Hydrauliksteuerung für ein Automatikgetriebe

摘要

An automatic transmission includes transmission mechanism having a friction coupling member for enabling engine brake, and a hydraulic control circuit having a pressure regulator valve for feeding a coupling pressure to the friction coupling member and a cutback valve for reducing the coupling pressure. This automatic transmission further has a cutback valve control device for suspending the cutback in a particular gear ratio in the engine brake enable range. Accordingly, in the engine brake enable range which requires a higher coupling pressure, a sufficient coupling pressure can be assured by suspending the cutback.