Rear Axle - 286RBI
REAR AXLE 286RBIDESCRIPTION
The Rear Beam-design Iron (RBI) axle housings consist of an iron center casting (differential housing) with axle shaft tubes extending from either side. The tubes are pressed into the differential housing and welded. The axles are full floating axle shafts, that are supported by the axle housing tubes. The full float axle shafts are retained by bolts attached to the hub.
The differential case for the standard differential is a one-piece design. Differential bearing preload and ring gear backlash are adjusted by the use of shims located between the differential bearing cones and case. Outboard protective spacers are located between the differential bearing cup and housing. Pinion bearing preload is set and maintained by the use of shims. Pinion height is controlled by a shim pack located under the inner pinion bearing cup. The differential cover provides a means for inspection and service.
Axles equipped with a Trac-Lok differential are optional. The differential contains two clutch packs, four pinion gears, and a one-piece pinion mate cross shaft to provide increased torque to the non-slipping wheel in addition to the standard differential components. A Trac-lok differential for the has a two-piece differential case.
OPERATION
STANDARD DIFFERENTIAL
The axle receives power from the transmission/ transfer case through the rear propeller shaft. The rear propeller shaft is connected to the pinion gear, which rotates the differential through the gear mesh with the ring gear bolted to the differential case. The engine power is transmitted to the axle shafts through the pinion mate and side gears. The side gears are splined to the axle shafts.
During straight-ahead driving, the differential pinion gears do not rotate on the pinion mate shaft. This occurs because input torque applied to the gears is divided and distributed equally between the two side gears. As a result, the pinion gears revolve with the pinion mate shaft but do not rotate around it (Fig. 1).
When turning corners, the outside wheel must travel a greater distance than the inside wheel to complete a turn. The difference must be compensated for to prevent the tires from scuffing and skidding through turns. To accomplish this, the differential allows the axle shafts to turn at unequal speeds (Fig. 2). In this instance, the input torque applied to the pinion gears is not divided equally. The pinion gears now rotate around the pinion mate shaft in opposite directions. This allows the side gear and axle shaft attached to the outside wheel to rotate at a faster speed.
TRAC-LOK(tm) DIFFERENTIAL
The Trac-lok clutches are engaged by two concurrent forces. The first being, the preload force exerted through Belleville spring washers within the clutch packs. The second is the separating forces generated by the side gears as torque is applied through the ring gear (Fig. 3).
The Trac-lok design provides the differential action needed for turning corners and for driving straight ahead during periods of unequal traction. When one wheel loses traction, the clutch packs transfer additional torque to the wheel having the most traction. Trac-lok differentials resist wheel spin on bumpy roads and provide more pulling power when one wheel loses traction. Pulling power is provided continuously until both wheels lose traction. If both wheels slip due to unequal traction, Trac-lok operation is normal. In extreme cases of differences of traction, the wheel with the least traction may spin.