Compact power transmission device for a four-wheel drive vehicle

Claim 1

A power transmission device for a four-wheel drive vehicle having a compact transfer unit including front wheel differential gear means, differential motion limiting mechanism means and center differential gear means, comprising; a first gear mount casing having a gear adapted to mesh with an output of an automatic transmission; a front wheel differential gear arranged in said first gear mount casing, and including a diff-carrier having a pinion adapted to mesh with right and left side gears coupled to right and left front axles; a differential motion limiting mechanism arranged coaxially with said front wheel differential gear in said first gear mount casing, said differential motion limiting mechanism including a cluth for connecting or disconnecting said first gear mount casing and said diff-carrier; a second gear mount casing disposed coaxially with respect to said first gear mount casing; and a center differential gear arranged in said second gear mount casing, and including a diff-carrier coupled with said first gear mount casing, a first side gear coupled with the diff-carrier of said front wheel differential gear, and a second side gear coupled with said second gear mount casing adapted for transmitting power to rear wheels of the four-wheel drive vehicle; wherein the diff-carrier of said center differential gear is supported between said first side gear and said second gear mount casing and has an extremity having an open end not supported by said second side gear, and said second side gear is connected directly to said second gear mount casing.