Differential Assembly: Description and Operation

REAR DRIVE MODULE (RDM) UNIT
The rear drive module (RDM) in this vehicle consists of an aluminum housing which contains a gerotor fluid pump, clutch pack and a differential. It has a common fluid reservoir.
The on-demand rear differential distributes variable torque/power to the rear wheels via individual axle shafts.
The on-demand system operates as follows: only when front wheel slippage is encountered torque/power is proportioned to the rear wheels. As long as there is no front-to-rear speed difference; there is no torque/power to the rear wheels.
When front-to-rear wheel slippage does occur, the rear differential (gerotor) pumps fluid stored in the sump to a piston which actuates a clutch pack, which then distributes torque/power to the rear wheels.
This is an integral protection device that reduces rear wheel torque when excessive heat is generated, thus protecting the rear drive module (RDM).