driven rotor a first periodic fluctuating load torque, the second driven rotor being adapted to be coupled to a second shaft that when rotated is configured to transmit to the second driven rotor a second periodic fluctuating load torque; a continuous loop elongate drive structure that is engaged to the plurality of rotors to transmit rotary power from the driving rotor to the first driven rotor and the second driven rotor; wherein the first driven rotor comprises a first non-circular profile having a plurality of first lobes arranged about the first non-circular profile so as to cooperate with the continuous loop elongate drive structure to apply a first opposing fluctuating corrective torque to the first driven rotor that at least partly counteracts the first periodic fluctuating load torque; wherein the second driven rotor comprises a second non-circular profile having a plurality of second lobes arranged about the second non-circular profile so as to cooperate with the continuous loop elongate drive structure to apply a second opposing fluctuating corrective torque to the second driven rotor that at least partly counteracts the first periodic fluctuating load torque; and wherein the first non-circular profile is different from the second non-circular profile.