Live Axle Configurations.

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Figure 29-9. Worm Gear Drive.

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TM-9-8000 Principles of Automotive Vehicles Manual

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Figure 29-11. Axle Configurations.

TM 9-8000

c. Hypoid (Fig. 29-10). Hypoid gearing has come

axle shafts are supported in the housing by roller

bearings at the center and outer ends. The rear wheels

into rather extensive use recently, mainly for passenger

are keyed on tapers at the outer ends of the axle shafts

cars. A portion of a hypoid rear axle is shown in figure

and held by castle nuts and cotter pins. In addition to

29-10. This rear axle is almost the same as the spiral-

turning the wheels, the rotating axle shafts carry the

bevel gear rear axle, except that the drive pinion and

entire weight of the rear of the vehicle on their outer

bevel drive gear are cut with a somewhat different tooth

ends. All stresses caused by turning corners, skidding,

form, which permits the drive pinion to mesh with the

or by wobbling wheels are taken by the axle shafts. The

bevel drive gear below the center of the latter. This

differential side gears are keyed on the inner ends of the

construction allows the propeller shaft to be lowered and

axle shafts, which carry the weight of the differential

sometimes makes a shaft tunnel in the floor of the rear

case. The stresses created by the operation of the

compartment of the vehicle unnecessary. Due to their

differential are taken by the axle shafts. Side thrust on

design, hypoid gears operate under extremely high tooth

the axle shafts is taken care of by the roller bearings,

pressure and require a special hypoid lubricant.

and ball bearings are provided at each side of the

differential case to take care of end thrust. This type of

29-10. Live Axle Configurations.

rear axle is obsolete now.

a. General. A live axle is one that supports part of

Semifloating (B, Fig. 29-11). The semi-floating

the weight of a vehicle and also drives the wheels

rear axle is used on most passenger and light

connected to it. The term is applied to the entire

commercial vehicles. The principal difference between it

assembly, which consists of a housing containing a bevel

and the plain live axle is In the manner of supporting the

drive pinion, bevel drive gear differential and axle shafts

differential assembly. In the plain live axle, the differential

together with their bearings, and sometimes additional

case Is carried on the Inner ends of the axle shafts. In

mechanisms. The term live axle is opposed to the term

the semifloating axle, it is carried by bearings mounted in

dead axle. A dead axle is one that carries part of the

the differential carrier. The axle shafts are splined to the

weight of a vehicle but does not drive the wheels. The

differential side gears. This relieves the axle shafts of the

wheels rotate on the ends of the dead axle. The usual

weight of the differential and the stresses caused by its

front axle of a passenger car is a dead axle and the rear

operation that are taken by the axle housing. The Inner

axle is a live axle. In four wheel drive vehicles, both front

and rear axles are live axles, and in six-wheel drive

vehicles all three axles are live axles.

b. Plain (A, Fig.

29-11).

The plain, or

nonfloating, rear axle was one of the first used. In it, the

Figure 29-10. Hypoid Gear Drive.

29-10