WHEELS, BRAKES AND TIRES -NOSE LANDING GEAR WHEEL AND TIRE

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WHEELS, BRAKES, AND TIRES -NOSE WHEEL SPIN BRAKE

Purpose
Two nose wheel spin brakes use friction with the nose gear tires to stop nose wheel rotation after the nose gear enters the wheel well.
Physical Description
The wheel spin brake assemblies are on a tube in the upper forward nose wheel well. Each wheel spin brake assembly has four stainless steel cleats.
Training Information Point
The cleats on the wheel spin brake assemblies are line replaceable units.
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WHEELS, BRAKES, AND TIRES -NOSE WHEEL SPIN BRAKE

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WHEELS, BRAKES, AND TIRES -MAIN LANDING GEAR WHEEL AND TIRE

Main Landing Gear Wheels
The main wheels are radial tire wheels. They have forged inner and outer halves. Tie bolts hold the two halves together. Brake rotor drive keys and heat shields are in the inner half of each wheel.
Each wheel also has these components:
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Tire inflation valve

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Over-pressure relief valve

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Tire pressure sensor

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Thermal fuse plug (3).

Tire Inflation Valve
A tire inflation valve is in the outer wheel half.
Over-Pressure Relief Valve
An over-pressure relief valve is in the outer wheel half. The relief valve releases tire pressure above 375-450 psig.
Tire Pressure Sensor
A tire pressure sensor is in the outer wheel half. This sensor sends tire pressure data to the tire pressure indication system.
Thermal Fuse Plugs
Three thermal fuse plugs in the inner wheel half prevent tire explosion caused by hot brakes. The plugs melt to release tire pressure when their temperature is approximately 390F (199C).
Training Information Point
Radial tires install only on radial tire wheels. The radial tire wheel width between the flanges is larger than bias ply tire wheels of the same size.
You must jack both ends of the main landing gear wheel truck to remove the center wheel and tire assemblies.
The main landing gear wheels can operate with one wheel tie bolt broken or missing.
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WHEELS, BRAKES, AND TIRES -MAIN LANDING GEAR WHEEL AND TIRE

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777 AIRCRAFT MAINTENANCE MANUAL

THIS PAGE IS INTENTIONALLY LEFT BLANK

32-45-00

Page 10 D633W101-BEJ Sep 05/2002

WHEELS, BRAKES, AND TIRES -MAIN LANDING GEAR WHEEL BRAKES

General
The main landing gear wheel brakes use hydraulic pressure to slow or stop the airplane during landing and taxi.
Each main landing gear wheel brake components include:
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Stators and rotors

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Conical backing plate

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Pressure plate

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Self-adjusting piston (6)

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Axle bushing (2)

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Wear indicator pin (2)

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Brake disconnect (not shown)

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Hydraulic bleed port.

Physical Description
The brake assembly is a rotor-stator unit that operates using hydraulic pressure. The assembly uses carbon discs as rotors and stators.
The rotors and stators are compressed between the pressure plate and the conical backing plate to slow or stop the airplane.
Self-adjusting pistons apply brake system hydraulic pressure to the pressure plate. The pistons automatically adjust for brake wear.
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Two indicator pins on the inboard side of the brake housing show brake wear.
The brake units mount on bushings which ride on replaceable landing gear axle sleeves.
The center brake attachment points connect directly to the lower strut at the same place the brake rods attach. The forward and aft brake attachment points connect to the brake rods.
The brake rods transmit brake torque to the strut. They also allow brake rotation as the truck position changes.
Training Information Point
You must apply the brakes to do a check of the wear indicator pins.
The brake system can operate with one brake on each six wheel truck deactivated. Brakes may be deactivated by three methods:
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Install a flight dispatch disconnect tool in the brake position on the related antiskid shuttle valve module (This deactivates normal braking only. Alternate braking is still available.)
　
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