Abstract: A four-wheel-drive-vehicle driving force distribution apparatus has an auxiliary transmission mechanism for switching motive power transmitted to an input shaft at least between two levels, a high speed and a low speed, and transmitting the motive power to a main output shaft; a friction clutch for selectively transmitting the motive power of the main output shaft to an auxiliary output shaft; a ball cam mechanism for changing the pressing force of the friction clutch in a non-step manner; and a shift mechanism for shifting the auxiliary transmission mechanism. A clutch control mechanism is provided between a drive member fixed to an output shaft of a motor and a pinion gear and changes the clutch pressing force caused by the ball cam mechanism corresponding to clockwise rotation of the drive member performed by a motor starting from a control starting point.

Abstract: A four-wheel-drive-vehicle driving force distribution apparatus has an auxiliary transmission mechanism for switching motive power transmitted to an input shaft at least between two levels, a high speed and a low speed, and transmitting the motive power to a main output shaft; a friction clutch for selectively transmitting the motive power of the main output shaft to an auxiliary output shaft; a ball cam mechanism for changing the pressing force of the friction clutch in a non-step manner; and a shift mechanism for shifting the auxiliary transmission mechanism. A clutch control mechanism is provided between a drive member fixed to an output shaft of a motor and a pinion gear and changes the clutch pressing force caused by the ball cam mechanism corresponding to clockwise rotation of the drive member performed by a motor starting from a control starting point.

Abstract: The present invention provides a driving force distributing apparatus which can instantaneously reduce clutch pressure to thereby carry out proper operation of an ABS even if the ABS is actuated in traveling in a 4WD mode. In order to reduce pressure in a piston chamber, a control circuit drives a motor for reverse rotation. As a result, a pressure difference between a piston chamber side pressure and a pump side pressure in a supply path becomes large, pressure oil on a piston chamber side in the supply path is instantaneously discharged to an outside from a releasing hole of a quick open valve, and the pressure in the piston chamber reduces instantaneously.

Abstract: The present invention provides a driving force distributing apparatus which can instantaneously reduce clutch pressure to thereby carry out proper operation of an ABS even if the ABS is actuated in traveling in a 4WD mode. In order to reduce pressure in a piston chamber, a control circuit drives a motor for reverse rotation. As a result, a pressure difference between a piston chamber side pressure and a pump side pressure in a supply path becomes large, pressure oil on a piston chamber side in the supply path is instantaneously discharged to an outside from a releasing hole of a quick open valve, and the pressure in the piston chamber reduces instantaneously.