Four-wheel vehicle drive system

摘要

A four-wheel vehicle drive system comprising a power unit having an output shaft in a lateral direction of the vehicle; a transmission gear unit having input and output shafts parallel with an extension of the axis of rotation of the output shaft of the power unit; a power transfer gear rotatable about an axis parallel with the transmission input and output shafts and driven by the transmission output shaft; a first wheel drive unit comprising a differential gear assembly for one first pair of road wheels and a planetary gear assembly having a first rotary member driven by the transfer gear, a second rotary member driving the differential gear assembly and a third rotary member; low-and-high speed shifting clutch means to provide coupling selectively between the power transfer gear and the third rotary member and between the third rotary member and a stationary member fixed in the vehicle; a second wheel drive unit wherein the driving power transmitted to the second rotary member is split into two components, one of which is carried to the differential gear assembly and the other of which is carried to a driven gear rotatable about an axis in a fore-and-aft direction of the vehicle; a driveline intervening between the driven gear and another pair of road wheels; and two-wheel/four-wheel drive shifting means intervening between the driven gear and the driveline.