Patent GB-438998-A (GB)
Title: Improvements in landing gears for aeroplanes and other shock-absorbers
IPC: B64C25/60
Filed: 1934-12-20
Abstract: 438,998. Shock-absorbers. MERCIER, J., 131, Boulevard de la Seine, Neuilly-sur- Seine, France. Dec. 20, 1934, No. 36517. Convention date, Jan. 9. [Class 108 (iii)] In a shock-absorber particularly for aeroplane landing-gears, motor-vehicle suspensions, locomotive buffers, &c. of the type in which a deformable chamber is adapted to communicate with an auxiliary chamber or chambers through one or more passages which are closed by obturating members when the opposite walls of the deformable chamber have been moved a certain distance from their initial relative positions, at least two passages closed by obturating members are provided between the deformable and auxiliary chambers, one of the passages being opened as soon as the opposite walls of the deformable chamber begin their return movement, and the other passage being opened as soon as the pressure in one of the chambers exceeds a predetermined value. In the construction shown in Fig. 1, the deformable chamber 1 is formed in a cylinder between a slidable piston 6 and a fixed partition 3 and communicates with the auxiliary chamber 2 through a tube 7 fixed to the piston. The tube slides easily in a second tubular member 5 which fits tightly in a hole 4 in the partition. In operation, on contraction of the chamber 1 fluid is expelled through orifices 9, 10 in the tube 7 into the chamber 2 until the piston abuts the end of the tube 5 when the orifice 9 is closed and the fluid in the chamber 1 is compressed, thus offering increased resistance. During this compression the tube 5 is forced into the chamber 2. Excessive pressure is prevented by a safety valve 11. On the return movement the orifice 9 is uncovered and places the chambers 1, 2 in communication again thus preventing abrupt expansion of the chamber 1. The operation of the device is similar when the chamber 1 is expanded initially, a vacuum of increasing value being formed in the chamber when the orifice 10 is closed by the tube 5. In a modification the tube 5 engages a hole in a sliding piston and the apertured tube 7 extends through the tube 5 and at its ends abuts or is separated slightly from the end walls of an enclosing cylinder. In another construction, Fig. 2<a>, a tube 18<a> fits tightly around the piston 14 and is separated from the enclosing cylinder 13 so that, in operation, fluid passes between the tube and cylinder until the tube engages an end of the cylinder when the resistance is increased by compression of the fluid in the space between the piston, the tube and the end of the cylinder. Fig. 3 shows a further construction in which chambers 27, 28, 29 are formed by telescoping, closed cylindrical members 23, 24, the auxiliary chambers 27, 29 being in permanent communication through a tube 26 and orifice 31 and also communicating with the deformable chamber 28 through a tube 30 tightly fitting a hole in the piston 25. In a further construction, Fig. 4, an orifice 36 in an auxiliary chamber 34 is adapted, during operation, to be closed by an auxiliary spring-pressed piston 41 carried by the main piston 37, the piston 41 being slidable in a tube 38 fixed to the main piston. On compression of the device, the orifice 36 is closed by the piston 41 after a predetermined travel and the fluid in the chamber 33 is then compressed, raising the valve 42 and entering the tube 38 above the piston-end 39. During the return movement this compressed fluid is trapped by the valve 42 closing and the auxiliary piston consequently moves with the main piston, thus uncovering the orifice 36. The trapped fluid gradually leaks back into the chamber 33. Fig. 5 shows another construction in which on upward movement of the piston 57 fluid is forced into an auxiliary chamber 46 through a passage 48 in a partition 47. The pressure in chamber 45 rises more rapidly than that in chamber 46 and when the pressure difference reaches a certain value a valve 51 is lifted and fluid passes along a conduit 55 and raises a spring-pressed slide-valve 49 which obstructs the passage 48. On the return movement the valves 51, 49 are spring-pressed to their original positions. In a modification the partition 47 separates slidable pistons connected by a hollow rod.