Transfer Case: Notes
The transfer case is an On-Demand All Wheel Drive (AWD) system with compact chain and sprocket arrangement which provides a compact and low weight design.
The transfer case is mounted on the rear of the transmission housing and includes a multi-plate wet clutch, with electro-hydraulic actuation. It is controlled by the Transfer Case Control Module (TCCM), which automatically controls the amount of torque being transmitted to the rear and front axles.
The TCCM monitors inputs from many of the vehicle's systems including the Electronic Traction Control (ETC) and Anti-lock Brake (ABS) systems; these inputs include:
- wheel speed
- steering wheel angle
- yaw rate
- torque supplied by the engine
- position of the acceleration pedal.
Using these inputs the TCCM calculates and delivers an output to the electro-hydraulic actuator. The actuator in turn, provides pressure to the multi-plate clutch to distribute the required torque between the front and rear axles.
The system provides continuously variable response within 165 milliseconds, with high torque accuracy to provide exceptional dynamic performance.
The transfer case also improves fuel economy by providing only the requested amount of torque to the front axle. If necessary, full locking torque is available at any given time and vehicle speed, depending on road conditions and vehicle load distribution.
The transfer case incorporates a pump-less lubrication system with active sump management. The pump-less lubrication system comprises a lower sump and an upper sump. The drive chain that transfers torque to the front axle also transfers oil from the lower sump to upper sump. Oil in the upper sump lubricates the clutch pack, bearing and upper seal.
In addition to the omission of an oil pump, the active sump management system also has the added benefit of also enhancing fuel economy by reducing drag losses in the transfer case.
The transfer case has a drain plug and a level plug.