Operation - PREVOST H3-41 Maintenance Manual

SECTION 18a: H3 SERIES BODY
FIGURE 12: REAR BUMPER ASSEMBLY
10. COACH ENTRANCE DOOR
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 (Figure 15). Door
activation is controlled by a relay panel, located
near the defroster and wiper motors.
accessory air reservoir supplies air to this
system.
The door is held in the closed position during
coach operation by two air cylinder locking
mechanisms (Figure 16). 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 de-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 entrance door latch is
grounded with the door frame, 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.
Emergency exit valves, which open the air valve
circuit, should be used only in emergencies, or
24
PA1621 Maintenance Manual All Series
when the door control system does not function
properly.
Refer to the air system schematic and page 22
of the wiring diagram available on the technical
publications web site.

10.1 OPERATION

The air-operated door is controlled from inside
the coach by two push-button switches located
on the R.H. dashboard.
Opening and closing of the door from outside the
18501
coach is accomplished by a momentary toggle
switch located
nameplate (Figure 13).
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.
To open the door, the switch must be pushed
towards the front of the coach and held in
position. When the door reaches the fully
The
opened position, the system will keep pressure
in the cylinder locking the door in that position.
The door can be stopped in any position by
releasing the switch. The door is not locked in
position when not fully opened or closed.
If the door has been locked with the key, a lever
on the door can be moved to unlock.
FIGURE 13: DOOR OPERATING SWITCH
10.2 EMERGENCY EXIT VALVES
From inside the vehicle, an emergency exit valve
located near the door on the dash panel,
releases the pressure from the lock cylinders.
From the exterior, an emergency exit valve
located in the front service compartment, also
releases the air from the lock cylinders.
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Revised Sept 2019
behind the coach model
18316