PREVOST X3-45 Multiplex, Maintenance Manual

Page: 993 / 1422

Section 16: SUSPENSION
PA1562
25
3.16.6 Major Damage
If the suspension has sustained major damage,
it may be necessary to shim the bell crank and
the idler arm to avoid the bump steer or roll
steer. Moreover refer to paragraph "3.16: Front
End Alignment".
3.17 FRONT AIR SPRINGS
Two "rolling lobe" type air springs are used with
the independent front suspension, one at each
wheel. These air springs are special and use the
complete piston as an extra reservoir to lower
the spring stiffness. Front air springs are
attached to the subframe and to uprights.
FIGURE 31: AIR SPRINGS
16052
3.17.1 Inspection
1. Check operation of bellows.
2. Visually inspect bellows for evidence of
cracks, punctures, deterioration, or chafing.
Replace the bellows if 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 bellow mounting areas with
a water and soap solution. Bubbles will
indicate an air leak, and none is permissible.
Repair or replace defective parts.
NOTE
If air spring is removed from vehicle, bellows
can be lightly inflated and submerged in water
to detect any leakage. If leakage is detected,
replace bellows.
WARNING
To prevent personal injury, do not apply more
than 10 psi (69 kPa) air pressure to the
unmounted air spring.
3.17.2 Removal
NOTE
Front air springs can be removed without
removing the entire suspension assembly.
1. Safely support vehicle at the recommended
body jacking points and jack up body
understructure.
2. To gain access to a given air spring, the
corresponding wheel can be removed.
CAUTION
Only the recommended jacking points must be
used as outlined in Section 18, "Body" in the
maintenance manual.
3. Support the assembly with a suitable jack.
4. Exhaust compressed air from accessory air
tank by opening drain cock under reservoir.
5. Disconnect the height control valve link and
pull down the overtravel lever to ensure all
air is exhausted from air springs.
NOTE
While performing this step, do not change the
height control valve overtravel lever
adjustment.
6. Disconnect air line from air spring, remove
elbow (if applicable), and cover both the line
end and fitting to prevent the entry of foreign
matter.
7. Remove the air spring upper nut, and then
the two lower nuts. Remove air spring and
remove the back up plate from the top of the
air spring.
3.17.3 Installation
NOTE
To facilitate air spring installation, compress it
manually then put a piece of tape over the air
line threaded fitting. This prevents air from
getting back into the bag and keeps it
compressed, thus enabling to place the bag in
between the mounting plates and greatly
easing installation.