747-400 AMM 飞机维护手册 起落架 LANDING GEAR 7(177)

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 A.  The nose wheel steering actuators are double acting hydraulic piston and cylinder assemblies, using external fluid transfer tubes to effect a double acting arrangement. Mounting trunnions on the steering actuators are attached between steering plates fixed to the outer cylinder of the shock strut. Bearings in the steering plates allow full swiveling action of the steering cylinders. Hydraulic oil passages are provided within the trunnions, to mate with oil passages in the metering valve mounted directly above the steering cylinders. Close tolerance bolts and faying surface packings are provided around the oil passages to provide a fluid tight connection.
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747-400
MAINTENANCE MANUAL

NOSE GEAR STEERING ACTUATOR
SQUAT SWITCH SENSOR ACTUATOR
Nose Gear Squat Switch
Figure 3

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747-400
MAINTENANCE MANUAL

 7.  Nose Gear Steering Collars
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 A.  Nose gear steering collars are bolted together around the shock strut outer cylinder. An annular recess is provided between upper and lower support lugs on the strut, just below the tripod attach lugs. The steering collar is split in two halves. Forward steering collar contains the upper torsion link attach lug. Aft collar steering actuator attach lugs slip over the forward collar lugs. The two sections are locked together on each side by actuator attach pins. These pins also hold the rod end of the steering actuators. The forward steering collar contains the steering angle indicator. The zero calibration on angle indicator coincides with slot on collar bushing, so that nose wheel steering angle may be directly read on indicator.
 8.  Rudder Pedal Interconnect Actuators (Fig. 2)
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 A.  Rudder pedal steering is engaged when the nose gear is compressed by two interconnect actuators. The No. 1 electric actuator retracts and the No. 2 electric actuator extends to engage the steering mechanism to the rudder pedals.
 9.  Cable Compensator (Fig. 1)
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 A.  The cable compensator assembly has two cable drums interconnected by a butterfly cam and roller mechanism. Under normal operation the two drums act as one. In the event of a failed cable, the compensator acts to prevent a false input to the steering metering valve. This is done by the action of the roller moving out of its detented position if tension becomes relaxed on one side of the cable drum.
 10. Pivot Link (Fig.1)
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 A.  Two pivot links interconnect the shaft of the cable compensator with the cables that input to the steering metering valve. This linkage allows for extension and retraction of the nose gear without interference to the cable system.
 11. Metering Valve Compensator
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 A.  The metering valve compensator maintains a pressure of 205 to 325 psi against the steering actuator pistons to act as a shimmy damper.
 12. Nose Gear Steering Actuators Supports
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 A.  The actuator supports attach to the aft side of the shock strut outer cylinder, just below the tripod attach lugs. The lower actuator support is a wing-shaped forging, with circular mounts at each end to support the steering actuator trunnions. The upper actuator support is identical to lower, except that it has four additional lugs on the trailing edge for metering valve support attachment.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 13. Operation
　
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