Final Drive Final Drive (1) Axle shaft (2) Hub (3) Drive wheel (4) spindle The power transfer group turns axle shaft (1). The gear teeth on the end of axle shaft (1) engage the gear teeth of hub (2). The gear teeth of hub (2) are on the inside diameter of the hub, which causes the rotation of the hub to be the same as the axle shafts. The reduction in size between the axle shaft and the hub causes the hub to turn at a slower speed. Spindle (4) is fastened to the truck frame and is used as a support for hub (2). Drive wheel (3) is fastened to hub (2) and turns with the hub. The final drive is a grease lubricated unit. Power Train Systems Operation 8