Steering System
General Information
When there is no load on the vehicle, and the front
tires are pointed straight ahead, the steering wheel
spokes should be centered, ±10 degrees, as shown
in
Fig. 6.1
. See Group 46 of the
Century Class
Trucks Workshop Manual
for steering adjustment
procedures.
CAUTION
Never steam clean or high-pressure wash the
steering gear. Internal damage to gear seals, and
ultimately the steering gear, can result.
Power Steering System
The power steering system consists of an integral
steering gear (which includes a manual steering
mechanism, a hydraulic control valve, and a hydrau-
lic power cylinder), hydraulic hoses, power steering
pump, reservoir, and other components. Some
models are also equipped with a separate hydraulic
power cylinder on the right side of the front axle. The
power steering pump, driven by the engine, provides
the power assist for the steering system. If the en-
gine is not running, there is no power assist. If the
power-assist feature does not work due to hydraulic
fluid loss, steering pump damage, or some other
cause, bring the vehicle to a safe stop. Do not drive
the vehicle until the cause of the problem has been
corrected.
WARNING
Driving the vehicle without the power-assist fea-
ture of the steering system requires much greater
effort, especially in sharp turns or at low speeds,
which could result in an accident and possible
injury.
Drivers should carefully use the power available with
a power steering system. If the front tires become
lodged in a deep chuckhole or rut, drive the vehicle
out, instead of using the steering system to lift the
tires from the hole. Also, avoid turning the tires when
they are against a curb, as this places a heavy load
on steering components and could damage them.
Brake System
General Information
A dual air brake system consists of two independent
air brake systems which use a single set of brake
controls. Each system has its own reservoirs, plumb-
ing, and brake chambers. The primary system oper-
ates the service brakes on the rear axle; the second-
ary system operates the service brakes on the front
axle. Service brake signals from both systems are
sent to the trailer.
WARNING
Do not operate the vehicle with the front brakes
backed off or disconnected. Backing off or dis-
connecting the front brakes will not improve ve-
hicle handling and may lead to loss of vehicle
control, resulting in property damage or personal
injury.
Loss of air pressure in the primary system causes
the rear service brakes to become inoperative; front
brakes will continue to be operated by secondary
system air pressure. In addition, trailer brakes will be
operated by the secondary system. Loss of second-
ary system air pressure causes the front axle brakes
to become inoperative; rear service brakes and trailer
brakes will be operated by the primary system.
Before driving your vehicle, allow time for the air
compressor to build up a minimum of 100 psi (689
10/15/98
f461694
10°
10°
1
2
10°
10°
1.
9 o’Clock
2.
3 o’Clock
Fig. 6.1, Proper Steering Wheel Position (with tires
pointed straight ahead)
Steering and Brake Systems
6.1
