Paccar Peterbilt 567 2021, Manual

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Dual Air System Function
Test
Conduct this test at least every 3 months
or if there is any indication of a potential
problem.
Park the vehicle on level ground and block
the wheels. Have an assistant open drain
valves and, where required, observe brake
action at the wheels. If a malfunction
occurs during this test, do not move the
vehicle until the problem has been
corrected. Engine should be Off with the
key switch to the ON or RUN position.
NOTE
Tractor air system must be connected
to trailer.
Air Dryer Maintenance
NOTE
Because no two vehicles operate un-
der identical conditions, maintenance
and maintenance intervals will vary.
Experience is a valuable guide in de-
termining the best maintenance inter-
val for any one particular operation.
NOTE
A small amount of oil in the system
may be normal and should not, in it-
self, be considered a reason to replace
the desiccant cartridge. Oil stained
desiccant can function adequately.
Every 900 operating hours or 25,000 miles
(40,000 km) or every 3 months check for
moisture in the air brake system by
opening air tanks, drain cocks, or valves
and checking for presence of water.
A tablespoon of water found in the air tank
would point to the need for a desiccant
cartridge change. However, the following
conditions can also cause water
accumulation and should be considered
before replacing the desiccant cartridge.
• Air usage is exceptionally high and
not normal for a highway vehicle.
This may be due to accessory air
demands or some unusual air
requirement that does not allow the
compressor to load and unload
(compressing and non-
compressing cycle) in a normal
fashion or it may be due to
excessive leaks in the air system.
• In areas where more than a 30°F
(17°C) range of temperature occurs
in one day, small amounts of water
can accumulate in the air brake
system due to condensation. Under
these conditions, the presence of
small amounts of moisture is
normal and should not be
considered as an indication that the
dryer is not performing properly.
• An outside air source has been
used to charge the air system. This
air did not pass through the drying
bed.
MAINTENANCE - Dual Air System Function Test
234 Y53-6126-1A1 (01/21)
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