Patent ID: 8246502

Claim:
A variable ratio drive assembly including: a first planetary gear device having an input shaft and an output shaft, with the shafts having a common rotational axis, an input gear attached to the input shaft so as to be drivingly associated therewith, an output gear attached to the output shaft so as to be drivingly associated herewith, a first carriage mounted for rotation about said axis, at least one planetary gear meshed with the input gear and output gear, the planetary gear being rotatably mounted in the carrier so as to be supported thereby and movable therewith, a ring gear fixed to the carrier so as to move therewith and therefore rotated about said axis; a pump gear meshingly engaged with the ring gear so as to be driven thereby; a first pump device drivingly connected to the pump gear so as to be driven thereby to provide hydraulic fluid under pressure; restriction means associated with the pump device and to receive said hydraulic fluid under pressure and operable to control the flow thereof so that said pump device applies a torque to said pump gear to thereby control rotation of said ring gear about said axis and therefore rotation of said output shaft; a second planetary gear device, said second device having a second input shaft and a second output shaft, with the second shafts having a common rotational axis, a second input gear attached to the second input shaft so as to be drivingly associated therewith, a second output gear attached to the second output shaft so as to be drivingly associated therewith, a second carriage mounted for rotation about the common axis of the second shafts, at least one second planetary gear meshed with the second input gear and the second output gear, the second planetary gear being rotatably mounted in the second carrier so as to be supported thereby and movable therewith, a second ring gear fixed to the second carrier so as to move therewith and therefore rotated about the common axis of said second shafts; a second pump gear meshingly engaged with the second ring gear so as to be driven thereby; and a second pump device drivingly connected to the second pump gear so as to be driven thereby to provide hydraulic fluid under pressure that is delivered to said restriction means, with the restriction means therefore being operable to control the flow from the second pump device so that the second pump device applies a torque to the second pump gear to thereby control rotation of the second ring gear about the common axis of said second shafts and therefore rotation of said second output shaft.