A
Spring Cartridge and Piston Position Quadrant Mechanism Figure 5
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SEEA
METERING VALVE MODULE SUPPORT BRACKET
NWSA CABLE COMPENSATOR SHAFT
A
SEE B
RIGHT
COMPENSATOR
LINK
RIGHT A
SUMMING
LEVER SUMMING LEFT NWSB
LEVER
LEFT
COMPENSATOR LINK
(WITH COVER REMOVED)
A
Summing and Broken Cable Compensator Mechanism Figure 6 (Sheet 1)
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MAINTENANCE MANUAL
CABLE PULLEY
BRACKET
(2 PLACES)
CABLE PULLEY (2 PLACES) RIGHT SUMMING LEVER SPLINED SHAFT SUPPORT BRACKET LEFT
SUMMING
LEVER
BUSHING LEFT
LINK
B COMPENSATOR CAM
B
VALVE VALVE
INPUT ROD RIGHT
INPUT LINK
LEVER SUPPORT BRACKET A-A
CABLE COMPENSATOR CAM
LEVER LEVER RIGHT LINK
LEFT LINK
ROLLER B-B
METERING VALVE MODULE
STEERING INPUT CONTROL ROD
BOLT
NS5 RIGGINGMETERING VALVE
PIN HOLE
INPUT ARM
B
Summing and Broken Cable Compensator Mechanism Figure 6 (Sheet 2)
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MAINTENANCE MANUAL
SEE A
METERING VALVE MODULE UPPER SHOCK
STRUT (REF)
SWIVEL VALVE
(2 LOCATIONS)
UPPER TORSION LINK (REF)
TOWING
LOWER TORSION LEVER LINK (REF)
UPPER SUPPORT PLATE (REF)
STEERING COLLAR
ROD END BOLT
LOWER SUPPORT PLATE (REF)
LOWER SHOCK STRUT (REF)
STEERING ACTUATOR FWD (2 LOCATIONS)
(SHOWN WITH SUMMING MECHANISM COVER REMOVED)
A
Steering Metering Valve Module and Actuator Mechanism
Figure 7 (Sheet 1)
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MAINTENANCE MANUAL
(2) The metering valve is mechanically controlled by linkage from the
summing bar which detects any error angle between the steering
collar on the nose gear shock strut and tiller position.
(3) Valve centering springs ensure that the valve spool remains centered
when tension is lost in the control cables.
(4) The swivel valves channel hydraulic fluid to the actuator. The
swivel valves function to prevent one actuator from working against
the other when it passes over center at a steering angle of greater
than 30 degrees.
(5) The metering valve module has a bypass valve which interconnects the
two actuator chambers when inlet pressure is removed or when
pressure at either cylinder port exceeds 3900 psi with the inlet
pressure at 2900 psi. The bypass valve is a conventional pressure
operated shuttle valve with large operating forces. A spring loaded
compensator maintains 250 psi back pressure on the steering system.
This prevents cavitation in the actuators in the event of shimmy and
provides fluid for a hydraulic power off landing.
SWIVEL
LEFT
VALVES
STEERING COLLAR
NOSE WHEEL STRAIGHT
NOSE WHEEL IN LEFT
AHEAD
TURN AT 0` TO 30`
STEERING ACTUATOR OPERATION SCHEMATIC
Steering Metering Valve Module and Actuator Mechanism Figure 7 (Sheet 2)
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(6)
A shimmy damping valve, called a dynamic load damper (DLD) is an integral part of the steering metering valve. The valve is a combination of orifices, oil volumes, and spring which provides a dynamic filter circuit for spool motion to reject low frequency actuator pressure variations, but to recognize high frequency pressure variations which will occur if any shimmy conditions exists. The valve will then meter damping flow across the actuators. Bleed orifices from supply to the dynamic load damper (DLD) provide continuous purging flow and fill the compensator with fluid when the gear is extended.
(7)
A towing lever is provided on top of the valve package. Pulling the towing lever will first move the shut-off valve to block supply pressure to the valve package and then shift the DLD spool to port fluid across the steering actuators. The lever is spring loaded and must be held in towing position with a pin type tool.
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