Patent GB-584260-A (GB)
Title: A new or improved combined hydraulic and pneumatic system for conserving and transmitting power
IPC: F41A25/20
Filed: 1943-11-30
Abstract: 584,260. Shock - absorbers. BIRMINGHAM SMALL ARMS CO., Ltd., PERRY, C. A., and WACKROW, R. D. Nov. 30, 1943, No. 19968. [Class 108 (iii)] [Also in Group XXI] A fluid-pressure system comprises a piston and cylinder adapted to be connected respectively to two relatively-movable parts of a mechanism, a chamber 13 connected with the cylinder by a passageway to receive liquid displaced from the cylinder, and a diaphragm 21 and a flexible, gas-containing receptacle 17 housed in the chamber, the diaphragm being maintained in contact with the receptacle which it isolates from the liquid and compresses when it is displaced in the chamber by liquid received therein from the cylinder. The invention is shown applied to a firearm comprising a barrel portion 1 containing a chamber 3 into which ammunition may be introduced automatically and fired by a firing pin 5 mounted on a breech block 7 secured to a breech body 9. The chamber 13 formed in a casing 11 secured to the body 9, is closed by a detachable cover 15 and houses the elastic receptacle 17, e.g., of rubber, beneath which is the metal diaphragm 21 having a tubular stem 23 passing through a tube 25 in the receptacle 17 and into a stem 27 on the cover plate to provide a guide for the diaphragm. The receptacle is filled with gas, e.g., nitrogen, through a valve 29. The chamber 13 communicates through passages 37 with the interiors of two hollow piston-rods 35 secured on each side of the casing 11, each rod having at its forward end a piston-head housing a valve 41 which is normally spring-pressed on its seating 39. The rods are contained in cylinders 45 secured to and movable with the breech body. 9 and engaging guideways 47 on the barrel portion, and the cylinders communicate with the passages 37 through slots 57 in the rods. In operation, on cocking the firearm, oil in the cylinders 45 is forced into the chamber 13 moving the diaphragm 21 to compress gas in the receptacle 17 and on release of the breech mechanism, the gas expands and, through the diaphragm, forces oil through the passages 37 into the piston-rods 35, to unseat the valves 41 and project the cylinders and breech mechanism rapidly forwards until the firing pin 5 strikes the percussion cap of the round of ammunition in the chamber 3. To prevent damage if there is no charge in the chamber 3 lugs are provided on the barrel to ,engage buffers 49 on the cylinder heads. When the firing pin 5 reaches the percussion cap, the piston-heads on the rods 35 lie adjacent internally-extending flanges 55 on the cylinders so that, on recoil, rearward flow of oil to the chamber 13 is initially restricted and unduly rapid rearward movement of the breech mechanism is checked, the oil pressure maintaining the valves 41 on their seatings. The front ends of the cylinders are internally tapered and. comrriunication between these parts and chambers 48 for the buffers 49 is maintained by a groove on each buffer stem 51 so that as the breech mechanism reaches its most forward position, oil in the forward parts of the cylinders acts as a resilient shock-absorbing means. As a result of the rearward movement, the gas in the receptacle 17 is again compressed and when the movement is checked the gas expands and causes the breech mechanism to be moved forwards again automatically. The invention may be applied other than to firearms, e.g., to motor vehicle suspensions.