| 摘要 |
Pulleys are provided with load cam mechanisms which exert axial forces corresponding to transmitted torque, and actuator means such as ball screw mechanisms which shift the movable sheaves of both pulleys in axial direction, wherein the axial forces occuring at the pulleys are carried by their shafts and do not act on the housing. A counter shaft is located between the primary and secondary shafts, the countershaft being rotated to drive the actuator means through gearing such as gearwheels, to alter the drive ratio. During power transmission, the axial forces acting on the movable sheaves of primary and secondary pulleys are converted into torque by the actuator means, where the torques are transmitted to the counter shaft in the form of counteracting torques, so that alteration of drive ratio can be made with slight effort on the counter shaft, equivalent ot the difference between the counteracting torques. By using a non-uniform cam mechanism for the actuator means, or by using non-circular gearwheels for the gearing, the displacements of the movable sheaves are matched with their proper displacements determined by the belt.
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