Transmission for four-wheel drive vehicles

The transmission for a four-wheel drive vehicle having an engine and front and rear drivelines, said transmission comprising:

• an input shaft driven by the engine about a first rotary axis;
• a transfer shaft supported for rotation about a second rotary axis;
• a tubular mainshaft rotatably supported on said transfer shaft;
• a plurality of constant-mesh gearsets each having an input gear fixed to said input shaft and a speed gear rotatably supported on said mainshaft;
• a plurality of synchronizer clutches for selectively coupling one of said speed gears to said mainshaft for driving said mainshaft at a predetermined speed ratio relative to said input shaft so as to establish a plurality of forward and reverse gears;
• a quill shaft rotatably supported on said transfer shaft adjacent to said mainshaft;
• a gear reduction unit having an input member driven by said mainshaft and an output member driven at a reduced speed ratio relative to said input member;
• a range clutch for selectively coupling said quill shaft to either of said mainshaft whereat a direct speed ratio drive connection is established or said output member of said gear reduction unit whereat said reduced speed ratio drive connection is established;
• a rear output shaft adapted for connection to the rear driveline and which is commonly aligned with said transfer shaft for rotation about said second rotary axis;
• a front output shaft adapted for connection to the front driveline and which is supported for rotation about a third rotary axis;
• a transfer mechanism connecting said front output shaft for common rotation with said transfer shaft;
• and
• an interaxle differential for permitting speed differentiation between said rear output shaft and said transfer shaft, said interaxle differential including a first sun gear fixed for rotation with said transfer shaft, a second sun gear fixed for rotation with said rear output shaft, and a planetary carrier fixed for rotation with said quill shaft and which rotatably supports planet gear means that mesh with said first and second sun gears.