| 摘要 |
PROBLEM TO BE SOLVED: To detect the functioning state of a piston to engage the brake discs of an automatic transmission without depending on the driving oil pressure of the piston. SOLUTION: An automatic transmission is provided with a control means 6 set up in such a way as in the case where a detection signal issued when a hydraulically driven piston 53 begins the pressing of brake discs 51a, 51b to be mutually engaged by its pressing force is inputted, after the valve opening rate of a solenoid valve 3 to control a pressure oil for driving the piston 53 lowers once, it increases again; the first and the second electrodes 71, 511 severally provided on the opposite faces of the piston 53 and of the brake disc 51a; a voltage apply means 75 for applying voltage to between the electrodes 71 and 511; and a current detecting means 74 for detecting current generated by bringing the electrodes 71, 511 into contact with each other to form a turned-on state when the piston 53 arrives at the brake disc 51a, and a detected signal is considered as the detected current. |
