Patent ID: 8276480

Claim:
A drive mechanism comprising: a drive assembly including a driven element; a first driveshaft, configured to be engaged with the drive assembly, the first driveshaft configured to rotate in a first direction and relate a first assembly torque to the drive assembly and a first drive torque to the driven element; and a torque adjusting mechanism operatively engaged with the drive assembly and configured to relate a second assembly torque, opposite in direction to the first assembly torque, to the drive assembly, wherein the torque adjusting mechanism includes a second driveshaft, configured to rotate in a second direction that is opposite to the first direction and relate the second assembly torque to the drive assembly and relate a second drive torque to the driven element, and both the first assembly torque of the first driveshaft and the second assembly torque of the second driveshaft are applied to the driven element.