D.
Restore Airplane to Normal

 S 094-013
 WARNING:_______OBEY THE REMOVAL PROCEDURE FOR THE DOOR LOCKS. THE DOORS OPEN AND CLOSE QUICKLY. THE MOVEMENT OF THE DOORS CAN CAUSE INJURIES TO PERSONS AND DAMAGE TO EQUIPMENT.
 (1)
Remove the body gear door locks (AMM 32-00-30/201).

 S 844-014

 (2)
Remove hydraulic pressure No. 1 and 4 (AMM 29-11-00/201).

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 32-36-08
 ALL  ú ú 03 Page 407 ú Oct 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 WHEELS AND BRAKES - DESCRIPTION AND OPERATION
_____________________________________________
 1.  General
_______
 A.  During takeoff, landing or ground operations the airplane moves on 18 wheels. Four wheels are installed on each wing gear truck, four wheels are installed on each body gear truck, and two wheels are installed on the nose gear. Each wheel contains a tubeless tire. The tires are inflated with dry nitrogen (AMM 12-15-06/301).
 B.  Each wing and body gear wheel is installed over a brake. The brake is a multidisk type with carbon heat stacks that can be replaced during brake overhaul. Hydraulic system 4 supplies hydraulic pressure to the brakes for normal operation. Hydraulic system 1 or hydraulic system 2 supplies hydraulic pressure to the brakes for alternate operation (AMM 32-41-00/001).
 C.  A brake control system is installed to protect the airplane from skid and brake overtorque when the brakes operate. The system also contains automatic braking to permit the flight crew to operate the brakes without operation of the foot pedals. This is an electrical feedback system with digital signal processing. It contains test circuits that permit a system malfunction to be isolated to any line replaceable unit (AMM 32-42-00/001).
 D.  A parking brake system holds the airplane in position when it is parked and hydraulic pressure is removed. The system contains linkage that holds the brakes in the applied position with pressure from a hydraulic brake accumulator. Electrical switches and relays supply parking brake indication to EICAS (AMM 32-44-00/001).
 E.  A brake temperature monitoring system supplies brake temperature indication to the flight crew. The system uses thermocouple sensors installed in each brake. These supply an electrical signal that is changed to a digital signal and supplied to the flight deck for display on EICAS (AMM 32-46-00/001).
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 32-40-00
 ALL  ú ú 04 Page 1 ú Feb 10/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 HYDRAULIC BRAKE SYSTEM - DESCRIPTION AND OPERATION
__________________________________________________
 1.  General_______
 A.  The hydraulic brake system helps to control the airplane during ground operations. It supplies these functions:
 -Hold the airplane during parking, mooring and engine runup
 -Stop the wheels from turning after takeoff
 -Decrease the length of the landing run
 -
Help to turn the airplane when it taxies.

 B.  
Hydraulic brake system is divided into a normal and a alternate system. Hydraulic system 4 supplies pressure for the normal brake system. When pressure from hydraulic system 4 is not available, hydraulic system 1 automatically supplies pressure to the alternate brake system. If pressure from hydraulic system 4 and hydraulic system 1 is not available is not available, hydraulic system 2 pressurizes the alternate brake system. The alternate system is pressurized only when pressure is not available to the normal system.

 C.  
Brakes are installed on all 16 main wheels. There are no brakes on the nose wheels. An antiskid system supplies skid control for each wheel/brake independently. An automatic braking system is available. When it is turned on it will operate the brakes without manual input from the flight crew. A brake torque control system protects the landing gear from damage caused by too much brake force which can occur under certain conditions when carbon brakes are used. For more information on antiskid, autobrake and brake torque control refer to AMM 32-42-00/001.
　
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