Differential Assembly: Description and Operation
These vehicles use various rear axles. The axles can be identified by the ring gear size in inches, by the ring gear size in inches manufacturer (American Axle Manufacturing or Dana) and by the type of axle shaft used (semi-floating or full-floating). American Axle Manufacturing supplies the 8 5/8, 9 1/2, and 10 1/2 inch ring gear axle. The locking differential is supplied by Eaton.
The driveline components in this vehicle have been system balanced at the factory. System balance provides for a smoother running driveline. These components include the propeller shafts, drive axles, pinion shafts and output shafts. Affixed to the rear axle is a system balanced driveline notice indicating that the drive line components have been factory tested.
All components must be referenced marked before disassembly and reassembled in the exact relationship to each other the components had before removal.
REAR AXLE OPERATION
A differential has two side gears and two pinion gears. Some differentials have more than two pinion gears. Each side gear is splined to an axle shaft; so each axle shaft must turn when its side gear rotates.
The pinion gears are mounted on a shaft, and are free to rotate on this shaft. The pinion shaft is fitted into a bore in the differential case and is at right angles to the axle shafts.
Power is transmitted through the differential as follows: the drive pinion rotates the ring gear. The ring gear, being bolted to the differential case, rotates the case components. The differential pinion, as it rotates with the case components, forces the pinion gears against the side gears. When both wheels have equal traction, the pinion gears do not rotate on the pinion shaft because the input force on the pinion gear is equally divided between the two side gears. Therefore, the pinion gears revolve with the pinion shaft, but do not rotate around the shaft itself. The side gears, being splined to the axle shafts and in mesh with the pinion gears, rotate the axle shafts.
The differential allows the wheels to turn at different rates of speed while the axle continues to transmit the driving force. This prevents premature wear on internal axle parts and tire scuffing when the vehicle is turning.
LOCKING DIFFERENTIAL OPERATION
The locking rear differential allows for normal differential function as indicated in the standard rear axle description. Additionally, the locking rear differential uses multi-disc clutch packs and a speed sensitive engagement mechanism that locks both wheels together if one wheel should spin excessively during slow vehicle operation.
The controlled slipping characteristic at higher torque enables the vehicle to negotiate turns in a normal manner. Resistance to slippage at lower torques enables the vehicle to maintain traction even if the other wheel begins to spin.
Full locking is accomplished through the use of a heavyweight governor mechanism, cam system, and multi-disc clutch packs. The flyweights on the governor mechanism move outward to engage a latching bracket whenever the wheel-to-wheel speed varies by approximately 160 km/h (100 mph) or more. This action retards a cam which, in turn, compresses the multi-disc clutch packs, locking both side gears to the case. The 160 km/h (100 mph) wheel-to-wheel speed allows for cornering without differential lockup. At vehicle speeds above approximately 32 km/h (20 mph), the latching bracket overcomes a spring preload and swings away from the flyweights.
At this vehicle speed or greater, the differential will not to lock, since the added traction is generally not required. All gear axle parts of the vehicle equipped with the locking rear axle are interchangeable with those equipped with the conventional rear axle, except for the case assembly.