SEE B SEE A
MANIFOLD ASSEMBLY
DIRECT-READING PRESSURE GAGE VALVE GAS CHARGING INBD
FWD
HYDRAULIC-PRESSURE-SURGE ACCUMULATOR RIGHT-WING-WHEEL WELL STATION 1334 A WING-GEAR-HYDRAULIC-PRESSURE-SURGE ACCUMULATOR INSTALLATION DIRECT-READING-PRESSURE GAGE
GAS CHARGING VALVE
CHARGING INSTRUCTION CHART
BODY-GEAR-HYDRAULIC-PRESSURE-SURGE ACCUMULATOR INSTALLATION
B
Hydraulic-Pressure-Surge-Accumulator Component Location
Figure 7
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D. A gas charging valve and a direct-reading-pressure gage are adjacent to each hydraulic-pressure-surge accumulator. These are used in servicing procedures.
E. The hydraulic-pressure-surge accumulators are installed and removed using procedures in this section. They are filled with gas under pressure in Hydraulic Pressure Surge Accumulator - Servicing (AMM 12-15-11/301).
13. Operation (Fig. 8)
_________
A. Functional Description
(1)
The Normal Brake System
(a)
Hydraulic system 4 must be pressurized to operate the normal brake system. Hydraulic system 4 pressure is applied to the normal brake metering valves and pressurizes the hydraulic brake accumulator. This pressurizes the brake-system-pressure transmitter connected to the gas side of the hydraulic brake accumulator and causes the HYD BRAKE PRESS gage on the captain's instrument panel to show approximately the same pressure as hydraulic system 4 indication on EICAS.
(b)
When the brake pedals are pushed the brake-pedal-bus-crank assembly turns. This moves a control quadrant connected to the bus and operates the brake cables. The brake cables operate the brake metering valves to release hydraulic fluid into the brake lines. Since both the normal and alternate-brake-metering valves are connected to the same lever in the control quadrant, both valves will open, but hydraulic pressure will be available only to the normal brake system because the alternate-source-selector valves prevent fluid from getting to the alternate-brake-metering valves.
(c)
The fluid moves through the autobrake shuttle valves, antiskid valves, hydraulic fuses and antiskid shuttle valves (AMM 32-42-00/001) to the brakes. Hydraulic pressure increases against the pistons in the brake carrier until they begin to move and compress the brake heat stack.
(d)
When the brake pedals are released, the brake metering valves release pressure in the brake lines to hydraulic system 4 return lines. The brake pistons move back under the force of the return springs and push hydraulic fluid back into the return lines.
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Hydraulic Brake System Schematic
Figure 8 (Sheet 1)
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ANTI-SKID SURGE ACCUMULATORANTI-SKID -BRAKES SURGE OFF (EXAMPLE)ACCUMULATOR
LEFT WING GEAR GEAR LEFT BODY RIGHT BODY BODY GEAR RIGHT WING
RETURN PRESSURE
BRAKE SYSTEM ACCUMULATORS Hydraulic Brake System Schematic Figure 8 (Sheet 2)
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