Air Compressor; Overview Of Daily Checks - Peterbilt 220 Operator's Manual

in either or both systems is too low for
normal brake operation, i.e., one gauge
falls below 65 psi (448 kPa), a 'BRAKE
AIR' warning on the main display will be
shown and the audible alarm will sound.
NOTE
Park brakes lock up at 60 psi (414
kPa), the audible alarm will sound at
65 psi (448 kPa).
Follow the procedure below to check the
compressed air system for leaks:
1. Periodically, or after maintenance or
replacement of air system
components:
2. Build up air pressure in the system to
the governor cutout point or until 120
psi (827 kPa) is reached.
Y53-6078-1B1 (12/18/18)
3. Stop the engine and release the
service brakes.
4. Without applying the brake pedal,
observe the rate of air pressure drop.
This rate should not exceed 2.0 psi
(14 kPa) per minute.
5. Start the engine and build up the air
pressure again.
6. 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.
7. If you detect excessive leakage (air
pressure loss greater than 3.0 psi (21
kPa) after two 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

Operation
All compressors, regardless of make or
model, run continuously while the engine is
running. System pressure is controlled by
MAINTENANCE - Air Compressor
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).

Overview of Daily Checks

Overview of the driver's daily checks:
• engine oil level
• coolant level, fill cap secure
• fluid level in windshield washer
reservoir
• air filter indicator
• tires and rims
• lighting and instruments
• driver's seat and mirrors
Visual check before starting the trip:
• check that no situation can occur
(such as loose objects, improperly
attached load etc.) that may put
other road users at risk.
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