Abstract: A control system for an automatic transmission including a hydraulic power transmission, a clutch, and a brake which is engaged to prevent a vehicle from rolling backward thereby establishing a hill-hold state in the speed change unit. The control system includes a stop state detector which detects the vehicle stopped state when the forward driving range is selected, the accelerator pedal is released and the brake pedal is depressed. The control system further includes a clutch disengaging system which provides a neutral control, and a brake engaging system which provides a hill-hold control and performs a neutral control with the engine not under a load.

Abstract: A control system for an automatic transmission includes a clutch for transmitting the rotation of a fluid transmission unit to a speed change mechanism of a transmission and a hydraulic servo for applying/releasing the clutch. A stop state detector is provided for detecting the stop state of the vehicle. A release control oil pressure changer lowers the oil pressure of the hydraulic servo by a first set pressure when the vehicle stop state is detected. An in-neutral control oil pressure changer raises the oil pressure of the hydraulic servo by a second set pressure, when the difference between the input side RPM and the output side RPM of the fluid transmission unit has not changed, and lowers the same by a third set pressure when the rotational speed difference has changed. The first set pressure is different from the second and third set pressures.

Abstract: An accumulator fluid control system for a hydraulic servo in a vehicular automatic transmission includes an accumulator having a cylinder, a piston, a return spring, a chamber disposed in the cylinder, a first and second input ports connected to a first passage, an output port connected to a second passage, and a check valve for controlling the connection between the first and second passages through the second input port.