operators_manual

Periodically
Clean filter screens ahead of the valves by
removing the screens and soaking them in
solvent. Blow them dry with pressurized air
before reinstalling them.
• Maintain the air compressor to
prevent excessive oil bypass.
• Replace worn seals in valves and
air motors as they are needed. Your
authorized dealer carries rebuild kits
for most units.
How to Check for Air
System Leaks
Use these steps if the air gauges in the
dash or any warning lights turn on that
indicate that a air leak exists in the system.
Checking for air leaks should also be done
after any service or repair has been done
to the air system.
WARNING!
Do not operate the vehicle if leakage in the
air system is detected. Conduct the follow-
ing procedure and contact an authorized
dealer (or any other properly equipped serv-
ice 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 accident and may result in death,
personal injury,equipment or property dam-
age.
1. Build up air pressure in the system
to the governor cutout point or until
120 psi (827 kPa) is reached.
2. Stop the engine and release the
service brakes.
3. Without applying the brake pedal,
observe the rate of air pressure
drop. This rate should not exceed
2.0 psi (14 kPa) per minute.
4. Start the engine and build up the air
pressure again.
5. Stop the engine, and apply the
brakes fully. Apply the brake pedal
and hold it down for five minutes.
The pressure drop should not
exceed 3.0 psi (21 kPa) per minute.
6. If you detect excessive leakage (air
pressure loss greater than 3.0 psi
(21 kPa) after five minutes of brake
application), a leakage test should
be made at the air line connections
and at all air brake control units.
These tests should determine where air is
escaping.
What is an Air
Compressor?
Air systems have an air compressor that
provides compressed air to the system.
All compressors, regardless of make or
model, run continuously while the engine is
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,
MAINTENANCE - How to Check for Air System Leaks
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