| 摘要 |
A hydraulic control apparatus of automatic transmission comprising a hydraulic pressure source 51, hydraulic paths L32, L31, hydraulic servos 82, 81 for operating friction elements C-2, C-1 which are coupled with the hydraulic source and the hydraulic paths, a control device arranged on the hydraulic paths L32, L31, for operating engagement release through supply/removal of hydraulic pressure to the hydraulic servos 82, 81, and valves 55, 64, which are arranged on the hydraulic path L31, for cutting off hydraulic pressure from the hydraulic pressure source to the hydraulic servo 81 with hydraulic pressure in the downstream side of the control means as signal pressure. The hydraulic control apparatus of automatic transmission arranges the second valves 60, 60A on the hydraulic path L32 for cutting off hydraul pressure to the hydraulic servo 82 and the signal pressure to prevent a shift to other forward speeds caused by engagement of the friction element C-1 due to failure during a forward speed through engagement of the friction element C-2, and enables achievement of two forward speeds through the engagement of the friction element C-1 or C-2 during failure. <IMAGE> |
