| 摘要 |
PROBLEM TO BE SOLVED: To prevent blow-up of an engine speed caused by the operation delay of a switch means at the time of a prescribed gear sift under an extremely low temperature in an automatic transmission provided with a first friction element having a fastening chamber and a releasing chamber, second and third friction elements having fastening chambers and the switch means selectively making the releasing chamber of the first friction element communicated with the fastening chamber of the second friction element or the fastening chamber of the third friction element. SOLUTION: At the time of 4-2 gear shift in which working pressure is supplied to a forward clutch in a state that a 2-4 brake is fastened, working pressure of a 3-4 clutch is exhausted and the releasing chamber of the 2-4 brake is switched from a state that the releasing chamber is communicated with the forward clutch to a state that the releasing chamber is communicated with the 3-4 clutch, working pressure P fw 2 to be supplied to the forward clutch is set to pressure P fw 2o which is lower than that at the time of a normal temperature so as not to release the brake even if working pressure P fw 2 is introduced into the releasing chamber of the 2-4 brake at the time of an extremely low temperature. |
