Transfer Case
| ITEM | DESCRIPTION |
|---|---|
| 1 | Front driveshaft output flange |
| 2 | Oil baffle |
| 3 | Intermediate gear |
| 4 | Actuator worm drive gear |
| 5 | Front drive gear |
| 6 | Multiplate clutch assembly |
| 7 | Ball ramp assembly |
| 8 | Input shaft |
| 9 | Rear driveshaft output flange |
| 10 | Mounting bush |
| 11 | Transfer Case Control Module (TCCM) |
| 12 | Front output drive gear |
The transfer case includes a multi-plate wet clutch, electromechanical actuation, and a gear driven front output. The system ensures high dynamic torque distribution between front and rear wheels.
The transfer case is mounted on the rear of the automatic transmission housing and is also supported on a subframe attached to the vehicle body. The subframe is attached to the vehicle body with four bolts.
A mounting bush is attached to the right side of the transfer case and is secured to the subframe. The bush, along with two snubbers, provides damping for vibrations in the driveline. A mass damper is attached to the rear of the transfer case to further improve Noise, Vibration and Harshness (NVH).
The transfer case comprises two casing halves, bolted together and sealed with a gasket. The casings house bearings in which the input shaft, intermediate gear and front output shaft run.
The input shaft passes through the two casings and is attached by a flange to the rear driveshaft. This provides 100% drive to the rear wheels only when the multiplate clutch is disengaged.
The multiplate clutch comprises an inner drive hub, an outer basket and set of drive plates and friction plates. The drive plates are located on splines on the input shaft and rotate at all time when the input shaft is rotating. The friction plates are located in grooves in the outer clutch basket which is positively attached to the front drive gear. The front drive gear and outer clutch basket are located on bearings to allow speed difference relative to the input shaft when no locking torque is applied. When the vehicle is moving, the front driveshaft, the front driveshaft output flange and output drive gear, the intermediate gear and the front drive gear and outer clutch basket all rotate. Torque is not applied to the front driveshaft until the TCCM engages the multiplate clutch.
The ball ramp assembly is located on extensions to the casings and is stationary and does not rotate with the input shaft. The ball ramp comprises two plates with opposing tapered grooves, into which a hardened steel ball is located. One of the ball ramp plates is attached to a pressure plate which acts directly on the multiplate clutch. The second plate has an annular gear ring which is driven by the worm drive of the TCCM actuator. When the second plate is rotated by the actuator and worm drive, the steel balls are forced up the tapered grooves. This causes the first plate to move axially and apply pressure to the multiplate clutch via the pressure plate. The amount of pressure applied is dependent on the rotation of the annular gear on the second plate and is controlled by the TCCM. This variable adjustment of the ball ramp allows infinite adjustment of the torque loading through the clutch and the amount of torque applied through the gears to the front output shaft flange.
The casings have a drain plug and a level plug, which allow the oil level in the unit to be checked or replaced in line with the service schedule.