GB689114A - Improvements in or relating to retractable undercarriage for aircraft - Google Patents

Abstract

689,114. Aircraft undercarriages. BRITISH MESSIER. Ltd. June 8, 1951. [Aug. 14, 1950] No. 20160/50. Class 4. [Also in Group XXIX] An aircraft undercarriage comprises a frame member having a pivotal mounting for attachment to an aircraft body for retraction purposes, a retraction jack for raising and lowering the frame member, a wheel carrying unit steerably mounted with respect to the frame member, a steering jack having means for attachment at one end to the aircraft body and at the other end to a steering arm on the wheel carrying unit, and means to lock the steering jack so that it can act a a strut during retraction in order to rotate the wheel-carrying unit about its longitudinal axis. The undercarriage comprises a frame casting 11 which is pivotally mounted on the aircraft at 12 and secured in the extended position shown by a projector 35 which engages a latching device actuated by a fluid pressure jack Fig. 5, (not shown). The body 16 of an oleo-pneumatic shock absorber is journaled in the frame 11 and the ram 19 carries a pivot 21 on which is journaled an arm 20. A wheel 23 is pivotally attached at 22 to the arm 20, the other end of which is connected by a link 24 to a lug 18 projecting from the body 16. An arm 25, fast with the upper portion of the body 16, is pivotally connected at 26 to the piston rod of a double acting steering jack 28 (see Group XXIX) secured to the aircraft structure by a universal mounting 27 and a retraction jack 31 connects the frame 11 to the aircraft structure. The jack 28 is so constructed that when it .is not biased for steering purposes it acts as a strut to centralise the undercarriage in a fore and aft plane and the relationship between the points of attachment to the aircraft structure of the frame 11 and the jacks 31 and 28 is so arranged that during retraction of the undercarriage the body 16 and the parts carried thereby are rotated with respect to the frame 11 so that the wheel is stowed in the substantially horizontal position shown by chain dotted lines, the axis of the pivot 12 being inclined to a fore and aft plane by an amount that ensures that the centre of the stowed wheel lies in the central longitudinal plane of the fuselage. The supply of liquid may be cut off from the connection 52 in order that the jack may permit limited castoring movement of the undercarriage to take place and a suitable restriction may be introduced into the hydraulic connections to damp such movement.