Rear Axle - 9 1/4

DESCRIPTION








The 9 1/4 Inch axle housings consist of a cast iron center section with axle tubes extending from either side. The tubes are pressed into and welded to the differential housing to form a one-piece axle housing (Fig. 1).
The axles have a vent hose to relieve internal pressure caused by lubricant vaporization and internal expansion.
The axles are equipped with semi-floating axle shafts, meaning vehicle loads are supported by the axle shaft and bearings. The axle shafts are retained by C-locks in the differential side gears.
The removable, stamped steel cover provides a means for inspection and service without removing the complete axle from the vehicle.
The axle has a date tag and a gear ratio tag. The tags are attached to the differential housing by a cover bolt.
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 is a one-piece design. The differential pinion shaft is retained with a screw. Differential bearing preload and ring gear backlash are set and maintained by threaded adjusters at the outside of the differential housing. Pinion bearing preload is set and maintained by the use of a collapsible spacer.
Axles equipped with a Trac-Lok differential are optional. A differential has a one-piece differential case, and the same internal components as a standard differential, plus two clutch disc packs.

AXLE IDENTIFICATION





The axle differential cover can be used for identification of the axle (Fig. 2). A ratio tag is attached to the top of the differential cover.

OPERATION
The axle receives power from the transmission/ transfer case through the rear propeller shaft. The rear propeller shaft is connected to the drive pinion 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 differential pinions and side gears. The side gears are splined to the axle shafts.

STANDARD DIFFERENTIAL





During straight-ahead driving, the differential pinion gears do not rotate on the pinion shaft. This occurs because input torque applied to the gears is divided and distributed equally between the two side gears. As a result, the differential pinion gears revolve with the pinion shaft but do not rotate around it (Fig. 3).





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. 4). In this instance, the input torque applied to the differential pinions is not divided equally. The differential pinions now rotate around the pinion shaft in opposite directions. This allows the side gears and axle shaft attached to the outside wheel to rotate at a faster speed.

TRAC-LOK 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. 5).
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.