(12)
Normal operation of the uplock hook is by hydraulic fluid directed to the uplock actuator. This latches and unlatches the hook in the proper sequence as governed by the door-operated sequence valve. Provision is made to release the uplock in the absence of hydraulic pressure by means of an electrical actuator attached to the release cam. This cam contacts a follower which releases the hook. At the same time a door opening cam and follower mechanism operates the cable system which unlocks the door actuator and allows the doors to open.
(13)
When the gear is selected DN, hydraulic pressure causes the door actuating cylinder to unlock and retract. This opens the doors. The internal lock in the actuator may be mechanically unlocked by means of a rotating shaft on the cylinder end of the actuator. Rotation of this shaft unlocks the internal lock mechanism when the alternate landing gear release system is operated or when the ground door release handle is operated. Simultaneously, the door safety valve releases pressure to return. The doors are then free to fall by gravity.
B.
Control
(1)
Extension and retraction of the landing gear is controlled by moving the landing gear control handle to the UP, OFF, and DN position.
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32-33-00
ALL ú ú 04 Page 18 ú Jun 10/92
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
FAULT ISOLATION/MAINT MANUAL
BODY GEAR AND DOOR EXTENSION AND RETRACTION
COMPONENT FIG. 102 SHT QTY ACCESS/AREA REFERENCE
ACTUATOR - DOOR 2 2 L, R BODY GEAR WHEEL WELL 32-33-27
ACTUATOR - DOWNLOCK 1 2 L, R BODY GEAR 32-33-15
ACTUATOR - GEAR 1 2 L, R BODY GEAR 32-33-01
ACTUATOR - UPLOCK 2 2 L, R BODY GEAR WHEEL WELL, UPLOCK MECHANISM 32-33-14
BEAM - DOOR ACTUATOR 3 2 ACTUATOR L, R BODY GEAR WHEEL WELL, DOOR 32-33-28
BUNGEE - DOWNLOCK 1 2 L, R BODY GEAR 32-33-16
JOINT - DOOR ACTUATOR SWIVEL 3 2 L, R BODY GEAR WHEEL WELL, DOOR ACTUATOR 32-33-26
MECHANISM - DOOR OPERATED SEQUENCE VALVE 3 2 L, R BODY GEAR WHEEL WELL 32-33-02
MECHANISM - DOWNLOCK OPERATED SEQUENCE VALVE 1 2 L, R BODY GEAR WHEEL WELL 32-33-04
MECHANISM - UPLOCK 1 2 L, R BODY GEAR WHEEL WELL 32-33-08
MECHANISM - UPLOCK OPERATED SEQUENCE VALVE 2 2 L, R BODY GEAR WHEEL WELL, UPLOCK MECHANISM 32-33-07
VALVE - DOOR OPERATED SEQUENCE 3 2 L, R BODY GEAR WHEEL WELL 32-33-02
VALVE - DOOR SAFETY 3 2 L, R BODY GEAR WHEEL WELL 32-33-29
VALVE - DOWNLOCK OPERATED SEQUENCE 1 2 L, R BODY GEAR WHEEL WELL 32-33-04
VALVE - UPLOCK OPERATED SEQUENCE 2 2 L, R BODY GEAR WHEEL WELL, UPLOCK MECHANISM 32-33-06
* SEE WM EQUIPMENT LIST
Body Gear and Door Extension and Retraction - Component Index
Figure 101
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32-33-00
ALL ú
ú 01 Page 101
ú Oct 10/88
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 FAULT ISOLATION/MAINT MANUAL
SEQUENCE VALVE AND MECHANISM DOWNLOCK OPERATED
SEE B
UPLOCK MECHANISM
SEE C D SHT 2
LANDING GEAR L OR R BODY ASEE BUNGEE DOWNLOCK ACTUATOR GEAR
JURY STRUT (REF)
OUTER
CYLINDER
(REF)
DRAG STRUT
(REF) DOWNLOCK
ACTUATOR FWD
DOWNLOCK OPERATED SEQUENCE VALVE DOWNLOCK OPERATED L OR R BODY LANDING GEAR
MECHANISM SEQUENCE VALVE A
UPPER BODY GEAR JURY STRUT (REF)
KEEL BEAM
(REF)
DOWNLOCK OPERATED SEQUENCE VALVE AND MECHANISM B
Body Gear and Door Extension and Retraction - Component Location Figure 102 (Sheet 1)
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