-
a decreased pressure bore
-two supply pad bores
-three hydraulic ports.
The three ports are:
-
the supply port A
-
the return port B
-
the service port C.
The selector valve bore has:
-
a ball seat, two balls and a needle
-
a piston assembly to operate the selector valve
-
an end fitting to hold the piston assembly in the bore
-
an electrical actuator to operate the piston assembly.
The decreased pressure bore has:
-
a slide valve
-
a liner
-
a spring, a cup and a retaining ring to hold the slide valve
-an end fitting to hold this assembly in the bore
-
a spring with an end cup.
Each supply pad bore has:
-
a supply pad
-
a spring
-
a liner.
The electrical actuator has:
-
two motors which control the retraction or extension of the actuator rod
-
two limit switches that cut off the power supply to the motors
-
two electrical plug-in type connectors.
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Park Brake Control Valve (102GG)
Figure 005
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INTENTIONALLY BLANK
1 1
32-45-00Page 11
1 1 Config-2 Aug 01/05 1 1 1CES 1
Park Brake Selector Valve - Operation
Figure 006 (SHEET 1)
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Park Brake Selector Valve - Operation
Figure 006 (SHEET 2)
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Park Brake Selector Valve - Operation
Figure 006 (SHEET 3)
1EFF : 401-499, 1 32-45-00Page 14 1 1 Config-2 Aug 01/05 1 1 1CES 1 When the valve is in the OFF position, the actuator rod is retracted. Hydraulic pressure at supply port A holds the lower ball against the ball seat. Port A is isolated from chamber X. Spring pressure holds the slide valve in position to disconnect service port C from port A. Hydraulic fluid flows from port C to return port B.
When the valve is in operation, the actuator rod is extended. The piston assembly holds the upper ball against the ball seat. Port B is isolated from chamber X. The needle moves the lower ball away from the seat to connect port A with chamber X. Increased hydraulic pressure in chamber X makes the slide valve move against spring pressure to connect ports A and C. Hydraulic fluid then flows from port A to port C.
In the decreased pressure position, the actuator rod stays extended. Hydraulic pressure in chamber Y together with spring pressure make a higher force than the pressure in chamber X. The slide valve moves until ports A and C are disconnected. Pressure at port C is then at 'decreased pressure' (service pressure).
When the valve is returned to its OFF position, the actuator rod and piston assembly retract. This causes the upper ball to move away from the seat. The chamber X and port B are connected. Hydraulic pressure holds the lower ball against the seat. Decrease of pressure in chamber X and spring pressure moves the slide valve to connect the ports B and
C. Hydraulic fluid then flows from port C to port B.
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B. PARK BRK Control Switch (73GG) (Ref. Fig. 007) A two position control switch identified PARK BRK installed on the center
pedestal controls the parking/ultimate emergency braking system.
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PARK BRK Control Switch (73GG)
Figure 007
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7. Operation/Control and Indicating________________________________
A. Parking Brake set to ON
When the park brake selector-switch 73GG is set to ON, the motors in the park brake control valve 102GG are energized to open the valve. When the valve is open, an electrical contact in the valve sends a signal to the BSCU and the ABCU. This causes the BSCU and the ABCU to isolate the other braking systems (Ref. 32-42-00), (Ref. 32-43-00) and (Ref. 32-44-00). Another electrical contact in the valve completes a circuit to the NWS electrical de-activation box 5GC (this sets the NLG PARKING BRAKE indicator light to ON).
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