PREVOST H3-41 Maintenance Manual page 718

SECTION 18b: X3 SERIES BODY
It is important to make sure that damper does
not reach end of stroke when door is
completely closed or opened. The door
cylinder must stop the door on opening. Screw
or unscrew rod end to adjust if necessary.
To adjust opening and closing cycle speed on
damper (Figure 27):
1. Remove the damper from the vehicle and
hold it vertically with the lower eye or pin
attachment in a vice. Use clamp plates to
prevent damage.
2. Fully close the damper while turning the dust
cap or piston rod slowly CCW until it is felt
that the cams of the adjusting nut engage in
the recesses of the foot valve assembly
(Figure 27).
NOTE
In Figure 27, if there is an indentation (B) in
the dust cap (C) and the cover shows two
holes (A), the damper is fitted with a bump
rubber (D). If so, fully extend the damper and
insert a round bar or screwdriver through the
holes. Push the bump rubber down and
remove. Remove the split plastic collar (E) (if
fitted) from the piston rod.
3. The damper may have already been
adjusted. Therefore check whether the
damper is adjusted or not by keeping it
closed and gently turning further CCW,
counting at the same time the half-turns until
a stop is felt. Stop turning and do not force.
4. While keeping the damper closed, make two
CW half-turns. In case of prior adjustment,
add the number of half-turns previously
counted. The total range is about five half-
turns. Pull the damper out vertically without
turning for at least 3/8" (1cm) to disengage
the adjusting mechanism. The dust cap or
piston rod may now be turned freely.
5. The damper can now be refitted in the
vehicle.
34
PA1621 Maintenance Manual All Series | Revised Sept 2019
FIGURE 27: DAMPER
NOTE
Where a bump rubber was installed, refit same
inside the dust cap and by fully closing the
damper, the rubber will seat again at top of the
dust cap. Refit the split plastic collar E (Figure
27).
6. Reinstall panels and entrance door hinge
cover.
• Horizontal And Vertical Adjustment
Before attempting to correct any door operating
problem by adjusting any part of the air cylinder
assembly, first perform the following mechanical
checks and procedure.
Check around the perimeter of the door for
binding. If any binding is found, adjust as follows:
1. Remove the screws and the plastic molding
covering each of the hinges.
NOTE
Ask an assistant to help you to perform the
following adjustments.
2. Remove the Allen button head screw and
the washer retaining the rod end with
bearing to the upper hinge. See Figure 28.
3. Support the door with a wooden block and a
hydraulic jack.
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