THE WORN PART CAN BE REPAIRED. REFER TO THE OVERHAUL MANUAL FOR THE REPAIR PROCEDURE.
DISTANCE BETWEEN THE INNER EDGE OF THE OUTER BUSHING FLANGES.
DISTANCE BETWEEN THE OUTER EDGE OF THE INNER BUSHING FLANGES.
DISTANCE (BOLT GRIP LENGTH) BETWEEN THE LEAD AND THE SHOULDER OF THE BOLT PLUS A POSSIBLE
1/6 TURN BACKOFF OF THE NUT.
DISTANCE BETWEEN THE OUTER EDGE OF THE INNER FLANGES OF THE BUSHINGS IN THE INNER CYLINDER OF THE
SHOCK STRUT.
DISTANCE BETWEEN THE OUTER EDGES OF THE BRAKE TORQUE ARM BUSHINGS.
THE MAXIMUM DIMENSION CAN BE MORE THAN THE LIMITS SHOWN IF THE MAXIMUM CLEARANCE IS SATISFACTORY.
APPLICABLE TO THE WING GEAR ONLY.
APPLICABLE TO THE BODY GEAR ONLY.
Wear Limits for the Brake Rod
Figure 601 (Sheet 2)
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400 MAINTENANCE MANUAL
PARKING BRAKE SYSTEM - DESCRIPTION AND OPERATION
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General
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A. A parking brake system is provided to permit setting the brakes during parking and mooring. The system consists of a parking brake lever on the control stand which operates an electrical switch and an electrical motor operated parking brake module. The parking brake operates on the normal brake system only and can be set only when hydrualic system 4 is pressurized.
B. The parking brakes may be set by either the captain or the first officer. A PARKING BRAKE SET indication will come into view on EICAS when the parking brake is set. Setting the parking brake enables the erase circuit in the voice recorder system, AMM 23-71-00/501.
Parking Brake Lever and Linkage (Fig. 1).
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A. The parking brake lever is located on the left side of the flight deck center console. It is connected to the parking brake linkage which consists of shafts, levers, connecting rods, a tube assembly and pawls. When one of the flight crew push the brake pedals to the stops and pull the parking brake lever, the pawls in the linkage are rotated to engage a shaft on the brake pedal bell crank. This holds the brakes in the applied position.
Parking Brake Indication (Fig. 2)
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A. Parking brake indication is shown on the EICAS on the P2 panel. When the parking brake lever is pulled, the movement of the linkage sets a micro switch. This passes power from the PARK BRAKE circuit breaker on the P6 panel to the close fields of the electric motor on the parking brake module. When the electric motor has cycled to the closed position, power and ground are provided to turn on the Parking-Brake-Valve-Closed Relay. When the relay switches it establishes a path from the electrical interface units (EIUs) to ground, and this permits the PARKING BRAKE SET indication to appear on EICAS.
B. When the relay switches, it also provides a ground through the S313 Parking Brake Lever Switch to turn on the BRAKE ON light on the P37 panel.
C. When the relay switches, it also provides a ground to turn on the PARK BRAKE SET light (L1539) on the P37 panel.
D. There are three lights located on the P37 panel which are used to monitor the status of the parking brake system. These lights include the following:
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PARK BRAKE SET (Amber - L1539)
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