C. Steering Actuating Cylinder
 -Piston diameter: 79.25 mm
 -Internal stop for plus or minus 95 deg. wheel travel i.e. a stroke of plus or minus 123 mm.
 -Maximum flow: 7.55 l/mn which corresponds to a steering speed of 18 deg./s (at no load)
 D. Selector Valve
 -Power supply: 18 to 30VDC
 -Max. power consumption: 0.8A at -40 deg.C
 E. Servovalve
 (Ref. Fig. 015)
 This valve is of the deflection-jet type.

 -Nominal flow: 26 l/mn under 206 bars for I = 8 mA.
 -Coils in parallel - Internal leakage: 0.9 l/mn
 -LVDT sensor: Power supply: 26 V -400Hz Input current: 14.5 mA Sensitivity: 40 mV/mm/V Stroke: plus or minus 0.6 mm (stroke of the slide valve of the servovalve plus or minus 0.5 mm).
 F. Speed Adjustment Diaphragm
 -Diameter: 1.3 mm for a steering speed of 18 deg./s at no load.
 G. Anti-Shimmy Accumulator
 -Maximum capacity: 80 cubic centimeters
 -
Pressure at max. capacity: 15 bars

 -
Pressure at zero capacity: 7.5 bars.

 1EFF : 001-049, 051-099, 101-149, 151-199, 1 32-51-00Page 26 1201-299, 301-399, 1Config-1 Aug 01/05 1 1 1CES 1

 Nose Wheel Steering - Handwheel Transmitter Unit
 Figure 013

 1EFF : 001-049, 051-099, 101-149, 151-199, 1 32-51-00Page 27 1201-299, 301-399, 1Config-1 Aug 01/05 1 1 1CES 1

 Nose Wheel Steering - Wiring
 Figure 014

 1EFF : 001-049, 051-099, 101-149, 151-199, 1 32-51-00Page 28 1201-299, 301-399, 1Config-1 Aug 01/05 1 1 1CES 1

 Servovalve
 Figure 015

 1EFF : 001-049, 051-099, 101-149, 151-199, 1 32-51-00Page 29 1201-299, 301-399, 1Config-1 Aug 01/05 1 1 1CES 1 H. Feedback Sensor

 -Reduction gearbox:
 Reduction ratio: 0.46.
 Automatic take-up of play by spring.
 Shock-mounted on the nose gear strut.

 -RVDT sensor: Inductive potentiometer with shifted windings, supplied with 26 V 400Hz obtained from transformation of 115 V from AC BUS 1 through the BSCU system 1. Linearity range: plus or minus 35 deg. Linearity consumption: 60 mA -0.6 W.
 J. BSCU (Ref. 32-42-00)
 5. Operation/Control and Indicating
________________________________
 A. The hydraulic pressure is sent to the hydraulic block when the nose gear is extended and when its doors are closed. (This means that after a free-fall extension of the gear, when the doors normally remain open, the steering control is lost).
 B. On the ground, when you open the NLG doors with the Ground Door-Opening Handle the steering is still operational. On the ground the energization of the selector valve causes the pressurization of the hydraulic block. This is done under the conditions below :
 -towing control lever in the normal position,
 -at least one engine in operation,
 -shock absorber compressed,
 -aircraft speed lower than 80 kts.
 C. In flight, as soon as the gear is extended for landing, the test of the steering control is made. In this case, the energization of the selector valve occurs under the conditions below :
 -towing control lever in the normal position,

 -at least one engine in operation,

 -shock absorbers of the main landing gears extended.
 The test starts 10 seconds after the nose gear is downlocked and stops
 upon touchdown of the main gears.
 In this test, an electrical signal is temporarily sent to the servovalve,
 thus causing a slight motion of the nose wheel assembly (less than 2
 degrees).
 The monitoring channel checks that the order has been correctly executed.

 D. The operation of the BSCU is described in 32-42-00.
 1EFF : 001-049, 051-099, 101-149, 151-199, 1 32-51-00Page 30 1201-299, 301-399, 1Config-1 Aug 01/05 1 1 1CES 1

 E. On the nose gear leg, when the towing control lever is in the towing position, the MEMO section of the upper ECAM DU shows "NW STRG DISC" in green. This message is amber if one engine is running.
 F. Operating Principle (Ref. Fig. 016) The control channel acts on the servovalve as a function of the difference in position between the handwheel (in the cockpit) and the wheels. The monitoring channel delivers in a similar manner a signal which represents the position of the slide valve in the servovalve. If both channels disagree about the position of the slide valve in the servovalve, the steering system is depressurized. The principle is the same when the control is either made through the pedals or in automatic mode.
 G. Aircraft Turning Radii
 **ON A/C 001-049, 051-099, 101-149, 201-299,
　
中國航空網 www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：A320飛機維護手冊 AMM LANDING GEAR 起落架8(71)