Chapter 25 Steering Systems 503
purpose of the idler arm is to keep the center
link in alignment as it is moved by the pitman
arm. Figure 25-10 shows a common idler arm
design.
Tie Rods
Tie rods, which were discussed previously,
are used to connect the steering arms to the cen-
ter link, Figure 25-11. The parallelogram steer-
ing system has two inner tie rods and two outer
tie rods.
A threaded tie rod sleeve is installed
between the tie rods to form a tie rod assembly.
The threads on one side of the assembly are left-
hand threads, while the threads on the other
side are right-hand threads. Therefore, turning
the sleeve will change the length of the assem-
bly. Tie rod assembly length can be changed to
adjust toe. This is discussed in more detail in
Chapter 27, Wheel Alignment. One type of adjust-
able tie rod end is shown in Figure 25-12. A
typical tie rod adjustment procedure is shown
in Figure 25-13.
The tie rod assemblies on parallelogram link-
age are usually equal length and about the same
length as the lower control arms. As the frame (to
which the center link is fastened via the pitman
arm and idler arm) moves up and down in rela-
tion to the spindle, there will be minimum distur-
bance in toe-in and toe-out, since the control arm
Center link Pitman arm Steering gear
Figure 25-9.
A pitman arm on a steering gear. The pitman arm is
connected to the center link with a ball joint.
Ford
Bracket
Idler arm
Figure 25-10.
Idler arm and bracket. The main job of the idler arm is to
support the linkage on the side opposite the pitman arm.
AleksandrN/Shutterstock.com
Pitman arm Idler arm
Outer tie rod Outer tie rod
Tie rod sleeve Tie rod sleeve
Inner tie rod Inner tie rod
Center link
Figure 25-11.
Tie rods connecting steering arms (knuckles) to the center link (relay rod).
Geo
Ball
socket
Clamp
Tie rod
adjusting sleeve
Threads
Figure 25-12.
Adjustable tie rod end. The ball socket can be screwed in
or out of tie rod. When proper adjustment is achieved, it is
retained by tightening the clamp on the tie rod. This will bind
the tie rod threads against those on the ball socket end.
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