NOSE GEAR STEERING SYSTEM -NLG STEERING BROKEN CABLE COMPENSATOR
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NOSE GEAR STEERING SYSTEM -NLG STEERING PIVOT LINK AND NLG STEERING CENTERING MECHANISM
Purpose
The NLG steering pivot link connects the upper cable loop to the lower cable loop.
The NLG steering centering mechanism locks the NGS system in the centered position during gear retraction.
Physical Description
The hinged pivot links connect the output shaft of the NLG steering broken cable compensator to the NLG steering centering mechanism.
The NLG steering centering mechanism has these components:
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Spring cartridge
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Crank and shaft
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Driver
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Guide link
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Cam assembly
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Cam follower
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Drum.
Location
The NLG steering centering mechanism is on top of the nose landing gear.
Functional Description
When the nose gear starts to retract, the movement of the nose gear lock link moves the spring cartridge.
The spring cartridge turns the shaft through the crank. This lifts the driver and cam assembly.
The driver and cam assembly moves the cam follower to the centered position. This moves the upper and lower cable loops to the neutral position.
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NOSE GEAR STEERING SYSTEM -NLG STEERING PIVOT LINK AND NLG STEERING CENTERING MECHANISM
EFFECTIVITY BEJ ALL 32-51-00
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NOSE GEAR STEERING SYSTEM -NLG STEERING SUMMING MECHANISM AND METERING VALVE MODULE
General
The NLG steering summing mechanism adds steering tiller input and nose gear position feedback to control the NLG steering metering valve module.
The NLG steering metering valve module controls the flow of hydraulic fluid to the NLG steering actuators.
The summing mechanism is on top of the upper steering plate on the front of the nose gear. A protective cover is on the summing mechanism.
The NLG steering metering valve module is on the upper steering plate on the front of the nose gear shock strut.
NLG Steering Summing Mechanism
The NLG steering summing mechanism contains these components:
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Summing lever
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Pulley (2)
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Input rod.
The pulleys connect to each side of the summing lever. The lower cable loop winds around each pulley.
EFFECTIVITY
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The summing mechanism pivots about its center. The input rod connects the summing mechanism to the metering valve module.
NLG Steering Metering Valve Module
The NLG steering metering valve module contains these components:
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Metering valve
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Dynamic load damper
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Bypass/relief valve (not shown)
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Compensator
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Towing shutoff valve and lever
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Swivel valve (2).
The metering valve controls hydraulic flow to the steering actuators. The valve is spring-loaded to the centered position.
The dynamic load damper supplies shimmy damping to the nose gear.
The bypass/relief valve protects the steering actuators against high hydraulic pressures. When pressure in an actuator goes above 4000 psi, the bypass/relief valve opens and permits hydraulic fluid to move between the actuators.
The compensator keeps a 250 psi backpressure in the steering metering valve module. This prevents steering actuator cavitation during shimmy damping.
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NOSE GEAR STEERING SYSTEM -NLG STEERING SUMMING MECHANISM AND METERING VALVE MODULE
A towing lever on the metering valve module controls a towing shutoff valve. In the tow position, the towing valve shuts off pressure to the nose gear steering system. This permits the nose gear to turn during towing. A towing lever pin holds the towing lever in the TOW position.
The swivel valves control hydraulic flow to the two sides of the steering actuators.
Functional Description
Tiller operation moves the summing mechanism from the neutral position. This makes an input to the metering valve module which sends pressure to the NLG steering actuators. The NLG steering actuators turn the nose gear.
The rotation of the nose gear moves the summing mechanism back towards the neutral position. When the nose gear position agrees with the tiller position, the summing mechanism moves the metering valve to the neutral position. This shuts off the flow to the NLG steering actuators.
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