Air Dryer; Replacing The Desiccant Cartridge - PREVOST H3-41 Maintenance Manual

SECTION 12: BRAKE AND AIR SYSTEM

8. AIR DRYER

TORQUE for connections:
3/8"-18 NPTF= 12 lb-ft (16 Nm)
1/4"-18 NPTF= 12 lb-ft (16 Nm)
1/2"-14 NPTF= 37 lb-ft (50 Nm)
Safety valve dynamic pressure: 290 psi.
FIGURE 6: AIR FILTER DRYER
The electric air dryer is controlled by the
multiplex system. If the air dryer should for some
reason become powerless, it will cease to
function and the desiccant will become wet
through, while the compressor will continue to
charge. Relief is provided via the safety valve.
By using the information from the vehicle
electronic system, the air dryer and compressor
control is optimized, so that drying of the air is
guaranteed and fuel consumption is reduced.
This will be noticed as a different compressor
start/stop pattern.
The air dryer has a built-in function to prevent
freezing or blockage. The function provides
temporary relief (air dryer blow clean) at engine
shut down. This function eliminates the problem
of freezing on a stationary vehicle.
An additional function
prevents the compressor from charging air
during engine cranking and start-up.
The air filter/dryer is located in front of rear
wheel housing above drive axle. Its purpose is to
remove moisture that could damage the air
12 PA1621 Maintenance Manual All Series | Revised June 2020
at vehicle start-up
system before the air enters the system
reservoir. The air filter/dryer also filters the air to
remove dirt, compressor
contaminants that can damage the system.
Change cartridge every 100,000 miles (160 000
km) or once every two years, whichever comes
first.
FIGURE 7: REAR VALVE LOCATION (TYPICAL)
The air dryer and wet tank may be purged
simultaneously for maintenance purposes using
the drain cock on the emergency air system fill
valve located in the engine compartment and
accessible through the engine compartment
R.H. side door (Figure 7).
For more information on Meritor Wabco Air
dryer, refer to the following manuals included on
your Technical Publications USB flash drive:
Meritor Wabco System Saver Series
•
Single Cartridge Air Dryers Mainte-
nance Manual 34
8.1 REPLACING THE DESICCANT
CARTRIDGE
To replace the desiccant cartridge:
5. Release air dryer pressure by opening the
air dryer drain valve (Figure 7).
6. Loosen and remove the old cartridge. Use
strap wrench if necessary.
7. Remove and discard O-ring from dryer base.
8. Inspect and clean seal seat. Repair any
minor damage.
9. Lubricate and install new O-ring on stem.
10. Lubricate cartridge seal.
oil, and other