| 摘要 |
PURPOSE:To eliminate unnecessary leakage of hydraulic coil from a pressure reducing valve, by releasing the operation of the pressure reducing valve when the hydraulic pressure downstream of an orifice disposed between a hydraulically engaging element and a shift valve exceeds a predetermined value. CONSTITUTION:There is provided a release means 21 for detecting the hydraulic pressure P3 downstream of an orifice 15 disposed in a seventh oil passage L7 which is communicated with a third shift stage hydraulic clutch C3, and for releasing the operation of a pressure reducing valve 20 when the hydraulic pressure P3 exceeds a predetermined value. The release means 21 is incorporated in the pressure reducing valve 20, and is composed of a pressure receiving surface 20C for pressing the valve rightward and an eighth oil passage L8 branched off from the seventh oil passage L7, for applying the hydraulic pressure P3 to the valve, and therefore, even in a low throttle valve opening degree range, if the pressure P3 increases due to damping action by an accumulator 17, exceeding the predetermined value, the operation of the pressure reducing valve 20 is released, so that the line pressure is led to the downstream side of the pressure reducing valve 20 without being decreased. |
