GB611827A - Improvements in or relating to shock-absorbers - Google Patents

Abstract

611,827. Aircraft landing gear. SOC. D'INVENTIONS AERONAUTIQUES ET MECANIQUES, S.I.A.M. May 9, 1946, No. 14099. Convention date, July 31, 1941. [Class 4] [Also in Group XXXII] In an oleo-pneumatic shook-absorber of the kind in which liquid contained between two pistons 2, 12 which are united to move as one passes through small passages 15 in a diaphragm 9 between them, and in which the outer face of one of the pistons 12 is subjected to a gas 13 under pressure, the pistons 2, 12 are connected by a traction rod 11 carried by one of the pistons 12 and slidable relative to the other 2, and are provided with means to limit the maximum separation between the pistons and with means to permit escape of the liquid. The pistons are slidable in a cylinder 1 and their separation is limited by an abutment 14 on the rod 11. Flow through the passage 15 is controlled by valves 16 and the liquid space above the diaphragm 9 is connected by a port 23 with a valve chamber 25 which is divided by a valve and seating 32, 26 into two chambers 27, 28. A floating piston 29 in the chamber 28 is acted on by a calibrated spring 30. The chamber 28 on each side of the floating piston 29 is connected respectively by pipes 40, 36 to each cylinder of a double acting pump 42, the pistons 44, 45 of which are actuated by a lever 49. The pipes 40, 36, which embody inlet valves 51, 52 and outlet valves 53, 54 are connected by a valve 60 operable by a catch 61 on the lever 49. The pipe 40 is also connected to a hydraulic accumulator 41 while the pipe 36 is also connected to an annular liquid space 38 between a hollow rod 3 of the piston 2 and the cylinder 1. In a modification, Fig. 2 (not shown) the piston rod 3 is subdivided by a concentric inner tube into an outer annular chamber which forms the accumulator 41 and a concentric inner chamber which houses the valve chamber 25. Operation.-In the extended position (shown) of the shock absorber, suspension loads on the piston rod 3 are borne by compressed gas in the space 13 above the piston 12 since there is no escape for liquid in the space 8 between the pistons 2, 12. The shock absorber is retracted by pumping with the lever 49 pressure produced thereby being transmitted by the pipe 36 to the floating piston 29, which engages the stem 33 of the valve 32, which opens and permits liquid to escape from the space 8. Liquid from the space 8 is forced into the accumulator 41. Extension is effected by opening the valve. 60 to equalise pressure in the spaces 8, 38.