Transmission for 4-wheel driving

A power transfer apparatus for transmitting power from a change-speed transmission to the driving wheels of a four-wheel drive vehicle, comprising:

• a first differential mechanism for driving the front wheels of the vehicle, said first differential mechanism having a final reduction gear which is adapted to be driven by the change-speed transmission;
• a transfer mechanism comprising a rotatable transfer shaft, first and second bearings adjacent to the opposite axial ends of said transfer shaft, respectively, for rotatably supporting said transfer shaft, a first, driven gear mounted on said transfer shaft axially inside of and close to said first bearing and adapted to drivingly connect said transfer shaft to said final reduction gear, and a second, drive bevel gear mounted on said transfer shaft axially inside of and close to said second bearing;
• a rotatable shaft adapted to drive the rear wheels of the vehicle, a transfer, bevel gear secured to said rotatable shaft and meshed with said second, drive bevel gear;
• a casing enclosing said first differential mechanism, said transfer mechanism, said rotatable shaft and said transfer bevel gear, said casing including a partition wall separating said first differential mechanism from said transfer mechanism and providing a first opening therebetween for permitting said final reduction gear to mesh with said first, driven gear, said casing and said partition wall defining a second, circular opening of large diameter encircling said transfer shaft, said second, circular opening being located axially between said first, driven gear and said second, drive bevel gear and axially between said transfer bevel gear and said first opening,
• said transfer shaft having a circular, enlarged hub disposed within said second, circular opening and substantially completely filling same,
• an annular oil seal mounted on said partition wall and said casing inside said circular opening and encircling said hub, said annular oil seal sealing said circular opening against the flow of lubricant through said circular opening.