GB530373A - Improvements in or relating to mechanism for producing angular movement for use in retractable under-carriages for aircraft - Google Patents

Abstract

530,373. Retractable undercarriages for aircraft. AUTOMOTIVE PRODUCTS CO., Ltd., and SIMPSON, J. K. May 6, 1939, Nos. 13612 and 14636. [Class 4] [Also in Groups XXIX and XXXI] A retractable mounting for a wheel on an aircraft comprises a tubular strut adapted to move angularly about a substantially horizontal pivot shaft in the aircraft wherein is coupled to a crank on the pivot shaft, the piston being moved axially within the tubular strut to move the latter bodily about its pivot. In one form a retractable leg for an aircraft undercarriage comprises a tubular member 34 secured in a sleeve 12 pivoted about a fixed transverse trunnion 18. The trunnion, which is a fluidtight fit in the sleeve 12, is divided and the two parts are connected together by pins 23, 24 on a diameter which is at an angle to the axis of the tube in its normal position. The lower part of the tube forms the shock absorber which is separated from the upper part by a partition 17. A piston 33 in the upper part is connected by a rod 31 to the pin 23, and an extension 35 of the piston works within a second piston 36 having an extension 37. A spring 41 between the pistons normally urges the extension 37 into engagement with a fixed notch 57. Upon admitting fluid through a port 49 in the trunnion to the space above the piston 36, the extension 37 is first withdrawn from the notch and then the two pistons move together and turn the leg into the position shown in chain lines in Fig. 2, to retract the undercarriage. By admitting fluid through a port 56 in the opposite end of the trunnion into the space between the piston 33 and the partition 17 the leg is again extended. By admitting fluid also to the annular space around the shock absorber plunger the leg may be shortened. In a modification a single piston having an extension for actuating locking pawls has a lost motion connection to the connecting rod. Upon admitting pressure fluid the first movement of the piston effects unlocking of the leg in either of its two positions. In another modification the upper part of the tube is closed and a piston connected to one of the crank pins by a link works in the upper end of the shock absorbing cylinder. Movement of the piston to raise the leg consequently compresses the resilient shock absorber and energy is stored for re-entering the leg. The last two modifications may be combined so that the fluid acts on both pistons during retraction of the leg. The leg may form part of a permanent jacking device on a motor car so that the jack when not in use occupies a horizontal position and automatically moves into a vertical position when pressure fluid is admitted. Sealing rings as described in Specification 474,055, [Group XXVI], may be used to render the working parts fluid tight.