housing, depending on the particular manufacturer’s design.
In Figure 16-36C, notice the use of the tapered axle.
This is one of two methods used to secure a wheel hub to
its axle. The tapered end wedges into a tapered hole in the
wheel hub, and the key keeps the axle from rotating in the
hub. The other method, mentioned earlier, has the wheel
hub (axle flange, in this case) solidly mounted to the axle.
The design of the semi-floating axle causes weight
loads to be placed on the axle. These loads will shift as the
axle rotates, placing flexing stresses on the shaft. On auto-
mobiles and light trucks, the loading is not serious and the
axles will usually last the life of the vehicle.
Full-floating axles
If the rear end will be subjected to heavy loads, such
as the rear end of a large truck might be, a full-floating axle
is used. Figure 16-37 shows an example of a full-floating
axle. With this design, the axle drives the wheel but does
not carry any of the vehicle weight. The weight passes
through the bearings on the wheel hub. The wheel hub
absorbs the stresses. This design reduces the stresses on
the shaft, prolonging its life. Full-floating axles are not
used on light duty vehicles because of their extra cost and
complexity.
Independently Suspended Drive Axle
Independently suspended drive axles, used on
vehicles with independent rear suspension, resemble
miniature drive shaft assemblies. The axle consists of a
central shaft with flexible joints and stub axles on each
end. The flexible joints—either cross and roller U-joints or
Chapter 16 Rear Axle Assembly Construction and Operation 329
Axle
flange
Axle retainer
plate
Brake backing plate
Seal
Axle
collar
Axle
supports
and drives
wheel
Axle seal
Real axle
housing
Axle bearing
Retainer-to-
housing bolt
Wheel
lug stud
Axle
bearing
Rear axle housing
Brake backing
plate
Drive axle
Gear oil
Axle
housing
seal
Axle flange
Rear axle housing
Brake backing plate
Ring seal
Key Washer
Nut
Outer
retainer
plate
Tapered axle
supports wheel
hub and
drives wheel
Axle seal
Axle bearing Bolt
Washer
Endplay adjusting
axle shims
C—Tapered
roller bearing semi-floating axle. The bearing preload is
adjusted by shims or an adjusting nut. The axle is retained in same
manner as ball bearing, except without the axle collar. The shoulder
on the axle keeps the axle from sliding past the bearing.
A—Ball
bearing semi-floating axle. The ball bearing is retained on
shaft by a pressed on axle collar. The bearing and axle are held in
the housing by a bolted retainer plate.
B—Roller
bearing semi-floating axle. The major difference between this
design and that of ball bearing is the shaft locking method. This axle is
retained by a C-lock at the inside of the shaft. The C-lock attaches axle
to the differential. The bearing plays no part in keeping the shaft in place.
Figure 16-36. The semi-floating axle is the most common shaft
and bearing design used on cars and light trucks. The bearing
passes the vehicle weight through the axle shaft and out to the
wheel. The axle drives and supports the vehicle.
(Fiat, General Motors, Deere & Co.)
Axle
bearing
Drive wheel
Hub, not axle, supports
weight of car
Axle bearing
Drive
axle
Axle
housing
Wheel hub supported
by bearings on
axle housing
Wheel hub
Sleeve nuts
retain bearing
Figure 16-37. The full-floating axle is used on trucks and other
vehicles that carry heavy loads. Bearings on the hub transmit
the vehicle weight from the rear axle housing to the wheel hub
and the wheel without the loading axle. The only job of the axle
is to propel the vehicle. (Deere & Co.)