Hydraulische Steuerungsvorrichtung für ein Mehrgangautomatikgetriebe

摘要

A hydraulic control device for a multi-speed automatic transmission includes friction engagement elements, several hydraulic servos that engage and release the friction engagement elements, solenoid valves for engagement control, and a sorting switch valve that allocates engagement pressure from at least one of the solenoid valves for engagement control to two of the hydraulic servos. The sorting switch is switched between a first position that supplies engagement pressure to one of the two hydraulic servos in at least a Reverse, non-drive range and a specific Forward gear range, and a second position that supplies engagement pressure to the two hydraulic servos in other than the Forward range. The hydraulic control device supplies the engagement pressure to the two hydraulic servos when an all-solenoids-off failure occurs and the sorting switch is in the second position, and cuts off a source pressure to all solenoid valves when an all-solenoids-off failure occurs while the sorting switch valve is in the first position.