operators_manual

How to Check the Compressed Air
System for Leaks
WARNING
DO NOT operate the vehicle if leakage
in
the air system is detected. Conduct
the following procedure and contact an
authorized dealer (or any other proper-
ly 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 accident and may result in
personal injury, property damage, or
death.
Use this procedure to check the
compressed air system due to the
following:
•
After maintenance
• When an air system component is
replaced
• When a leak is suspected
• Periodically, to ensure system
integrity
To check for Air System leaks
1. Start the engine if not already
running.
2. Scroll to the Primary Gauges V
iew
to monitor Primary and Secondary
Air Pressures.
3. Build up air pressure in the system
until the system cutout setpoint or
until 120 psi (827 kPa) is reached.
4.
Turn the Ignition Switch to OFF
(stopping the engine) and then
back to the ON position, but don't
start the engine.
The Primary Gauges View will
appear.
5. Release the service brakes, and
observe the rate of air pressure
drop. This rate should not exceed
2.0 psi (14 kPa) per minute.
6. Start the engine and build up air
pressure again.
7. Turn the Ignition Switch to OFF
(stopping the engine) and then
back to the ON position, but don't
start the engine.
8.
Apply the brakes fully, holding the
pedal down for five minutes. The
pressure drop should not exceed
3.0 psi (21 kPa) per minute.
9. 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.
Air Compressor
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
MAINTENANCE - Air Compressor
Y53-6096-1C1 (09/20) 189
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