Holiday Trip 2012, Owner'S Manual

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2012 Trip
Shut engine off then turn key to
ignition on.
Fan (apply/release in quick succession)
service brake pedal.
Low air warning indicator will sound no
lower than 60 psi.
Park Brake Apply Test:
The park brake will automatically apply if
low air warning indicator(s) are ignored and
system pressure falls well below safe operating
levels. A flat, level surface is required as the
park brake will be released with the engine off.
Chock wheels to prevent vehicle movement.
Start engine.
Run engine until low air warning
indicators are inactive.
Shut engine off.
Release park brake.
Fan (apply/release in quick succession)
service brake pedal.
The park brake will automatically apply
between 20 to 40 psi.
Park Brake Hold Test:
This test will verify engagement of the park
brake. A flat, level surface is required. While
the test is performed with the park brake
applied, use precautions in case of vehicle
movement. This test only verifies the park
brake is engaged. It is not intended to verify
the maximum amount of braking force created
by the park brake.
Start engine.
Place transmission into gear. Do not
release park brake.
Apply light throttle, not to exceed
1,000 RPM.
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Test confirms that the park brake is engaged
and holding.
Air Governor Cut-In Test:
The air governor controls action of the
air system pump. This will confirm the air
governor cut-in pressure setting.
Start engine.
Run engine until a chuff (air release) is
heard from the air dryer.
Fan (apply/release in quick succession)
service brake pedal until system
pressure is between 100 and 110 psi.
Air governor cut-in pressure is
approximately 110 psi.
Brake Grab Test:
This test will verify brake friction torque
between the front wheels. This test requires a
rapid and full pressure application of service
brake pedal. Use proper precautions to prevent
movement of cargo or other items that are not
secured. This is a single vehicle test. Select
deserted and level road surface (preferably
a large and empty parking lot). Road crown,
depending on severity, may affect test results.
Start engine.
Run engine until a chuff (air release) is
heard from the air dryer.
Release park brake.
Accelerate to approximately 5 mph.
Rapidly and firmly apply service
brake pedal to bring vehicle to an
abrupt stop.
The steering wheel will not pull to the
left or right if front wheel braking torque is
symmetrical.
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aIr Dryer
The air dryer, located between the frame rails
next to the transmission, removes moisture
from the compressed air system to prevent
freezing of brakes or other pneumatically
operated items. The three functions of the
air dryer are cooling, filtering and drying
the system air. This prevents valve and seal
damage or wash away of lubricants as well as
freeze damage to the system components.
Air Dryer Cycle:
The governor turns the compressor on when
the supply tank pressure drops below cut-in
pressure. Compressed air then passes into the
air dryer at the inlet port. Moisture-laden air
and contaminants pass through the desiccant.
Moisture is retained by the desiccant and
collects in the base of the dryer. When the
compressor reaches cut-out pressure the
purge valve opens and the dryer purges and
expels water collected in the dryer base. The
regeneration valve opens sending a small
charge of dry system air from the front air tank
back through the dryer. The backflow dries the
desiccant, preparing it for the next cycle.
Air Dryer Components:
1. Purge Valve: A valve located on
the bottom of the air dryer base that
remains open during a compressor
unload cycle to allow collected
moisture, condensation and
contamination to expel from the air
dryer during the purge cycle.
2. Pressure Relief Valve: Protects the
air dryer from over-pressurization.