Patent ID: 7214158

Claim:
A drive mechanism used in a four wheel drive transverse engine-mounted vehicle to transmit drive force of an engine from a transmission to front wheels and rear wheels, the drive mechanism comprising: a differential unit comprising: a rotatable case; a ring gear fixed to the case, the ring gear meshing with an output gear of the transmission; an axle shaft mounted within the case, to which drive force from the ring gear is transmitted, and which transmits the drive force to the front wheels; and a drive gear fixed to a plurality of boss portions formed in the case and disposed spaced apart from the ring gear in an axial direction of the axle shaft; a transfer unit disposed rearward of the differential unit and comprising a driven gear that meshes with the drive gear; a propeller shaft to which drive force from the driven gear is transmitted and which transmits the drive force to the rear wheels; a first material-removed portion made of a concave portion and formed in an inner circumference of a portion to which the axle shaft of the case is mounted; and a second material-removed portion made of a concave portion and extending in the axial direction of the axle shaft, the second material-removed portion being formed between each of the plurality of boss portions.