GB713626A - Improvements in steering means for aircraft landing gear - Google Patents

Abstract

713,626. Steerable undercarriage for aircraft. ELECTRO-HYDRAULICS, Ltd. May 9, 1950 [Feb. 11, 1949], No. 33123/52. Divided out of 711,832. Class 4 A servo steering system for the steering of aircraft upon the ground through its landing gear comprises a steerable castor unit, including two wheels spaced one on either side of the pivot axis of the castor, steering of the aircraft being effected during forward motion of the aircraft, by disturbing the balance of natural rotation of said wheels, which is attained by mechanical means adapted to transfer energy from one of the wheels to the other, so that the forward motion of the aircraft is utilized to swivel said unit into a new position of balance, dependent upon the extent of the disturbance. The wheels 4, 5 are mounted for free rotation on a common axle 30 supported by an axle casing 8 mounted for castoring movement, the wheel 4 being provided with an internal gear ring 34 and the wheel 5 with an external gear ring 33, these rings meshing with pinions 40, 42 connected by half axles 39, 41 to gears 35, 36 of a differential mechanism of which the other pair of gears 37, 38 are mounted in a cage 47 rotatably mounted within a box 59 fast with the casing 8. Back plates 48, 49 are freely mounted in the half axles. 39, 41 and as shown in Fig. 1A they are geared to the cage 47 by planet gears 91, 94. Clutch plates 45, 43 normally urged from the back plates by springs (not shown) are also mounted on the half axles and a fluid pressure motor 50 and levers 55, 56 are provided whereby one wheel may be braked selectively, whereupon the other wheel will be accelerated through the epicyclic and differential mechanism and cause the undercarriage to castor for steering. In alternative embodiments the braking mechanism may be dispensed with and differential operation of the gear mechanism effected by a reversible electric or fluid operated motor operating through reduction gearing on the cage 47. The motor may be used to pre-rotate the wheels before landing. Specification 539,405 is referred to.