F.
Accumulator Isolation Valve (AIV) (Fig. 1, Detail F)

_________________________________
 (1)  The AIV is located on the right wheel well forward bulkhead, just outboard of the ABSV.
 

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 (2)  
The AIV is normally open. The AIV cycles closed to isolate the brake system accumulator when the left (alternate) hydraulic system reaches 48 percent or more of accumulator pressure. The AIV cycles to the open position when the left hydraulic (alternate) system drops to 48 percent or less of accumulator pressure to provide a backup system (accumulator) of brake pressurization.

 (3)  
The AIV and ABSV utilize the same basic valve unit. Ports connect to the brake system in a different manner to suit the different valve functions.

 G.
ALL EXCEPT GUN 051;

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 Hydraulic Brake Assembly (Dunlop Carbon Brake) (Fig. 3)

______________________________________________
 (1)  
The brake assembly is a conventional rotor-stator multiple disc unit. The brake housing is mounted on bushings which ride on main landing gear axle sleeves. A brake rod (torque arm) attaches between the lower brake housing, at a pin joint, and the yoke of the shock strut. The brake is thus allowed to rotate on the axle with corresponding landing gear truck position changes. Lubrication fittings are provided for brake rod and axle bearing joints.

 (2)  
Each brake has seven cylinder sub-assemblies. The cylinder sub-assemblies include a cylinder liner, a piston, and an automatic adjuster. Brake pressure is applied hydraulically through the pistons which push against a pressure plate. The pressure plate in turn slides axially against the stators and rotors to compress against the torque plate. When pressure is released, the brake adjuster springs pull the pressure plate back from contact with the rotor-stator stack.

 (3)  
The automatic brake adjusters are installed in each cylinder sub-assembly to automatically keep a constant pre-set clearance between the brake piston and the brake discs (rotors and stators) as wear occurs in the discs. On some brake assemblies (See Fig. 3 for effectivity), the adjuster mechanism uses a spring bushing and spacer to automatically adjust the clearance as the brake discs wear. On other brake assemblies (see Fig. 3 for effectivity) the adjuster causes a pin and ball mechanism to deform a circular tube to automatically hold the necessary clearance as the brake discs wear.

 (4)  
Two wear pins are installed in each brake assembly which indicate when brakes require replacement. The pins attach to the pressure plate by screwed housing, passing through indicator brackets which are secured to the torque plate by two screws.

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QUICK-DISCONNECT FITTING HYDRAULIC HOSE CONNECTOR
A
AXLE BUSHINGS
AND SLEEVES BLEED PLUG
TORQUE PLATE
HEAT SHIELD 
BRAKE 
SEE  A  TORQUE TUBE 
WEAR INDICATOR PIN  THRUST RING 
FWD  (2 LOCATIONS)  ASSEMBLY 
SEGMENTED 
STATOR 
(3 LOCATIONS) 
SEGMENTED 
BRAKE TIE BOLTS  ROTOR 
(10 LOCATIONS)  (4 LOCATIONS) 
BRAKE ROD  PRESSURE PLATE 
ATTATCHMENT 
POINT  CYLINDER SUB-ASSEMBLY 
A  WITH AUTOMATIC ADJUSTER 
DISCONNECT  PISTON  SEE  C 
FITTING  BRAKE  (7 LOCATIONS) 
HOUSING 
A 

INDICATORINDICATOR PIN
BRACKET NUT TORQUE
SEE B SEE B PLATE
PIN
HOUSING SCREW (2 LOCATIONS)
PRESSURE PLATE
WEAR REMAINING (BRAKE PRESSURIZED)
WEAR INDICATOR
B
A-A
Hydraulic Brake Assembly Figure 3 (Sheet 1)
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. AIRPLANES WITH DUNLOP CARBON BRAKES ú

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CYLINDER LINERTORQUE PLATE
COIL SPRING
PRESSURE PLATE
INSULATOR
PISTON
ADJUSTER
CYLINDER SUB-ASSEMBLY WITH AUTOMATIC ADJUSTER (USED ON BRAKES WITH BOEING PART NO. S160N020-14)
C
SPREADERRETAINING PLATE
　
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