| 摘要 |
PURPOSE:To prevent the occurrence of excessive speed change shock by providing a one-way valve for permitting the flow of oil only from a high-speed stage side oil pressure operating chamber to a low-speed stage side oil pressure operating chamber on a friction engaging element. CONSTITUTION:At the time of speed change from the first gear to the fourth gear, all of 1-2, 2-3, and 3-4 shift valves 64, 66, 68 are switched over to each high-speed stage position, the pressure of the second-gear apply chamber 2A of a band brake BB rises via a 1-2 accumulator valve 80, the pressure of the third-gear release chamber 3R thereof rises being delayed by the operating amount of a high clutch H/C, and the pressure of the fourth-gear apply chamber 4A thereof rises through a one-way orifice 104. In this case, if the rise of oil pressure in the high-speed stage side oil pressure operating chamber 4A is faster than the oil pressure in the low-speed stage side oil pressure operating chamber 2A, oil flows from the high speed stage side to the low speed stage side via a one-way valve 108 and the oil pressures in both chambers 2A, 4A are subjected to the oil pressure relaxing action of the valve 80 and gently rise. Hence, an excess of torque capacity at the time of engaging the band brake will not take place. |
