Hydraulic control apparatus for automatic transmission for motor vehicle

摘要

A hydraulic control apparatus for controlling a shifting action of a hydraulically operated frictional coupling device of an automatic transmission connected to a vehicle engine, from a neutral position to a forward drive position, in response to an operation of a shift lever. The apparatus includes a shift control valve operable in response to the shift lever, between a position for supplying a fluid to the coupling device for engagement thereof, and a position for discharging the fluid from the coupling device for disengagement thereof, a flow control device for controlling a rate of flow of the fluid between the shift lever valve and the coupling device, a fail-safe fluid passage disposed between the shift lever valve and the coupling device, for fluid communication between the shift lever valve and the frictional coupling device, irrespective of an operating position of the flow control device, and a controller for controlling the flow control device so as to restrict the fluid flow into or from the coupling device after an engaging or disengaging action of the frictional coupling device is actually started.