Hydraulische Steuerung für ein Fahrzeuggetriebesystem, welches Ventile enthält, die die Einschaltung des Rückwärtsganges verhindern

摘要

A hydraulic control apparatus for a vehicle power transmission for transmitting power from an engine to a drive wheel a reversing mechanism (16) having a reverse position established by a hydraulic actuator (70). The apparatus includes a reverse inhibit valve (420) disposed in a hydraulic line leading to the hydraulic actuator and having a reverse inhibit position for inhibiting the mechanism (16) from being placed in the reverse position and a non-inhibit position for permitting the mechanism to be placed in the reverse position. The apparatus uses a first and a second pilot pressure generating device (344, 346; 392, 394) for producing a first and a second pilot pressure (Psol4, Psol5), respectively. A relay valve (380) is provided for producing a first hydraulic signal for establishing the reverse inhibit position of the reverse inhibit valve, based on one of combinations of operating states of the two pilot pressure generating devices, and a second hydraulic signal for establishing the non-inhibit position, based on the other combinations.