Device for the conversion of the linear movement of a movably mounted in a cylinder piston in the rotational movement of a wheel holder with landing wheel of a vehicle frame leg of an aircraft

摘要

1,122,563. Steering aircraft nosewheels. HAWKER SIDDELEY DYNAMICS Ltd. 9 Aug., 1965 [11 Aug., 1964], No. 32717/64. Heading B7H. A steerable aircraft nosewheel leg which is retractable about the axis 11 below the aircraft floor 14 comprises telescoping portions 13 and 15, the upper member 15 having an inner, rotary sleeve 17 which transmits steering motion to the nosewheels. The steering mechanism is housed within a casing 19 and comprises a cylinder 22 normally prevented from rotation by a splined connection 55 with a clutch member 52 upwardly urged by the pressure of fluid in a line 51 against the force of springs 53 whereby dog teeth 54 in the clutch member and on a stationary part of the housing interengage. A piston 25 operates within the cylinder 22 and comprises a spool valve 27 and fluid supply and return passages. The valve spool 27 is moved axially for actuation by rotary movement of levers 35 through a rod 33 which has a splined connection with a quill 32 which has a multistart threaded connection 38 with a stationary sleeve member 37, backlash in both directions being prevented by a spring 39. Movement of the spool 27 in either direction causes a flow of fluid to either space 29 or 28 whereby movement of the piston 25 is caused until a new position of neutrality is reached. The piston 25 has a skirt 44 in sliding contact with the casing 19, and a number of radial pins 47 extend between the skirt and the piston, each carrying a pair of rollers 48 which lie in helical slots in the cylinder 22 and a sleeve 45 which is keyed to the outer member 15 of the leg. The helical slots are of the opposite hand in the members 22 and 45, respectively, whereby, when the piston is moved axially it is caused to rotate and the sleeve member 45 is caused to rotate simultaneously at a faster rate. When the power fluid supply is cut off, pressure in the line 51 drops, whereby the dog teeth 54 are disengaged and the nosewheel is allowed to castor. Means may be provided for preventing rotation of the piston 22 whereby the rotary movement of sleeve 45 will be diminished. The helix angles may progressively change to give varying steering characteristics. Pressure relief valves 30, 31 connecting to reservoir are provided which prevent build up of excessive torque, e.g. should the nosewheel strike a runway kerb.