E. The filter is installed adjacent to the brake port and prevents contamination in the fluid from the brakes from entering the moving components of the valve.
F. If it becomes necessary to dispatch an airplane with a brake that should be disabled, the brake can be disconnected at the shuttle valve. This is done with a flight dispatch plug (A32080-1, brake disconnect tool). The shuttle valve cap associated with the brake to be disabled is removed and the plug installed. The plug pushes the slide in the valve to the alternate position. This prevents the brake from operating when the normal brake system is pressurized. The brake will operate when the alternate brake system is pressurized during gear retraction or during a failure of the normal brake system.
7. Pressure-Compensated-Flow Regulator (Fig. 5)
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A. A pressure-compensated-flow regulator is installed between the brake port of the antiskid shuttle valve and the brake of each wheel. One is installed on each brake port of the body-gear-antiskid-shuttle-valve assembly, and one is installed in each brake hydraulic line above the truck on the wing gear.
B. The pressure-compensated-flow regulator prevents the flow of fluid to the brakes from increasing to more than 1.0 gpm when pressure upstream of the regulator is between 100 psi and 3000 psi. Flow in the opposite direction is passed at a minimum rate of 4 gpm when the brakes are released. The pressue-compensated-flow regulator prevents pressure in the brakes from increasing too quickly at the beginning of brake operation.
C. A malfunction of a pressure-compensated-flow regulator cannot be easily found when the regulator is installed in the airplane. A test can be done on a regulator after it is removed from the airplane. The maintenance manual does not contain a removal and installation procedure for pressure-compensated-flow regulators because the steps are not different from usual hydraulic line servicing procedure.
8. Autobrake Control Panel (Fig. 6)
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A. The autobrake control panel is installed on the center console on the flight deck. It contains a rotary selector switch which is used to turn on the autobrake system. The switch has these positions:
-OFF
-DISARM
-
Position 1
-
Position 2
-
Position 3
-
Position 4
-MAX AUTO
-RTO
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
FLIGHT COMPARTMENT
AUTOBRAKES
2
DISARM
4
MAXOFF AUTO
AUTOBRAKE SELECTOR SWITCH
A
Autobrake Control Panel - Location
Figure 6
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
B. When the switch is in the OFF position, power is not available to the autobrake system. The flight crew may move the switch to the OFF or DISARM position to change to manual braking, but this is usually done by operating the brake pedals. The switch will turn to the DISARM position from any position other than OFF when a malfunction of the antiskid system or the autobrake system occurs. The switch is moved to the RTO position to arm refuse take off before a takeoff roll. This position is used only when the airplane is in the ground mode.
C. To move the switch from DISARM to OFF or from OFF to DISARM you must push in on the switch before turning it.
D. All switch positions other than OFF and DISARM are used to make a deceleration rate selection. The rates are shown in the table below.
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Application Autobrake Delay Deceleration Maximum Brake Selection in Seconds* Ft/Sec. Pressure, PSI
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1 0.2 4.0 1500
2 0.2 5.0 1750 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747-400 AMM 飞机维护手册 起落架 LANDING GEAR 6(130)
