| 摘要 |
PROBLEM TO BE SOLVED: To make judgement at a stage before proceeding to a speed changing process for preventing the double engagement of friction engagement elements resulting from the malfunction of a hydraulic control valve for controlling an engagement hydraulic pressure for the friction engagement elements to be released for speed change. SOLUTION: This control device 16 operates a selector valve 15 when a preset time passes since determining that speed change is required, so that the output hydraulic pressure of the hydraulic control valve 13 or 14 is lowered from the same hydraulic pressure value as that for a line hydraulic pressure PL to an upper limit value in a controlled hydraulic pressure range PC1 or PC2. Reaction switches 17a, 17b are set for outputs to be changed when the output hydraulic pressure of the control valve is lowered from the line hydraulic pressure to a set hydraulic pressure value or lower which is higher than the upper limit value in the controlled hydraulic pressure range. The control device does not proceed to execute a speed changing process unless the outputs of the reaction switches are changed within a preset time since executing the operation of the selector valve.
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