Rear Axle - 267RBI

DESCRIPTION
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 in to form a one-piece axle housing.
The integral type housing, hypoid gear design has the centerline of the pinion set below the centerline of the ring gear.
The axles are equipped with full-floating axle shafts, meaning that loads are supported by the axle housing tubes. The full-float axle shafts are retained by bolts attached to the hub. The hub rides on two bearings at the outboard end of the axle tube. The axle shafts can be removed without disturbing or removing the wheel bearings. The wheel bearings are opposed tapered roller bearings and are contained in the hub assembly.
The removable, stamped steel cover provides a means for inspection and service without removing the complete axle from the vehicle. A small, stamped metal axle gear ratio identification tag is attached to the housing cover via one of the cover bolts. This tag also identifies the number of ring and pinion teeth.
The rear wheel anti-lock (RWAL) brake speed sensor is attached to the top, forward exterior of the differential housing. A seal is located between the sensor and the wire harness connector. The seal must be in place when the wire connector is connected to the sensor. The RWAL brake exciter ring is press-fitted onto the differential case against the ring gear flange.
The differential case for the standard differential is a one-piece design. The differential pinion mate shaft is retained with a roll pin. Differential bearing preload and ring gear backlash are adjusted by the use of shims located between the differential bearing cones and case. Pinion bearing preload is set and maintained by the use of a solid shims.
Axles equipped with a Power-Lok differential are optional. A Power-lok differential has a two-piece differential case. A Power-lok differential contains four pinion gears and a two-piece pinion mate cross shaft to provide increased torque to the non-slipping wheel through a ramping motion in addition to the standard Trac-lok components.

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 comers, 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.

POWER-LOK DIFFERENTIAL





The Power-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 Power-lok designs provide 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. The Power-lok differential additionally utilizes a ramping action supplied by the cross shafts to increase the force applied to the clutch packs to increase the torque supplied to the non-slipping wheel. Power-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, operation is normal. In extreme cases of differences of traction, the wheel with the least traction may spin.