| 摘要 |
PROBLEM TO BE SOLVED: To prevent degradation in responsiveness due to the delay of the releasing operation of a 3-4 clutch at the time of a shift in which working pressure is exhausted from the releasing member of a 2-4 brake and the fastening chamber of the 3-4 clutch from a state that working pressure is supplied to the fastening chamber and the releasing chamber of the 2-4 brake and the fastening chamber of the 3-4 clutch and at the time of a shift by a manual operation under small engine load, in an automatic transmission provided with the 2-4 brake which has the fastening chamber and the releasing chamber and in which friction elements are fastened by a second speed and a fourth speed and the 3-4 clutch which has the fastening chamber communicatable with the releasing chamber and is fastened by a third speed and the fourth speed. SOLUTION: When engine load is smaller than a prescribed value at the time of a 3-2 shift, servo apply pressure is lowered by a first DSV(duty solenoid valve) so that the differential pressure of servo apply pressure and servo release pressure of a 2-4 brake may be smaller than when engine load is larger than the prescribed value. As a result, servo release pressure and 3-4 clutch pressure are made to be promptly exhausted. |
