SECTION 16: SUSPENSION
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Section 16 revised April 2019)
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1. DESCRIPTION
The vehicle is provided with an air suspension
system. The system consists of air springs,
height control valves, radius rods, sway bars,
tripod and shock absorbers (Figure 1 to Figure
6). The system operation is fully automatic and
maintains a constant vehicle height regardless
of load, or load distribution.
The vehicle is also equipped with a front
kneeling system.
2. FRONT I-BEAM AXLE SUSPENSION
FIGURE 1: FRONT I-BEAM AXLE SUSPENSION
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2.1 AIR
SPRINGS
The air springs are made from a special
compound rubber molded to the proper contour
and dimensions. The entire vertical load of the
vehicle is supported by these springs. Each of
the three axles is provided with air springs that
are attached to the subframe and to the axles.
2.1.1
Inspection
1. Check operation of bellows.
2. Visually inspect bellows for evidence of
cracks, punctures, deterioration, or chafing.
Replace the bellows if any damage is
evident.
3. With the primary air system at normal
operating pressure (95 - 125 psi (655 - 860
kPa)), coat all suspension air line
connections and bellows mounting areas
with a water and soap solution. Bubbles will
indicate an air leak, and none is
permissible. Repair or replace defective
parts.
FIGURE 2: AIR SPRING
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NOTE
If air spring is removed from vehicle, bellows
can be lightly inflated and submerged in water
to detect any leakage. If any leakage is
detected, replace bellows.
WARNING
To prevent personal injury, do not apply more
than 10 psi (69 kPa) of air pressure to the
uninstalled air spring.
2.1.2
Removal
NOTE
Front suspension air springs can be removed
without removing the entire axle assembly.
1. Safely support vehicle at the recommended
body jacking points. To gain access to a
given air spring, the corresponding wheel
can be removed as follows:
a) Jack vehicle until the tire clears the
ground, and place safety supports
underneath body.
CAUTION
Only the recommended jacking points must be
used as outlined in Section 18, “Body”.
b) Support the axle with a suitable
hydraulic floor jack at the
recommended jacking points. Make
sure that the measurement between
the air spring mounting plates is
greater than the normal clearance
(normal ride height).
c) Remove
wheel.
