OIL PRESSURE CONTROL DEVICE FOR AUTOMATIC TRANSMISSION

摘要

PURPOSE:To prevent worsening of a gear shift shock through prevention of production of an engine brake sate at low and middle speed stages owing to failure of an automatic transmission to electrically set and engine brake state at a reverse stage and low and middle speed stages. CONSTITUTION:In an automatic transmission wherein control is effected by the same solenoid valve S3 to bring an auxiliary transmission part into an overdrive state at a reverse stage and bringing an engine brake into an effective sate at low and middle speed stages, an overdrive state and a non-engine brake state at low and middle speed stages are set by the same control state as that of the solenoid valve S3, and the signal pressure of the solenoid valve S3 to set a non-engine brake state at the middle and low speed stages is reversed by a switching valve 130. Thus, even when it is erroneously detected that a running range at the low and middle speed stages is a reverse stage, an engine brake is not effective at the low and middle speed stages and a gear shift shock is prevented from occurring.