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A
747-400 MAINTENANCE MANUAL
LOCK ACTUATOR
NOSE GEAR ACTUATOR
TRUNNION
HYDRAULIC LINES
DRAG STRUT
ASSEMBLY

TRUNNION PIN
SHOCK STRUT
UPPER SIDE BRACETRIPOD (2 PLACES)BRACE BULLNOSE LOWER INSTALLATION
TRIPOD
BRACE

STEERING CABLE
METERING VALVE
NOSE WHEEL WELL
CONTROL PANEL (REF)

SUMMING LEVER
UPPER
TORSION STEERING ACTUATORLINK (2 PLACES)
TORSION LINKS
APEX PIN ACTUATOR SUPPORTS (UPPER AND LOWER)
LOWER
TORSION

STEERING COLLAR
LINK
DUAL TOW
FITTING

Nose Landing Gear Component Location
Figure 1

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747-400 MAINTENANCE MANUAL
DRAG BRACE
SUPPORT BEAM

SEE B
NOSE GEAR TRUNNION SUPPORT BEAM
SEE A
FWD
Nose Gear Attachments
Figure 2 (Sheet 1)

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747-400
MAINTENANCE MANUAL

NOSE GEAR RETRACT
BELLCRANK ACTUATOR
TRUNNION
DRIVE CRANK
TRUNNION SUPPORT FITTING
TRUNNION FWD BEARING CAP
A
NOSE GEAR WHEEL WELL TOP
UPPER SUPPORT FITTING
ATTACH ROD
FWD
UPPER DRAG
STRUT

B
Nose Gear Attachments Figure 2 (Sheet 2)
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747-400
MAINTENANCE MANUAL

 4.  Nose Gear Torsion Links
_______________________
 A.  The nose gear torsion links are joined together by the torsion link apex pin at their forward ends. The upper link is connected to the forward steering collar, just below the tripod brace. The lower link connects to a set of lugs on the forward side of the inner cylinder (Fig. 1).
 B.  Steering forces applied to the steering collar by the nose gear steering cylinder are transmitted to the inner shock strut cylinder by the torsion links. The links allow rotation between the inner and outer shock strut cylinders only when moved by the steering collar, or when disconnected at their forward ends.
 5.  Nose Gear Drag Strut (Fig.____________________3)
 A.  The nose gear drag strut, in conjunction with the nose gear lock actuator, holds the nose gear in the up and locked, or down and locked position. The drag strut assembly consists of an upper strut, a lower strut, two spring bungees, left-hand upper downlock link, right-hand upper downlock link, two lower downlock links, two downlock release links, downlock crank shaft, actuator crank fitting, downlock crank fitting and a right-hand and left-hand striker bracket.
 B.  To raise the nose gear the lock actuator must retract to rotate the actuator crank fitting. The fitting then pulls the downlock release links upward. The lower end of release links are pinned to the upper downlock links. These links rotate about a shaft on the forward center of the upper drag strut. The rotational action of the upper downlock links causes the lower downlock links to compress the spring bungees. Since the lower downlock links are affixed to the upper apex of the lower drag strut and the bungee is pinned to the forward center of the lower strut, the net moment results in a force which folds the drag strut. During retraction the upper end of the upper drag strut rotates on the drag strut pivot shaft, moving upward and aft. The lower end of the lower drag strut is affixed to the tripod brace apex. As the gear retracts, the strut moves upward and aft relative to its pivot point. As the nose gear approaches fully retracted position, the drag strut assembly straightens out, the lock actuator retracts and locks the drag strut in the gear up position.
　
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