Patent ID: 7175559

Claim:
A motor vehicle, comprising: a powertrain operable for generating drive torque; a primary driveline for transmitting drive torque from said powertrain to first and second primary wheels; a secondary driveline for selectively transmitting drive torque from said powertrain to first and second secondary wheels, said secondary driveline including an input shaft driven by said powertrain, a first axleshaft driving said first secondary wheel, a second axleshaft driving said second secondary wheel, and a drive mechanism coupling said input shaft to said first and second axleshafts, said drive mechanism including a differential, a speed changing unit, and first and second mode clutches, said differential having an input component driven by said input shaft, a first output component driving said first axleshaft and a second output component driving said second axleshaft, said speed changing unit having a transfer shaft driven by said second axleshaft and first and second gearsets driven by said first axleshaft, said first mode clutch is operable for selectively coupling said first gearset to said transfer shaft for decreasing the rotary speed of said second axleshaft, and said second mode clutch is operable for selectively coupling said second gearset to said transfer shaft for increasing the rotary speed of said second axleshaft; and a control system for controlling actuation of said first and second mode clutches.