-
Port "B" is connected to the brake pressure lines of the alternate-source-selector valves.
-
Port "R" is connected to the switch port.
-
The port marked "BRAKE" is connected to the pressure port of the normal-brake-metering valves.
D.
With full pressure on hydraulic system 4, 1 and 2, system 4 pressure at port A of the accumulator isolation valve holds it in the open position. This supplies hydraulic system 4 pressure to the normal brake metering valve. When hydraulic system 4 pressure is removed, pressure from either alternate-source-selector valve brake-pressure port is put on the accumulator isolation valve at port B. This closes the accumulator isolation valve. With the valve closed the accumulator cannot release fluid into the normal brake system when the brakes are operated.
E.
When pressure is removed from hydraulic system 1, 2 and 4, pressure from the brake accumulator opens the accumulator isolation valve. This permits the accumulator to pressurize the normal brake system when the parking brake is set.
F.
This valve is removed and installed using a procedure in this section. A test on the valve is done in the Hydraulic Brake System - Adjustment/Test (AMM 32-41-00/501).
7. Hydraulic Brake Accumulator (Fig. 4)
___________________________
A. One hydraulic brake accumulator is installed in the airplane. In subsequent steps, the hydraulic brake accumulator is referred to as the accumulator.
(1)
The accumulator supplies hydraulic pressure to operate the parking brake system. It also absorbs pressure fluctuations in the brake system and makes sure that hydraulic pressure is supplied to the brakes immediately when the brake pedals are operated.
(2)
The accumulator is installed on the keel beam in the wheel well for the right body gear.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400
MAINTENANCE MANUAL
A
Hydraulic Brake Accumulator - Component Location
Figure 4 (Sheet 1)
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
C15126
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MAINTENANCE MANUAL
SEE B
ALTERNATE BRAKE RETURN VALVE INSTALLATION
HYDRAULIC LINE
HYDRAULIC BRAKE ACCUMULATOR
PRESSURE GAGE BRAKE SYSTEM PRESSURE TRANSMITTER
ACCUMULATOR
GAS CHARGING
VALVE
B
Hydraulic Brake Accumulator - Component Location Figure 4 (Sheet 2)
C15141
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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MAINTENANCE MANUAL
(3)
The accumulator is a steel cylinder with a cap on each end. A piston inside the cylinder divides it into two chambers. One contains gas and the other hydraulic fluid. The end caps have ports. The port on the gas side of the accumulator is connected to a charging valve. The port on the fluid side is connected to hydraulic system 4, just upstream of the normal brake metering valves.
(4) 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(19)