| 摘要 |
PURPOSE:To feed operating pressure always at the fixed timing at the speed change time when operating pressure is fed to a friction locking element, regardless of whether an operating pressure feed passage is filled with operating oil or contains air. CONSTITUTION:In an automatic transmission, a one-way orifice 66 formed of a shuttle ball 66a and a fixed orifice 66b is provided at an operating oil feed passage to a specified friction locking element in a hydraulic control circuit. This one way orifice is installed in a line 117 for feeding operating pressure to the release port 45c of a servo piston. In such constitution, a drain line 147 reaching a 3-2 timing valve 88 from the downstream part of the line 117 is branched, and a solenoid valve 90 is driven in such a way as to drain the line 117 by the 3-2 timing valve 88 for the specified time at the speed change time when operating pressure is fed to the release port 45c. |
