Chapter 9 Steering Systems 183
Tie Rods
A tie rod assembly is attached to each end of the relay
rod. The tie rod assembly consists of inner and outer tie
rods that are usually connected through an adjusting
sleeve. See Figure 9-36.
Hydraulic Damper
Some vehicles have a hydraulic damper installed
between the relay rod and the frame or axle, Figure 9-37.
The hydraulic damper resembles a shock absorber. Its
function is to absorb road shocks. A hydraulic piston inside
the damper allows small amounts of hydraulic fluid to pass
through calibrated holes. This absorbs the energy from
road shocks before they reach the steering gear.
Power Steering Systems
Power steering is a steering system feature that
reduces driver effort by providing extra force to steer the
vehicle. The use of power steering has increased to the
point that all but the smallest cars are equipped with power
steering as standard equipment. Power steering systems are
used on both rack-and-pinion and conventional steering
systems. Principles of power steering are discussed in the
following sections.
Pressure Development and Control
The basic operating principle of power steering is that
liquids (in this case power steering fluid) cannot be
compressed. Therefore, liquids can be used to transmit
pressure and movement. Systems that make use of liquids
to transfer pressure are called hydraulic systems, and the
pressure exerted by the liquid is called hydraulic pressure.
Observe the closed hydraulic system in Figure 9-38.
Hydraulic pressure is transmitted through the hose to one
side of the piston. This pressure causes the piston to move.
Pitman
arm
Relay rod
Connecting rod
Figure 9-32. This connecting rod is located between the pitman
arm and the relay rod. (General Motors)
Hydraulic steering
damper
Nut
Drag link
Tie rod
Washer
Pitman arm
Figure 9-33. In some systems, two long linkage rods are used instead of a relay rod and tie rods. (Chrysler)