Torque transmission device of a four-wheel drive vehicle

摘要

A torque transmission device of a four-wheel drive vehicle having a pair of drive shafts includes a hydraulic pump for transmitting torque to both drive shafts through a variable oil pressure generated therein according to the difference in rotational speed between both drive shafts, and a multiple disc clutch for transmitting torque to both drive shafts by a frictional coupling power. The hydraulic pump has a casing and a rotor housed therein. The casing is rotated by one of the drive shafts. The rotor is rotated by the other drive shaft through a transmitting member, a hydraulic piston mechanism and a rotary sleeve. The transmitting member has a clutch operating portion for operating the clutch. When the transmitted torque exceeds a predetermined level, the hydraulic piston mechanism is adapted to move the transmitting member to operate the multiple disc clutch with no intermediary of the casing.