Abstract: A fluid leakage preventing device incorporated in a hydraulically-operated system which includes an accumulator for storing a working fluid under pressure, an actuator operated by the fluid supplied from the accumulator, and a control valve having an open position and a closed position for fluid communication and disconnection between the accumulator and the actuator, respectively. The fluid leakage preventing device includes a fluid leakage detector for generating an output signal indicative of the leakage flow of the fluid from said accumulator through the control valve placed in the closed position. The device further includes a valve reciprocating arrangement responsive to the output signal of said fluid leakage detector, for effecting at least one reciprocating movement of a valving member of the control valve.

Abstract: A plurality of speed sensors sense rotational speeds of respective vehicle wheels including a right-hand vehicle wheel and a left-hand vehicle wheel. A speed of the right-hand vehicle wheel and a speed of the left-hand vehicle wheel are calculated on the basis of detection signals of the speed sensors. A judgment is made as to whether or not a vehicle wheel having a small tire is present in the vehicle wheels on the basis of the calculated speeds of the right-hand vehicle wheel and the left-hand vehicle wheel. In cases where a vehicle wheel having a small tire is judged to be absent, a control quantity is calculated by use of all the detection signals of the speed sensors. In cases where a vehicle wheel having a small tire is judged to be present, a control quantity is calculated by use of the detection signals of the speed sensors except the detection signal of the speed sensor of the vehicle wheel having the small tire. A controlled object is controlled in accordance with the calculated control quantity.

Abstract: A diagnostic apparatus for a continuously variable transmission the speed ratio and/or the rate of variation in the speed ratio of which are controlled by a shift-regulating device controlled by command signals from a control system.

Abstract: A continuously variable transmission (CVT) for use in a vehicle is controlled such that an actual engine speed Ne is equalized to a desired engine speed No. When a driver's request for a rapid speed change of the vehicle is addressed, a desired engine speed Ns for steady state or the desired engine speed No before the request is detected is defined as a first value Nc1. While the request continues the desired engine speed Ns for steady state which is determined by current values of vehicle running parameters is defined as a second value Nc2. The product B.multidot.(Nc2-Nc1) of a constant B and Nc2 minus Nc1 is calculated and defined as a desired engine speed during the request.