Four wheel drive system

Claim 1

A full-time four wheel drive system comprising: a transverse engine having a crankshaft; a transaxle case having a side where it is attached to said engine; a transfer case attached to said transaxle casing on said side thereof; a speed change mechanism disposed within said transaxle case and having an input shaft in axial alignment with said crankshaft and an output shaft in parallel with said input shaft; a final reduction gearing disposed within said transaxle case and having an input portion drivingly connected to said output shaft of said speed change mechanism and an output portion; a planetary gear type center differential disposed within said transfer case and having an internal gear, a sun gear, a plurality of pinion gears meshing with said internal gear and said sun gear and a pinion carrier rotatably carrying thereon said pinion gears; a viscous clutch interposed between said internal gear and said sun gear for controlling operation of said center differential; a first hollow shaft interconnecting said output portion of said final reduction gearing and said pinion carrier of said center differential; a terminal differential for a pair of left and right road wheels; a second hollow shaft passing through said first hollow shaft to interconnect one of said internal gear and said sun gear and said terminal differential; a speed-up mechanism disposed within said transfer case and having an input portion connected to the other of said internal gear and said sun gear and an output portion; a propeller shaft elongated in the direction intersecting said crankshaft at right angles; and a direction changing mechanism disposed within said transfer case and interconnecting said output portion of said speed-up mechanism and an end of said propeller shaft.