| 摘要 |
The transfer case of a vehicle that can be driven in two-wheel drive or four-wheel drive includes a range speed transmission driveably connected to the output of a multiple speed ratio transmission and adapted to drive the transfer case output shaft. A drive sprocket journalled on the output case is driveably connected by a chain belt to a driven sprocket that is connected to the front driveshaft. The front axle has a differential that transmits power from the front driveshaft to left and right axleshafts when four-wheel drive is selected. Automatic locking hubs driveably connect the front axleshafts to the front wheel assemblies and are adapted to automatically disengage when the front wheels rotate opposite the direction that produced engagement of the locking hubs. The drive sprocket is accelerated from rest to the speed of the output shaft of the transfer case through operation of a magnetic clutch or hydraulic coupling. A hub member engaged with the driven sprocket is moved to a position of potential engagement with the spline teeth on the output shaft when four-wheel drive operation is selected. The splines remain disengaged, however, until the speed of the drive sprocket reaches approximately that of the output shaft; then the splines engage and the sprocket is driven from the output shaft.
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