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 2.  Steering Tiller and Cable Drum (Fig. 1)______________________________
 A.  The steering tillers are located on the sidewalls to the left of the pilots position and to the right of the first officers position. Steering tillers are used to turn the nose gear a maximum of 70 degrees. The cable drum transfers movement of the tillers to the steering cables.
 3.  Rudder Pedal Steering Mechanism (Fig. 2)
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A
747-400
MAINTENANCE MANUAL

RUDDER 
PEDALS 
ELECTRIC  SEE  A 
ACTUATORS 
TILLER 

SEE B
SUMMING 
QUADRANT LEVER 
RUDDER INTERCONNECT 
MECHANISM 

NOSE GEAR
A
STEERING CABLE COMPENSATOR
METERING ASSEMBLY
VALVE STEERING CYLINDER SQUAT SWITCH
TRUNNION LINK  LINK BULKHEAD  (BODY GEAR STEERING) COMMAND TRANSDUCER 
TRUNNION PIVOT LINKS 
B 
Nose Gear Steering System Component Location Figure 1 

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747-400
MAINTENANCE MANUAL

RUDDER QUADRANT TENSION REGULATOR RETURN SPRING
STEERING ROD
ALTERNATE ELECTRIC ACTUATOR
Rudder Pedal Steering Mechanism
Figure 2

RUDDER PEDAL INTERCONNECT QUADRANT
STEERING
ARM
STEERING CRANK
PRIMARY ELECTRIC ACTUATOR
ACTUATOR LEVER
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747-400
MAINTENANCE MANUAL

 A.  The rudder pedal steering mechanism consists of a rudder interconnect quadrant, a steering rod, steering crank, steering arm, actuator lever and two electric actuators. When the nose gear is compressed, the electrical ground sensing system enables rudder pedal steering to be utilized.
 4.  Steering Metering Valve (Fig. 1)
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 A.  The steering metering valve is a slide and sleeve type valve located on the nose gear. Combined with the metering valve are a pair of swivel valves to direct hydraulic fluid for turns. The slide and sleeve assembly is ported to direct 3000-psi hydraulic fluid through the swivel valves to the steering actuators.
 B.  The steering metering valve incorporates a spring compensator to maintain a pressure of 205 to 325 psi against the actuator pistons to act as a shimmy damper. On some airplanes, the spring compensator maintains a pressure of 50 to 130 psi against the actuator pistons. The valve structure includes a bypass check valve to allow flow of hydraulic fluid between ports to prevent cavitation. A bypass valve protects steering system from high pressures developed in steering actuators during towing. With the steering hydraulic system depressurized, residual pressure, coupled with small frictional forces within the valve, act to retain the bypass valve in closed position.
 5.  Steering System Cables (Fig. 1)
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 A.  There are four functional sets of cables which make up the Nose Wheel Steering System. Two upper sets consist of 3/32-inch diameter carbon steel cables which run from the steering tillers to the nose shock stuck trunnion pivot link. These two set are designated NWS1A and NWS1B. Two lower sets consist of 3/32-inch steel cables which run from the trunnion-mounted pivot link down to the steering metering valve. These two sets are designated NWS2A and NWS2B. The lower sets have a cable (ball attached near it's center point) that is common to both sets.
 6.  Nose Gear Steering Actuators (Fig. 3)
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