OPERATOR'S MANUAL

Preventive Maintenance Air System
Model 330 PB1318 3/01 – 163 –
AIR SYSTEM
Introduction
WARNING! Prior to the removal of any air system
component, always block and hold the vehicle
by a secure means other than the vehicle’s own
brakes. Depleting air system pressure may
cause the vehicle to roll unexpectedly resulting
in an accident and/or injuries. Keep hands away
from chamber push rods and slack adjusters,
they may apply as system pressure drops.
• Never connect or disconnect a hose or line contain-
ing air pressure. It may whip as air escapes. Never
remove a component or pipe plug unless you are
certain all system pressure has been depleted.
• Never exceed recommended air pressure and always
wear safety glasses when working with air pressure.
Never look into air jets or direct them at anyone.
• Never attempt to disassemble a component until you
have read and understood recommended proce-
dures. Some components contain powerful springs
and injury or death can result if not properly disas-
sembled. Use only proper tools and observe all pre-
cautions pertaining to the use of those tools.
WARNING! Do not release the parking brake or
attempt to move the vehicle until air pressure in
both circuits is at least 100 psi (690 kPa), the
level required for normal brake operation.
• Do not use the trailer hand brake control to hold
vehicle while parked. This control utilizes air pres-
sure for brake application. Because acceptable air
leakage levels cause all truck air systems to gradu-
ally lose pressure, vehicle rollaway could occur,
resulting in an accident and/or injuries.
• Always apply the tractor and trailer parking brakes
when the vehicle is unattended.
Contamination of the air supply system is the major cause of
problems in air-operated components such as brake valves,
wiper motors, and suspension height control valves. To keep
contaminants to the lowest possible level, follow these main-
tenance procedures.