Preventive Maintenance Air System
Medium Duty
(R10/06) Y53-6008 – 163 –
CAUTION: Do not use penetrating oil, brake
fluid, or wax-based oils in the air system. These
fluids may cause severe damage to air system
components.
• Maintain the air compressor to prevent excessive oil by-
pass. See the Medium Duty Maintenance Manual for
maintenance details.
• Replace worn seals in valves and air motors as they are
needed. Your Peterbilt Dealer carries rebuild kits for most
units.
Dual Air Gauge and Air Leaks
Your Medium Duty comes with a dual-circuit air pressure
gauge for two separate systems, Primary and Secondary:
the WHITE pointer indicates pressure in the front (Second-
ary) braking circuit; the ORANGE pointer indicates pressure
in the rear (Primary) braking circuit. The gauge indicates the
amount of air pressure in pounds per square inch (psi).
WARNING! Do not operate the vehicle if leakage
in the air system is detected. Conduct the follow-
ing procedure and contact an Authorized Ser-
vice Center (or any other properly equipped
service center) if a leak is detected. Failure to check the
brakes or follow these procedures could cause a system
failure, increasing the risk of an injury accident.
If the pressure in either or both systems is too low for normal
brake operation, i.e., either pointer falls below 60 psi (414
kPa), a warning light on the gauge will glow and the audible
alarm will sound. If the light and alarm do not turn off at start-
up, do not try to drive the vehicle until the problem is found
and fixed.
Dual Air Pressure Gauge (Air Reservoir)
02581
REAR
PRIMARY
SERVICE
CIRCUIT
(ORANGE)
FRONT
SECONDARY
SERVICE
CIRCUIT
(WHITE)
