This is scanned directly from "The Autocar Handbook- Complete Guide to
the Modern Car" Twenty Third Edition Author: JR Singham Copyright
1969
Hope it answers your questions!
The Rear Axle
Except when independent rear suspension is used, the rear axle, rear
wheels and crown wheel and pinion form an integral unit attached to the
car through a pair of leaf springs. The unit derives its strength from
the axle housing which consists of a central box containing the crown
wheel and pinion and two tubular extensions for supporting the wheels
and shafts. The "live" part of the axle, that is the shaft linking the
crown wheel to the wheels, transmits torque and does not carry any
appreciable weight. Because of the need for differential wheel speed,
the shaft is in two halves. Serving a limited purpose as it does, each
half-shaft is quite small in diameter. The whole axle assembly is often
referred to as a "live axle ".
The bearing arrangement shown in Fig. 12.9 is for a "semi-floating"
axle. The "semi" indicates that the shaft has to carry weight as well
as torque; this is because the wheel is bolted directly to the
half-shaft flange. On a "fully floating" axle, the wheel is bolted to a
hub which runs on bearings attached only to the axle housing. The
half-shafts are splined into the wheel hubs so that the connection is a
sliding one and torque alone can be transmitted. This arrangement eases
the task both of the half-shafts and of the bearings. The second
arrangement shown in Fig. 12.9 is for a "three-quarter floating axle".
In this case the wheel is bolted to a hub and to the half-shaft flange.
Most of the weight is carried through the hub though a small amount can
be taken through the half shafts to the inner bearings adjacent to the
crown wheel.
John Greenwood Jacksonville, Florida
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