Patent GB-483994-A (GB)
Title: Improvements in or relating to the operation of mechanical devices by means of gas-generating cartridges and charges
IPC: F42B3/04
Filed: 1936-10-22
Abstract: 483,994. Gas-producing cartridges for mechanical operations. HOLM, J. M., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. Oct. 22, 1936, No. 28785. [Classes 9 (i) and 9 (ii)] Relates to gas-producing cartridges for the operation of mechanical devices in which a movable part is brought into contact or engagement with a second movable part, having a relatively greater inertia or subjected to greater resistance, to initiate and maintain the motion of the latter part for a necessary time at a desirably high speed. According to the invention, the cartridge comprises a substantially ashless self-combustible charge and initiating means therefor, the said charge comprising at least two sections of which the first is directly ignitable by the initiating means and is compacted and adapted for the slow generation of gas over a period at least of the order of one second, while the second is adapted for the rapid generation of gas and is so separated from the igniting means that its ignition is prevented until substantially complete combustion of the first section has occurred. A partition is used for preventing premature ignition of the second charge section. This partition may be constituted by a compacted portion of the first charge section. Or, the partition may be a disc of celluloid, cardboard, fibre, felt, ebonite, or phenol formaldehyde resin. In one form of cartridge, Fig. 3, the igniting means comprise a percussion cap 3 followed by a priming charge 4, the first section of the charge comprises four elements 5, 6, 11, 13, and the second section of the charge consists of rods 7. The cartridge is closed by a card - board disc 9 secured by a turnover 10. The gases produced are discharged by a lateral vent hole 2 near the base of the cartridge. Similar cartridges are described with a smaller number of elements for the first section of the charge. In a modification, the first section of the charge is placed in front instead of behind the second section and is ignited at the front by a priming charge fired by a quickmatch extending from the percussion cap through a central tube ; the gases are discharged through the front end of the cartridge. In another form of cartridge ignited at the front, Fig. 4, the priming charge 4 is ignited by an electric fuze head 17 connected by leads 18 to the metal base 14 and an insulated electrode 15 therein, the leads 18 passing alongside the charge. The priming charge is covered by a celluloid disc 19 secured by the turnover 10. A friction match or an electric spark may also be used for ignition. The following compositions are mentioned as suitable. For the percussion cap : a mixture of mercury fulminate 6 parts, antimony sulphide 4 parts, and potassium chlorate 6 parts ; a mixture of lead styphnate 26 parts, barium nitrate 45 parts, antimony sulphide 7 parts, calcium silicide 14 parts, and tetrazone 4 parts ; and a mixture of mercury fulminate 19 parts, antimony sulphide 43 parts, potassium chlorate 2 parts, mealed black powder 2À4 parts, and sulphur 2À4 parts. For the priming charge, black powder, dry fibrous nitrocellulose, sporting powder, and schultze smokeless powder. For the first section of the charge which may be a single charge element or a composite charge as described in Specifications 454,091 and 477,956: colloided nitrocellulose ; celluloid ; Ardeer cordite (a mixture of nitroglycerine, nitrocellulose and diethyldiphenyl urea) ; a mixture of guanidine nitrate, ammonium dichromate, and nitrocellulose ; mixtures of nitro guanidine, and guanidine nitrate, with and without nitrocellulose. For the second section of the charge, a smokeless propellent for example Ardeer cordite. The Provisional Specification describes also an apparatus, Fig. 6, showing the use of the cartridges. A cartridge 23 is placed in a firing-chamber 24 closed by a breech block 25. The gases from the cartridge pass through a pipe 27 to a cylinder 28 where they drive a piston 29 to the right. The motion of the piston is free until a rack 34 on the piston rod 33 strikes a pinion 35 and rotates a fiy-wheel 36 braked by a belt 37 anchored at one end 39 and loaded with a weight 38 at the other end. The motion of the piston rod is guided by roller bearings 40, 41. A " free-wheel " connection allows free counterclockwise rotation to the pinion 35 relatively to the fly-wheel.