Construction:
The ring gear (crown wheel) of the final drive is attached to a differential case which contains four bevel type gear pinions all facing inwards, meshing with each other in the form of a box. Two of the bevel pinions opposite each other are splined to the half shafts and are referred to as the sun gears. The other opposed pair of pinions are free to rotate upon a pinion shaft and are known as pinion shaft which acts as a pivot for the pinion gears in mounted in the differential housing which is driven by the ring gear. There is no direct connection between the ring gear and the half shafts.
The final drive gears must function precisely in correct relationship with each other. At the same time they will be transmitting very high torque. For this reason, the final drive and differential assembly is located in the axle casing and supported on taper roller bearings.
