Owner`s manual

CHASSIS INFORMATION — 10
194
2008 KNIGHT
Desiccant-Type Air Dryer
1. Warm, humid air from the compressor
condenses into either water or water
vapor before entering the air dryer.
2. A desiccant-type air dryer protects the
motorhome air brake system by drying
moisture-laden air before it passes
through the air reservoirs and into the
brake system.
3. Water collects in the base of the dryer
when warm air condenses the water
before it enters the dryer, or inside of
the dryer before the water reaches the
desiccant.
4. The desiccant material then removes
additional water vapor, further drying
the air.
5. During regeneration phase, the
regeneration valve and pressure-
controlled check valve remove water
from the desiccant bed with a backow
of dried, expanded system air.
Air Dryer Cycle
The governor turns the compressor on when
the supply tank pressure drops below cut-in
pressure. Compressed air passes into the air
dryer at the inlet port:
1. Moisture-laden air and contaminants
pass through the desiccant.
2. Moisture is retained by the desiccant.
Moisture also collects in the base of the
dryer.
3. The governor turns the compressor
off when the system reaches cutout
pressure (approximately 135 psi).
4. The dryer purges and expels water
collected in the dryer base.
5. When the regeneration valve opens, the
dry system air ows back through the
dryer. A small charge of air from the
front air tank backows through the
lter. The backow dries the desiccant,
preparing it for the next cycle.
AIR SPRING INSPECTIONS
Items listed below should be checked when the
motorhome is in for periodic maintenance.
NOTE
Never attempt to service the air
suspension on a motorhome with the air
spring inflated.
Inspect the Outer Diameter (OD) of the
air springs. Check for irregular wear or
heat cracking.
Inspect air lines to ensure contact does
not exist between air line and OD of the
air springs. Air lines can rub a hole in an
air spring very quickly.
Ensure there is sufcient clearance
around the complete circumference
of the air spring while at maximum
diameter.
Inspect the OD of piston for buildup of
foreign materials. On a reversible sleeve
style air spring, the piston is the bottom
component of the air spring.
The correct ride height should be
maintained. All motorhomes with air
springs have a specied ride height
established by the manufacturer. This
height should be maintained within ¼
inch. This dimension can be checked
with the motorhome loaded or empty.
The leveling valves (or height control
valves) assist in ensuring the total air
spring system works as required. Clean,
inspect and replace if necessary.
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REPLACEMENT REQUIREMENTS
Components When to replace? Why?
Desiccant Cartridge
• Every two to three years.
• When compressor is
replaced.
• Water in supply tank.
• Preventive maintenance.
• Contaminated cartridge.
• Saturated or contaminated
cartridge, high duty cycle
(wrong application of air dryer).