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
Columbia
®
Work-
shop 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 that use a single set of brake con-
trols. Each system has its own reservoirs, plumbing,
and brake chambers. The primary system operates
the service brakes on the rear axle; the secondary
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.
IMPORTANT: On TRACTORS, loss of air pres-
sure in the primary system causes the rear ser-
vice brakes to become inoperative; front brakes
will continue to be operated by secondary sys-
tem air pressure. On TRUCKS, loss of air pres-
sure in the primary system causes the rear
spring brakes to get modulated, controlled by a
secondary air signal. In addition, on TRACTORS
and TRUCKS, trailer brakes will be operated by
the secondary system.
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
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