I.
Indicators
__________
(1)
A brake accumulator pressure gage is provided on both the pilots P3 panel and adjacent to the charging valve in the aft body fairing hydraulic equipment compartment. The gages measure accumulator precharge pressure.
(2)
A PARK BRAKE indicator is provided on the P10 panel on the control stand, and on the P2 EICAS panel when the parking brake is engaged.
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757 MAINTENANCE MANUAL
(3)
AIRPLANES WITH PARKING BRAKE LIGHT ON NOSE LANDING GEAR; A parking brake ON light is installed on the nose gear P62 panel. The light has a push-to-test feature.
(4)
The ANTISKID indicator light on panel P5 will illuminate and EICAS (AMM 31-41-00/001) message ANTISKID will appear in the event that the parking brake valve is not fully open when the parking brake is released (AMM 32-42-00/001).
3. Operation (Fig. 2, 3)_________
A. Functional Description
(1)
The parking brake is mechanically actuated from the flight compartment by depressing both left and right captain's or first officer's brake pedals and pulling up on the PARK BRAKE handle on the P10 panel of the control stand.
(2)
The parking brake handle is connected by cable to a mechanism which holds the brake pedals depressed. The mechanism has two shaft mounted pawls which rotate into position to hold the brake pedals in the engaged position.
(3)
The parking brake linkage control arm actuates the parking brake switch. The engaged switch provides 28 Vdc power to the parking brake valve motor which closes the valve.
(4)
Closing of the parking brake valve blocks return of hydraulic fluid from the brakes, energizes the brake close sense relay, and provides PARK BRAKE indication to the flight compartment.
(5)
AIRPLANES WITH A PARKING BRAKE ON LIGHT ON THE NOSE LANDING GEAR; This light on the nose gear P62 panel comes on.
(6)
The parking brake system is hydraulically powered from the right hydraulic system (AMM 29-00-00/001). When the right hydraulic system is depressurized, the accumulator supplies hydraulic pressure through the accumulator isolation valve.
(7)
The accumulator is serviced with nitrogen at the charging valve located in the lower aft body fairing hydraulic service compartment.
(8)
The parking brake is disengaged by depressing and releasing the captain's or first officer's right and left brake pedals . The spring-loaded parking brake mechanism pulls the parking brake handle down against the control stand, and disengages the parking brake switch.
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MAINTENANCE MANUAL
FIRST
OFFICERS
CAPTAINSPEDALS
PNEUMATIC
RIGHT HYD
123
04
27-20-01
PEDALS
27-20-01PRESSURE POWER
PRESS GAGE PSIX1000
APPLYBRAKES ACCUMULATOR LEFT HYD SYS
A
CHARGING
ACCUMULATOR
VALVE
ISOL VALVE
RUDDER
PEDAL INPUT
A
RUDDER
PEDAL INPUT TO NORMAL
& ALTERNATE
BRAKE
METERING
VALVE
NORMAL VALVEL AUTO
R AUTONORMAL VALVE BRAKE
BRAKESHUTTLE
SHUTTLEVALVE
VALVE
LEFTHYDLEFT
HYDSYS PARKING
SYSVALVEBRAKE
CLOSED OPENED
L ALTERNATEALTERNATE VALVE
ANTISKID CONTROL
ALTERNATE VALVE
VALVE MODULE WHEEL BRAKE
LEFT
LEFT ACTUATORWHEEL BRAKE ACTUATOR
HYD SYS
HYD SYS
R BRAKE METERINGL BRAKE METERING VALVE MODULE
VALVE MODULE
FROM
CAPTAINS
PEDALS
L NORMAL R NORMAL
R ALTERNATE
ANTISKID VALVE ANTISKID VALVE
APPLYANTISKID CONTROL
MODULE MODULE
PARK
APPLYVALVE MODULEBRAKE
BRAKESL ANTISKIDR ANTISKIDSHUTTLE VALVESHUTTLE VALVEMODULE MODULE
PARK BRAKEMETERED PRESSURE
HANDLE CABLE
SYSTEM PRESSUREPIVOT
NITROGEN
PARKING BRAKESYSTEM RETURN
LOCKING PIN
RIGHT MAIN BRAKES
BRAKE CONTROL
LEFT MAIN BRAKESPARKING BRAKECABLELOCK DETENT
A-A
Parking Brake System Hydraulic Schematic
Figure 2
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本文链接地址：757 AMM 飞机维护手册 起落架 CHAPTER 32 - LANDING GEAR 3(55)
