PREVOST H3-41 Maintenance Manual page 724

SECTION 18b: X3 SERIES BODY
9.1.8 Commuter Type Entrance Door
An air operated entrance door, with an air door
cylinder and damper assembly installed under
the right hand dash for the R.H. door panel
opening. Another air door cylinder is installed
behind the wall to the right of the first curb-side
passengers' seat for the L.H. door panel
opening. The opening and closing door speed
cycle is adjustable by a damper mounted in
parallel with the R.H. door panel cylinder on the
door hinge. Door activation is controlled by a
panel (Figure 30), located near the defroster and
wiper motors. The accessory air reservoir
supplies air to this system.
FIGURE 30: ENTRANCE DOOR & WIPER CONTROL
PANEL
06619
The door is held in the closed position during
coach operation by a two air cylinder locking
mechanisms (Figure 31).
40
PA1621 Maintenance Manual All Series | Revised Sept 2019
FIGURE 31: ENTRANCE DOOR - VIEW FROM INSIDE
Air cylinders with return spring in the cylinder
body are used. Air cylinders are controlled by an
electrically operated solenoid valve energized by
a multiplex module located under the right hand
dashboard.
To open the door, initial action from multiplex
module output 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 cylinders, "the air cylinder
close solenoid valve" exhausts air from the rod
side of the cylinders.
To close the door, initial movement of the switch
energizes the "air cylinder close solenoid valve"
and air flows to the cylinders by their rod side
ports. The "air cylinder open solenoid valve"
exhausts air from cylinders. When the sensor
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