Inspection; Removal - PREVOST H3-41 Maintenance Manual

SECTION 16 : SUSPENSION
stability on the road. All shock absorbers are
eye-type mountings. The front and tag axles are
each provided with two shock absorbers while
the drive axle is provided with four of them.
Shock absorbers are non-adjustable and non-
repairable. Maintenance requirements involve
replacement of the rubber mounting bushings,
and tightening of all shock absorber pins
according to Torque Table under heading
Torque Specifications when shock absorber
replacement occurs. If
becomes inoperative, complete unit must be
replaced.
CAUTION
When a shock absorber is found defective,
always replace with a new set on affected
axle, except if there has been a recent
replacement of one unit. The following method
will help in determining if both shock absorbers
on the same axle have to be replaced.
3.2.1

Inspection

Loosen lower mounting of both shocks, and then
carefully attempt to raise and lower the bottom
portion of each shock. Note the rate of effort for
distance of travel. Replace both shocks if a
definite differential rate is found.
The shock must be bench checked in an upright,
vertical position. If checked in any other position,
air will enter the cylinder tube and make the
shock absorber appear defective.
Proceed as follows to check shock absorbers:
1. With the shock absorber in a vertical position
(top end up), clamp the bottom mount in a
vise.
CAUTION
Do not clamp the reservoir tube or the dust
tube.
2. Rotate the dust tube. Notice any binding
condition (may be compared with new unit).
Binding condition indicates a scored rod.
Units with scored rods should be replaced.
3. Fully extend shocks and check for leaks in
the seal cover area. Shock fluid is a very thin
hydraulic fluid that has a characteristic odor
and dark brown tint. A slight trace of shock
fluid around the seal cover area is not a
16 PA1621 Maintenance Manual All Series | Section revised October 2018
a shock absorber
cause for replacement (Refer to the SACHS
document "Guideline to Evaluate Warranty
Claims" annexed at the end of this section
before replacing a shock). The shock seal is
designed to permit a very slight seepage to
lubricate the rod. Units that leak should be
replaced.
4. Visually check shock for dents that could
cause the shock to bind. Also, check for a
bent rod.
5. Extend and collapse shock several times to
determine that it has control (resistance) in
both rebound and compression.
6. Visually inspect the shock mountings and
vehicle mounting for:
a. Broken mounts;
b. Extreme bushing wear;
c. Shifted bushing or sleeve;
d. Deep cracks
(shallow surface cracks are normal);
e. Loose shock absorber pins;
f. Presence of convex washers, and their
position relative to the rubber bushing.
3.2.2

Removal

1. Remove nuts and washers from shock
absorbers on upper and lower mounting
pins, taking care to identify the inner and
outer washers to ease reinstallation. Refer to
Figure 4 for details.
2. Remove the shock absorber assembly from
pins.
3. Remove the two inner bushings from the
shock absorber and discard them.
in bushing material