User Manual

running. System pressure is controlled by
the governor
. The governor acts in
conjunction with the unloading mechanism
in the compressor cylinder block to start
and stop compression of air. The
compressor is unloaded when the system
pressure reaches 120 psi (827 kPa) and
compression is reestablished when system
pressure falls to 100 psi (690 kPa).
Preventive Maintenance
The following service checks are provided
for your information only and should be
performed by a certified mechanic. Contact
your dealer or the engine manufacturer's
Maintenance Manual for further information
on servicing air compressors. After
completing any repairs to the air system,
always test for air leaks, and check the
brakes for safe operation before putting the
vehicle in service. Below is a list of areas
to maintain for the air compressor:
• Inspect compressor air filter
element, if so equipped, and
replace element if clogged. Check
compressor mounting and drive for
alignment and belt tension. Adjust
if necessary.
• Remove compressor discharge
valve cap nuts and check for
presence of excessive carbon. If
excessive carbon is found, clean or
replace the compressor cylinder
head. Also, check compressor
discharge line for carbon, and
clean or replace the discharge line
if necessary.
• Disassemble compressor and
thoroughly clean and inspect all
parts. Repair or replace all worn or
damaged parts, or replace
compressor with a factory
exchange unit.
Brake System
To learn more about brakes, see the Index,
under Brakes.
WARNING
DO NOT work on the brake system
without the parking brake set and
wheels chocked securely. If the vehicle
is not secured to prevent uncontrolled
vehicle movement, it could roll and
cause damage to the vehicle, serious
personal injury, or death.
CAUTION
The air brake system of this vehicle
was
configured for ONE of the follow-
ing operations: tractor or truck, and
complies with the respective portions
of FMVSS 121. A tractor shall not be
operated or configured as a truck, nor
shall a truck be operated or configured
as a tractor, without significant modifi-
cations to the air brake system in order
to retain compliance with FMVSS 121.
Contact your dealer for instructions.
WARNING
DO NOT use brake linings with a thick-
ness
below the specified minimum.
Such linings will have lining rivets ex-
posed that can damage the brake
drum and reduce brake efficiency,
which could cause death, personal in-
jury or system failure.
MAINTENANCE - Brake System
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