MCi Crusader II 1989 Maintenance Manual page 103

Date
1-1-89
Page ___
3_-2_s _ _
MC-9 MAINTENANCE MANUAL
MCI Bl-PARTING ENTRANCE DOOR (OPTION)
AND CONTROL MECHANISM
DESCRIPTION
The Bi-Parting Entrance door is an air power operated,
two-piece, outward opening type door. Clear opening of the
entrance door is 24 inches by 83 inches (609.6 by 2108 mm).
Meeting edges of the door panels are provided with flexible
rubber cushions, 2 inches (51 mm) wide for passenger pro-
tection. Door panels are double glazed at the top with single-
density tempered safety glass. Lower windows are single
glazed with Lucite panels. The front panel has an exhaust outlet
near the bottom on the interior side.
The door panels and operating shafts are mechanically
linked to a master air-operated cylinder. The master air-
operating cylinder is a geared-differential. air-operated device
consisting of ·two horizontally opposed cylinders of different
diameters. A rack gear connects the pistons which operate
within the cylinders. The rack meshes with a gear which con-
verts the straight line motion of the pistons into rotary motion
necessary for operation of the linkage and door shafts
assemblies.
The master cylinder is designed to operate at 60 to 120 PSI
(414-828 kPa) air pressure. During normal operation. air pres-
sure is continually applied to both cylinders - djrectly to the
smaller "opening" cylinder from the reservoir, and from the
,ormally open solenoid valve to the larger or "closing" cylinder.
Joor operating pictorial and air system schematic diagrams are
found at the end of this writeup.
In the door-opening process. air pressure to the large
cylinder is shut off and permitted to bleed off at a controlled rate
through adjusting ports back through the exhaust port in the
solenoid valve. At a predetermined point in the opening cycle,
horizontal movement of the rack-and-piston assembly closes
off the primary air exhaust port by action of the seal cushion.
The greater pressure in the smaller cylinder causes the move-
ment of the piston in the large cylinder to compress the remain-
ing air which is bleeding off more slowly through the cushion-
ing speed port. This compressing action provides the means of
controlling the opening action of the doors, thus preventing the
door panels from slamming open. As the doors are fully opened.
the remaining air pressure in the large cylinder is slowly
depleted through the cushioning speed port and out through
the solenoid valve exhaust port.
In the door-closing process. air pressure is admitted through
the opening-speed port cavity which was sealed by the seal
cushion. With the aid of the compression spring, the cavity is
soon opened and the main area of the large cylinder begins to
fill with air. Due to the larger piston area in the opening cylinder,
the net force difference causes the rack to move in the closing
direction, thus closing the doors.
The rear panel and shaft is the driving medium for the front
panel and shaft. The front panel is controlled by the movement
of the rear shaft through a linkage bar below the lower step. A
oush-pull slave cylinder is connected to the front panel shaft to
,ovide the necessary force to tightly close the front panel.
Nhen the door opens the slave cylinder quickly exhausts and
the master and slave cylinders pull both panels to the open
position.
DRIVER'S SWITCH
This is a toggle switch with legend plate, located to left of
driver's position, on top forward face of switch panel. This
switch is provided for normal opening and closing of the door
by the operator while within the coach.
EXTERIOR SWITCH
The door is opened or closed from the exterior of the coach
by means of a momentary-type toggle switch. The switch must
be held in the desired position until the door has completed its
movement A legend plate is attached just under the switch.
TOGGLES
POST, REAR OF
ENTRANCE DOOR
■ I
Figure ~-24. External Entrance Door Switch Control.
The switch is located in a pocket in the exterior body panel
below the #1 RH passenger window and to the rear of the
entrance door. The pocket has a spring-loaded cover wt-lich
conceals and protects the switch (figure 3-24).
MANUAL AIR DUMP
If the electrical circuit to the solenoid valve fails while the
operator is inside the vehicle, a hand operated air valve is
provided, which allows exhausting of all air from the door
operating cylinder (figure
3-25).
With the air exhausted, the
door panels can be manually pushed to the open position. The
air dump valve is located'to the right of driver's position and
below the dash panel. This valve can be identified by a legend
plate with instructions for use, and is further identified by a
lever with a small red knob.
Figure 3-25. Air Dump Valve.