Transmission control apparatus, having means for determining the completion of a shifting action of a coupling device with pressure adjusting accumulator

摘要

A hydraulic control apparatus for controlling a hydraulically operated automatic transmission, having a speed sensor for detecting the speed of a rotary member which changes due to a shifting action of a frictionally coupling device. The apparatus includes a device for determining, based on the detected speed of the rotary member, that the shifting action of the coupling device is completed, and a device which is operated in the event of a failure of the speed sensor, for determining that the shifting action of the coupling device is completed when a time which has passed after the moment at which the need to effect the shifting action was determined or at which a shifting command to initiate the shifting action was generated exceeds a predetermined time interval. Upon determination of the completion of the shifting action, an electronic device terminates an operation to control the back pressure of an accumulator for adjusting the fluid pressure applied to the coupling device.