Rear Axle Operation

Engine torque is provided by a rear propeller shaft that is bolted to the pinion gear by a universal joint and pinion flange. The pinion gear is in constant mesh with the ring gear and causes it to turn. The ring gear then rotates the differential case causing the differential pinion gears to turn with the case. This causes the side gears and both rear axle shafts to rotate. When both wheels have equal traction, the pinion gears do not rotate on the cross shaft. This is due to an input force that is equally divided between the side gears. In other words, the pinion gears revolve with the cross shaft but do not rotate around it. When the vehicle turns a corner, the outer axle must turn faster than the inner axle. When the inner axle turns slower than the outer, it slows its side gear. The differential pinion gears will roll around the slower side gear providing torque to the outer axle shaft.