AUTOMATIC TRANSMISSION

PURPOSE:To prevent shift shocks upon a gear shift from a second speed stage to a third speed stage by coupling a hydraulic actuator for operating a clutch, to an input shaft. CONSTITUTION:Upon a gear shift a second speed stage into a third speed stage, a direct clutch C2 slips in an initial engagement condition even high centrifugal hydraulic pressure is effected by rotating the hydraulic actuator 40 at a high rotational speed in association with the rotation of an input shaft 26 since only a small amount of hydraulic oil is fed to a piston 51 in the actuator 40 at an initial stage of the gear shift. Further, a large amount of hydraulic oil is gradually fed so as to move the piston 51 leftward, gradually, overcoming a spring. When the clutch starts to shift from slipping condition into an engaging condition, the rotation of the input shaft 26 starts to steeply decrease, and simultaneously, centrifugal hydraulic pressure is abruptly reduced. Accordingly, the direct clutch C2 engages smoothly while gradually reducing affection by the centrifugal hydraulic pressure without shift shocks being generated.