| 摘要 |
An automatic power shift transfer case for a four wheel drive vehicle has a front high-low range planetary gear set and a rear differential planetary gear set aligned symmetrically about the transfer case central shaft axis. The front and rear planetary gear sets are arranged in a back-to-back substantially mirror image manner so as to share a common carrier interposed therebetween. The front planetary gear set with either its low or high range clutch applied selectively delivers a corresponding speed through the common carrier to the rear planetary gear set. The torque flow is split in a predetermined manner wherein a minimum torque to maximum may be selectively delivered to the rear axle, via a rear planetary gear set modulating clutch while the remaining torque is normally delivered to the front axle. Lock-up of the modulating clutch allows the front axle to be disconnected providing a two-wheel drive mode.
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