21
CLOSE
OPEN
OPEN
OPEN CUSHION
ADJUSTMENT
CLOSE CUSHION
ADJUSTMENT
CLOSE
SWITCH
CLOSE
CRANK ARM
SUPPORT TUBE
CLOSE
OPEN
OPEN SPEED
CONTROL
CLOSE
SWITCH
CLOSE SPEED
CONTROL
AIR CYLINDER
BELL CRANK
ASSEMBLY
CRANK ARM
SUPPORT TUBE
FAST
SLOW
THROTTLE
VALVE
EMERGENCY
VALVE
FIGURE 1
When the door is fully closed it is necessary for the right-hand sealing lip to close on top of the left-hand
lip to avoid catching the air flow. This is accomplished by causing the left-hand panel to close slightly ahead
of the right-hand panel. Once the left-hand panel has contacted the portal, the spring loaded tie rod collapses
and allows the right-hand panel to continue closing.
COMPONENT OPERATION
The door system operation is controlled by the following valves and safety systems:
Control Valve
A four-way solenoid activated valve that directs the air flow to either the open
(extension) or closed (retraction) side of the cylinder. This valve is activated electrically
by a signal from the driver’s control switch to open the door. The absence of an electrical
signal allows the valve to return to its normal position and the door then closes.
Emergency Valve
This is a manually operated valve that disconnects the door system from the air supply
while simultaneously venting the air from the door system. This allows the door to be
opened and closed manually.
Throttle Valve
The purpose of this valve is to limit the inrush of air into the system when the emergency
valve is turned on.
Adjustable
These are used to adjust the door opening or closing speed.
Flow Control
Valve
Close Limit
Provides a signal if the interior step lights and brake
Switch
interlock when the door is not completely closed.
