Patent GB-518130-A (GB)
Title: Improvements in or relating to collapsible struts for retractable under-carriages foraeroplanes and other purposes
IPC: B64C25/14
Filed: 1938-08-15
Abstract: 518,130. Remotely-controlled fastenings; stays for hinged articles. CAREY, F. H. Aug. 15, 1938, No. 24070. [Classes 44 and 65 (i)] [Also in Group XXXIII] A collapsable strut for the undercarriages of aeroplanes &c. comprises two limbs pivoted together, one limb extending beyond the pivot and the other having a lateral projection short of the pivot, in combination with a pair of laterally disposed links hinged together at one end and pivoted at their other ends to the extension and lateral projection respectively, a hydraulic jack being connected to one of the links or to the point of articulation of the two links. Means for locking the strut in extended position are provided. The strut may be used as a stay for a hinged wheel-carrying member or it may itself constitute the wheel-carrying member, and means are provided for locking the said member in its raised position.Fig. 3 shows a laterally movable wheel-carrying member 2 which is raised and lowered by a collapsable strut comprising two parts 3, 4 pivoted together at 5, the part 4 having a lateral projection 6a. Two links connected at one end by a pivot 11 are connected at their other ends to pivots 12, 13 respectively on the projection 6a and an extension of the member 3. A hydraulic jack 10 is connected between the pivot 11 and a member 21 pivoted to the aircraft and rigid with the member 3. Contraction of the jack moves the parts to the position shown in chain line whereupon a pin 14 on the member 2 is engaged by a locking device 15. The application to a longitudinally folding undercarriage and to a tailwheel also is described. Figs. 5, 6 and 7 show diagrammatically the connections between the jack 10, the locking device 15 and a lock for securing the members 3, 4 in their extended position. A hook 24, Fig. 5, normally held in its operative position by a spring 30 acting on a piston 26 is released by admitting oil under pressure to the left of the piston. As the piston reaches the end of its stroke its rod 25 unseats a ball valve 28 to admit pressure fluid to the jack 10 in a direction to extend the undercarriage. A similar apparatus, Fig. 6, is used to lock the parts 3, 4 in extended position the spring 30 maintaining laterally-placed latches 35 in engagement with co-operating fixed catches on the opposite member. When pressure fluid is introduced through a pipe 36 the latches 35 are first released and then the valve 28 is unseated to admit fluid to the jack 10 to collapse the strut. A spring pressed packing 27 prevents pressure from building up prematurely in the chamber 35<1> due to movement of the piston rod or to leakage past the ball 28. Alternatively a latch similar to that shown in Fig. 5 may be used to lock the strut, or the piston rod may be extended to form an axial bolt which enters the hole in the other member, or the piston rod may actuate toggle links to withdraw two transverse bolts engaging forked parts of the other member of the strut. Fig. 16 shows a wheel-carrying member 2 formed in two parts collapsable by a jack 10, a strut 40 being hinged to a point on the lower part of the member 2. The strut 40 also may be collapsable by means of a second jack and the strut locks arranged to open in sequence before the jacks begin to move. Alternatively a collapsable strut may be so lined to a folding wheel-carrying member that the latter is folded simultaneously with the strut when the jack associated with the latter is actuated.