Figure 30-3. Torsion Bar.
Section II. SOLID AXLE SUSPENSION SYSTEMS
shaft (drive shaft) is employed with two universal joints
30-3. Purpose. The axle of the suspension is a cross
and a slip joint, as shown in figure 30-4. The torque
support on which the wheels turn. Axles that provide
reaction, drive thrust, and alinement of the axle housings
only support for the vehicle weight are called dead axles.
are resisted by the suspension springs.
Those that also incorporate means for driving the wheel
are called live axles. The term live axle applies to the
The suspension springs are pivoted on brackets at their
entire axle assembly, which consists of the housing that
forward ends and shackled to the frame at their rear
contains the drive gears, differential, and power
The rear spring brackets are the point of
transmitting shafts. Until recently, wheeled mili- tary
application of the driving thrust to the frame. Because
vehicles have employed the solid axle suspension, both
the suspension springs must resist the torque reaction of
front and rear, almost exclusively. This is because of the
the drive, stiffer springs are required than are used with
basic ruggedness, low manufacturing cost, and wide use
some of the other live axle suspensions. In addition,
on heavy commercial vehicles of the solid axle
because the springs must transmit the driving thrust,
they must be fairly flat. Because of these torque and
force transmission requirements, the Hotchkiss drive has
30-4. Live Axle Suspension.
a. The Hotchkiss drive is the conventional front and
rear live axle suspension that once was used exclusively
in American military vehicles. In this drive, a propeller
Figure 30-4. Hotchkiss Drive.