Power transfer device for four-wheel drive

Claim 1

A power transfer device for four-wheel drive in combination with a power transmission, comprising: a first differential of the bevel gear type arranged to split the driving torque from said power transmission into two torque delivery paths respectively for front-wheel drive and rear-wheel drive; a second differential of the bevel gear type arranged coaxially with said first differential at one side thereof to transfer the split driving torque from a first side gear of said first differential to one of front and rear-wheel axles; an output gear arranged coaxially with said first differential at the other side thereof to transfer the split driving torque from a second side gear of said first differential to the other of said rear and front-wheel axles; and a limited-slip differential assembled within a mounting case for said output gear to effect limited-slip torque proportional to the difference in rotational speed between said side gears; wherein said limited-slip differential includes first and second rotary elements coupled with each other for relative rotation, said first rotary element being assembled within said mounting case for relative rotation and having a hollow shaft portion aligned with a first hollow shaft which is drivingly connected to the second side gear of said first differential, and said second rotary element being mounted on a second hollow shaft which is drivingly connected at an inner end thereof to the first side gear of said first differential and extends into the interior of said mounting case through said first hollow shaft, and a clutch sleeve arranged between said first differential and said output gear and axially slidably mounted on said first hollow shaft for rotation therewith and being shiftable between a first position where it is engaged with said mounting case and said hollow shaft portion of said first rotary element and a second position where it is disengaged from said mounting case and said hollow shaft portion of said first rotary element and engaged with a casing of said first differential, whereby said power transfer device may be switched between limited slip four wheel drive when said clutch sleeve is in said first position, and two wheel drive when said clutch sleeve is in said second position.