| 摘要 |
<p>A changeover valve (7) is provided on an upstream side of solenoid valves (S2, S4, S5) for hydraulic engaging elements (C2, B1, B2). The changeover valve (7) is urged to the closed position by the hydraulic oil pressure of a plurality of hydraulic engaging elements (C1, C2, C3, B1) which are concerned with the speed changing. At the time of failure in which three or more of the hydraulic engaging elements are simultaneously engaged, the changeover valve (7) is changed over to the closed position to thereby lower the hydraulic oil pressure in the hydraulic engaging elements (C2, B1) on the downstream side of the changeover valve (7), whereby the simultaneous engagement is prevented. In the closed position, a hydraulic oil pressure of a predetermined pressure is inputted to the changeover valve (7) via an oil passage (L11). The chattering of the changeover valve (7) is thus prevented even if the hydraulic oil pressure in the hydraulic engaging elements (C2, B1) may be lowered. <MATH></p> |
