Abstract: In a pulley type speed-shifting device with a belt trained between a pair of variable speed pulleys, a movable sheave of each pulley is driven by a cam mechanism. Each cam mechanism has a cylindrical cam arranged concentrically with a rotary shaft and a cam follower which is arranged concentrically with a rotary shaft and carries a rolling body which makes contact with the cam as it is rolling on a cam face. The movable sheave is driven in axial direction by either the cylindrical cam or the cam follower rotating around the rotary shaft and rotating relatively to the other. As the cam follower makes contact with the cam face through the medium of the rolling body, resistance is small and the transmission ratio can be shifted with light handling force.

Abstract: In a speed-shifting device of a variable speed pulley type, a transmission ratio is changed by an inversely synchronized operation between a movable sideplate of the driving and driven pulleys. The tension is given to a belt by a bias mechanism biasing the slack part. In addition, the bias mechanism can be arranged to be movable for decreasing the tension of the belt to serve as a clutch mechanism interrupting the power transmission between the pulleys.

Abstract: A pulley type speed-shifting device is provided with a driving pulley and driven pulley mounted on each transmission shaft which are parallel, and a belt member is trained between both pulleys. A moving member is connected for movement in the axial direction with one sideplate of the driving pulley and is axially moved on the movable sideplate through screw motion caused by relative rotation around the transmission shaft. A speed-shifting pulley mechanism is provided for rotating the moving member relatively around the transmission shaft to change the transmission ratio between the transmission shafts in accordance with a required mode change.

Abstract: This disclosure relates to a belt-drive method and apparatus wherein the rotational force of a drive shaft is accompanied by minute fluctuations in the angular velocity, and a driven shaft has rotational inertia. A one-way clutch is provided in the belt drive, which forms a selective interruption of the rotational force transmission through the belt drive while the angular velocity at the drive shaft side is decelerating, the force being transmitted only while the angular velocity is increasing.