Shift Components and Function
The purpose of a disconnect-design power transfer unit is to disconnect all spinning components except for the input and intermediate drive shafts when in FWD mode. In AWD mode, engagement and disengagement of the rear propeller shaft is achieved via an internally splined, sliding shift sleeve. The axially sliding shift sleeve operates similar to a manual transmission selector sleeve.
The input shaft (2) is driven by the transmission carrier and is rotating when the vehicle is moving. The input disconnect shaft (1) is not rotating in disconnect/FWD mode. When in disconnect/FWD mode, the shift collar (3) internal splines are only engaged to the spinning input shaft (2). When AWD mode is required, the collar slides axially to couple the OD teeth of both the input shaft (2) and input disconnect shaft (1), locking the rotation of both shafts together. The sliding collar is moved using a linear and rotary cam system. With the shafts coupled, the rear propeller shaft is rotated to achieve AWD mode.
In FWD mode, the actuator motor has not been commanded to rotate the worm gear (1) and rotary cam. The ID teeth of the shift sleeve (4) are engaged only to the OD teeth of the rotating input shaft (2). The shift sleeve ID teeth are NOT engaged to the non-rotating OD teeth of the input disconnect shaft (3).
In AWD mode, the actuator motor has been commanded to rotate the worm gear (1) and rotary cam. As the rotary cam rotates, the lugs (6) of the rotary and linear cam (2) are positioned to move the shift sleeve (3) axially. The ID teeth of the shift sleeve are now engaged to the OD teeth of both the input shaft (4) and input disconnect shaft (5). This action couples the two shafts to rotate together. With the input disconnect shaft now rotating, power is transferred to the idler gear shaft and rear output shaft which in turn rotate the propeller shaft sending power to the rear drive module.