PREVOST H3-41 Maintenance Manual page 716

SECTION 18b: X3 SERIES BODY
9.1.7 Regular Entrance Door (Coaches)
An air operated "sedan type" entrance door, with
an air door cylinder and damper assembly are
installed under the right hand dash. The opening
and closing door speed cycle is adjustable by a
damper mounted in parallel with the door
cylinder on the door hinge. Door activation is
controlled by a panel (Figure 21), located near
the defroster and wiper motors. The accessory
air reservoir supplies air to this system.
FIGURE 21: ENTRANCE DOOR & WIPER CONTROL
PANEL
The door is held in the closed position during
coach operation by a two air cylinder locking
mechanisms (Figure 23). Air cylinders with
return spring in the cylinder body are used. Air
cylinders are controlled by an electrically
operated solenoid valve energized by a rocker
switch located under the right hand dashboard.
To open the door, initial movement of the rocker
switch energizes the air lock solenoid valve,
venting the door locking cylinders. The return
locking spring pulls the door lock away from the
latch, unlocking the door. Door movement starts
only when pressure in the central air door lock is
below 10 psi. The "air cylinder open solenoid
valve" opens and allows air to flow to the door
cylinder, "the air cylinder close solenoid valve"
exhausts air from the rod side of the cylinder.
To close the door, initial movement of the switch
energizes the "air cylinder close solenoid valve"
and air flows to the cylinder by its rod side port.
The "air cylinder open solenoid valve" exhausts
air from cylinder. When the reed switch signals
the door as closed, the air lock solenoid valve is
de-energized and loads the door lock cylinders.
The cylinder moves the door lock in a position
which engages a latch on the entrance door,
holding the door positively closed.
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PA1621 Maintenance Manual All Series | Revised Sept 2019
Emergency exit valve, which opens the air valve
circuit should be used only in emergencies, or
when the door control system does not function
properly.
Refer to the air system schematic diagram
annexed at the end of section 12, "Brakes" and
to page 22 of the wiring diagram.
Operation
•
The air-operated door is controlled from inside
the coach by two push-button switches located
on the R.H. dashboard.
FIGURE 22: ENTRANCE DOOR OPERATING BUTTONS
06464
Opening and closing of the door from outside the
coach is accomplished by a momentary toggle
06619
switch located under the front R.H. side marker
light (Figure 24).
To close the door, the switch must be pushed
towards the rear of the coach and held in
position until the door has completed its
movement.
FIGURE 23: COACH ENTRANCE DOOR
18642