*
Antiskid shuttle valve module (1)
*
Normal antiskid valve module (1)
*
Alternate antiskid valve module (1).
The autobrake system automatically applies the brakes to stop the airplane during landing or a rejected takeoff.
Autobrake components for the airplane include:
*
Autobrake selector (1)
*
Normal brake metered pressure transducer (2)
*
Alternate brake metered pressure transducer (2)
*
Autobrake valve module (1)
*
Autobrake shuttle valve (2).
The brake system control unit (BSCU) controls antiskid and autobrake operation.
Inputs
The BSCU uses these inputs to control antiskid and autobrake operation:
*
Truck tilt (PSEUs)
*
Landing gear lever position (PSEUs)
*
Air and inertial data (ADIRU)
*
Speedbrake lever position (PFCs)
*
Thrust lever position
*
Parking brake valve position
*
Parking brake lever position
*
Right hydraulic system pressure
*
Alternate brake system pressure
*
Normal and alternate metered brake pressure
*
Wheel speed
*
Autobrake selector position.
Normal Antiskid Operation
The normal brake metering valves send metered pressure from the right hydraulic system or the accumulator through the autobrake shuttle valves to the normal antiskid valve modules. The BSCU sends signals to the normal antiskid valve modules to control the metered pressure to each brake. The metered pressure goes through the antiskid shuttle valve modules to the brakes.
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ANTISKID/AUTOBRAKE SYSTEM -GENERAL DESCRIPTION
An antiskid surge accumulator absorbs pressure surges in the return lines from the left normal antiskid valve module. The pressure surges can occur during antiskid operation. It is not necessary for the right normal antiskid valve to have a surge accumulator since it is near the right system reservoir.
Alternate Antiskid Operation
The alternate brake metering valves send metered pressure from the center hydraulic system to the alternate antiskid valve modules. The BSCU sends signals to the alternate antiskid valve modules to control the metered pressure to each aft brake and to forward-middle brake pairs. The metered pressure goes through the antiskid shuttle valve modules to the brakes.
Autobrake Operation
The BSCU sends signals to the autobrake valve module to control autobrake pressure to the normal brake system.
The autobrake valve module meters right hydraulic system pressure to the brakes. The autobrake pressure goes through the autobrake shuttle valves, the normal antiskid valves, and the antiskid shuttle valves.
The normal antiskid operates during autobrake operation.
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ANTISKID/AUTOBRAKE SYSTEM -GENERAL DESCRIPTION
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ANTISKID/AUTOBRAKE SYSTEM -COMPONENT LOCATIONS
General
These are the antiskid/autobrake system components:
*
Autobrake selector
*
Antiskid transducer (12)
*
Brake system control unit (BSCU)
*
Normal brake metered pressure transducer (2)
*
Autobrake shuttle valve (2)
*
Autobrake valve module
*
Antiskid shuttle valve module (2)
*
Normal antiskid module (2)
*
Alternate antiskid module (2)
*
Alternate brake metered pressure transducer (2).
Autobrake Selector
The autobrake selector is on the P2 center forward panel below the landing gear control lever.
Antiskid Transducer
There is an antiskid transducer for each main landing gear wheel in the each axle.
Brake System Control Unit (BSCU)
The BSCU is on the E6 rack in the aft cargo compartment.
Normal Brake Metered Pressure Transducer
The normal brake metered pressure transducers are on the
autobrake shuttle valves in the left and right main wheel wells.
Autobrake Shuttle Valve
Autobrake shuttle valves are in the left and the right main gear wheel wells on the forward walls inboard of the brake metering valves.
Autobrake Valve Module
The autobrake valve module is on the keel beam in the forward section of the right main wheel well.
Antiskid Shuttle Valve Module
Antiskid shuttle valve modules are outboard of the main landing gear trunnions. They are below the normal antiskid modules.
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