STEERING SYSTEMS AND WHEEL ALINEMENT
Section I. STEERING SYSTEMS
controlled steering and because greater under-body
33-1. Steering Methods.
clearance is required for fifth-wheel steering systems.
a. Ackerman System. The ackerman system (fig.
33-2. Solid Axle Steering Linkage. The steering
33-1) is used exclusively on passenger cars and many
linkage on vehicles with a solid front suspension (fig. 33-
wheeled military vehicles. Correct ackerman steering
3) only needs to deal with the relative motion between the
during a turn requires that each wheel turn around a point
front axle and frame. For this reason the steering linkage
located on an extension of the rear axle centerline. The
is fairly simple and easily designed.
steering arms are bent slightly toward each other so that
their centerlines, if extended, would intersect in front of
a. The common solid axle suspension utilizes a
the rear axle. With the ackerman system, as the vehicle
drag link to connect the pitman arm to the steering
is making a turn, the inside wheel will turn sharper than
linkage. The drag link is made in a tubular or rod form
the outer wheel, therefore allowing all the wheels to travel
and is provided with springs to cushion shocks and
around a common point.
prevent transmission of the shocks to the steering gear.
A housing is provided on one end of the drag link to
b. Fifth Wheel. Fifth-wheel steering (fig. 33-2) is
receive the ball end of the pitman arm. Ball sockets, coil
accomplished by pivoting an entire axle around a central
springs, spring seats, and a screw plug secured by a
point. The wheels of each axle maintain their initial
cotter pin are inserted in this housing to hold the pitman
position with respect to each other and the
arm ball. Sometimes the slot in which the pitman arm is
interconnecting axle during a turn. This type of steering
inserted extends the entire length of the
commonly is applied to towed vehicles because of the
mechanical difficulties of
Figure 33-1. Ackerman Steering System.