| 摘要 |
PURPOSE:To reduce a drag torque of a hydraulic clutch by arranging a means for controlling oil pressures supplied to a pressure chamber of a clutch thereby lowering the oil pressure when the clutch is brought to an engagement start point. CONSTITUTION:A piston 46 is pushed forward by an oil pressure from a pressure control valve means while a valve piece 70 causes a pressure plate 42 to move. The piston 46 then moves to an engagement start point due to the movement of the valve piece 70 resisting the force of a spring 71. Here, a CPU 152 brings a flow rate control valve 166 to a released condition so that the pressure of working oil supplied to a pressure chamber 56 is lowered to a set pressure. Accordingly, the pressure in the pressure chamber 56 is sufficiently discharged regardless of a pressure loss generated in an oil discharge passage extending from the pressure chamber to a tank 58. As a result, the thrust of the piston 46 becomes smaller and therefore a drag torque of a clutch 22 becomes smaller and the durability is improved accordingly. |
