controlled manually or automatically. The differential
lock locks one axle shaft to the differential case and
bevel drive gear, forming a rigid connection between
the two axle shafts that makes both wheels rotate at the
Axles are classified as either live or dead. The live
axle is used to transmit power. The dead axle supports
part of the vehicle weight but does not drive the wheels.
The wheels rotate on the ends of the dead axle.
On rear wheel drive passenger cars, the front axle is
a dead axle, and the rear 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.
Thee third axle, part of a bogie drive, is joined to the
rearmost axle by a trunnion axle, as shown in figure
2-17. The trunnion axle is attached rigidly to the frame.
Figure 2-17.Bogie drive.
Figure 2-18.Four-wheel drive transmission.