Q2. The movement of the rear axle assembly also causes the distance between the rear axle and transmission to change. (T/F)

Q3. When is a center support bearing needed and why?

Q4. Grinding or squeaking from the drive shaft is frequently caused by ___________________

Q5. How do you check for worn universal joints?

Q6. If a universal joint fails to press together with normal force, it is possible that one of the needle bearings has fallen out of place. (T/F)

DIFFERENTIALS

Learning Objective: Identify differential design variations. Describe the principles of the limited slip differential. Explain basic service and repair of a differential. Explain the adjustment of the ring and pinion gears.

Another important unit in the power train is the differential, which is driven by the final drive. The differential is located between the axles and permits one axle to turn at a different speed from that of the other. The variations in axle speed are necessary when a vehicle rounds a corner or travels over uneven ground. At the same time, the differential transmits engine torque to the drive axles. The drive axles are on a rotational axis that is 90 degrees different than the rotational axis of the drive shaft.

DIFFERENTIAL CONSTRUCTION

A differential assembly uses drive shaft rotation to transfer power to the axle shafts. The term differential can be remembered by thinking of the words different and axle. The differential must be capable ofproviding torque to both axles, even when they are turning at different speeds. The differential assembly is constructed from the following: the differential carrier, the differential case, the pinion gear, the ring gear, and the spider gears (fig. 5-12).

Differential Carrier

The differential carrier provides a mounting place for the pinion gear, the differential case, and other differential components. There are two types of differential carriers: the removable type and the integral (unitized) type.

REMOVABLE TYPE - a carrier that bolts to the front of the axle housing. Stud bolts are installed in the housing to provide proper carrier

Figure 5-12. - Conventional differential.

alignment. A gasket is installed between the carrier and the housing to prevent leakage.

INTEGRAL TYPE - a carrier that is constructed as part of the axle housing. A stamped metal or cast aluminum cover bolts to the rear of the carrier for inspection of the gears.

Differential Case

The differential case holds the ring gear, the spider gears, and the inner ends of the axles. It mounts and rotates in the carrier. Case bearings fit between the outer ends of the differential case and the carrier.

Pinion Gear

The pinion gear turns the ring gear when the drive shaft is rotating. The outer end of the pinion gear is splined to the rear U-joint companion flange or yoke. The inner end of the pinion gear meshes with the teeth on the ring gear.

The pinion gear is mounted on tapered roller bearings that allow the pinion gear to move freely on the carrier. Either a crushable sleeve or shims are used to preload the pinion gear bearings. Some differentials use a pinion pilot bearing that supports the extreme inner end of the pinion gear. The pinion pilot bearing assists the tapered roller bearings in supporting the pinion gear during periods of heavy loads.

Ring Gear

The pinion gear drives the ring gear. It is bolted securely to the differential case and has more teeth than the pinion gear. The ring gear transfers rotating power through an angle change or 90 degrees.