Air System Preventive Maintenance
– 160 – Y53-6008
Medium Duty (R10/06)
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 con-
taining 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 recom-
mended procedures. Some components contain
powerful springs and injury or death can result if
not properly disassembled. Use only proper
tools and observe all precautions pertaining to
the use of those tools.
• Completely bypassing a Bendix AD-IS air dryer will
bypass the system’s pressure protection valves.
This could lead to loss of air pressure or damage to
the vehicle’s air system, which could cause an acci-
dent or personal injury. Always adhere to the manu-
facturer’s procedure if it is necessary in an
emergency to temporarily bypass an AD-IS-series air
dryer.
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
pressure for brake application. Because accept-
able air leakage levels cause all truck air sys-
tems to gradually 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.
