SECTION 16: SUSPENSION
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Section 16 revised April 2019)
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Reverse removal procedure to replace height
control valve. After installation, check for
leakage using a soap and water solution.
8. AIR
SYSTEM
The basic air system consists of an air
compressor, tanks, valves, filters and
interconnecting lines and hoses (refer to
Maintenance Manual, Section 12, "Brake and Air
System" for complete information). It provides a
means for braking, operating controls and
accessories, and suspension. An air system
schematic diagram is provided for a better
understanding of the system.
The air coming from the air dryer is first directed
to the wet air tank, then to the primary (for the
primary brake system), secondary (for the
secondary brake system), and accessory (for the
pneumatic accessories) air tanks (Figure 22).
8.1 AIR TANK MAINTENANCE
Ensure that the accessories air tank is purged
during pre-starting inspection. A good practice is
to purge this tank at the end of every driving day
by the remote air tank drain valve located in the
front service compartment (Figure 24).
Moreover, purge all tanks by their bottom drain
valves at specified intervals.
8.1.1
Wet Air Tank
This tank is installed above the drive axle on the
L.H. side, and is provided with a bottom drain
valve. It is recommended to
purge
the wet air
tank by its bottom drain valve every 12,000
miles.
A remote valve located in engine compartment
and accessible through engine R.H. side door is
used to
drain
the air dryer (Figure 23).
8.1.2
Primary Air Tank
The primary air tank is located above the drive
axle on the R.H. side (Figure 22).
This tank is provided with a bottom drain valve. It
is recommended to purge the primary air tank by
its bottom drain valve every 12,000 mile.
8.1.3
Secondary Air Tank
This tank is located in front wheelhousing,
between air springs. The tank is provided with a
bottom drain valve (Figure 22).
It is recommended to purge the tank by its
bottom drain valve, every 12,000 miles.
8.1.4
Accessory Air Tank
The accessory air tank is installed next to the
secondary air tank. The tank is provided with a
bottom drain valve (Figure 22).
It is recommended to purge the tank by its
bottom drain valve, every 12,000 miles.
A remote drain valve is located in front service
compartment (Figure 23) underneath the
accessory air filter. Refer to Section 12,
paragraph "4. Accessory Air Filter" of the
maintenance manual for daily purge procedure.
8.1.5
Kneeling Air Tank
The kneeling air tank is located in the front
wheelhousing (Figure 22), and is provided with a
bottom drain valve.
8.1.6
Parking Brakes Overrule Air Tank
The parking brakes overrule air tank is installed
at the ceiling of the rear baggage compartment,
on the L.H. side and is provided with a bottom
drain valve.
FIGURE 22: I-BEAM FRONT SUSPENSION AIR TANKS LOCATION
