Patent GB-609883-A (GB)
Title: Feeding ammunition to automatic cannon, machine guns and the like
IPC: F41A9/03
Filed: 1946-05-23
Abstract: 609,883. Cartridge feed mechanism. MARTIN, J., and MARTIN-BAKER AIRCRAFT CO., Ltd. May 23, 1946, No. 9004. [Class 92 (ii)] Relates to mechanism for feeding ammunition from cartridge belts, formed of a series of links, to machine guns and the like, the mechanism being so arranged that the belt is fed stepby-step into position for separating each round from the belt to load it into the gun as required. According to the invention the belt is fed in unison with the firing movements of the gun and transversely to the axis of the gun by two rotatable scroll members one engaging the front part and the other the rear part of each cartridge to separate each round from the belt and to place each round in the correct position for loading into the gun. The invention is described as applied to a 20 mm. Hispano gun. The mechanism has a casing 1 adapted to be mounted on the magazine carrier of the gun between a fixed abutment 10 and a magazine catch lever 12. The casing 1 is divided into two parts 2 and 3, by a longitudinal dividing wall 4, the part 2 accommodating- the feed scrolls and the part 3 the actuating mechanism. An intake opening 5, Fig. 4, adjusts the cartridge belt to the feed mechanism and the links are ejected to a shoot through an opening 6. Two scrolls 14 and 15 are arranged transversely across the casing 1, with extension shafts 16 and 17 respectively, passing through bearings in the dividing wall 4. The shaft 17 has a squared end for hand operation to initiate the feed of the belt. Toothed gears 20 and 21, respectively, on the shafts 16 and 17 are connected in driving engagement by idler gears 22. Gearing with a pinion 27 on the shaft 17 is a toothed rack 30 of hollow cylindrical form and mounted to slide in guides 31, 32 fixed in the casing 1, the guide 32 being slotted for passage of the rack teeth, during reciprocation of the rack by the recoil movement of the gun. Mounted on the gun body is a bracket 40 carrying a pivotally mounted spring-pressed pawl 41 engaging with a member 43 on the boss 44 of a lever 45 connected by a link 49 to operate the rack 30. The lever 45 is pivoted at 46 to a bracket 47 on the casing 1 which is maintained stationary. The end 42 of the pawl 41 disengages from the member 43 after a predetermined movement of the rack lever 45, to avoid damage to the feed mechanism by excessive recoil movement. A buffer spring 34 returns the rack after each recoil movement of the gun and during this return movement the rack acting through a one-way driving ratchet 28 imparts a step-by-step movement to the scrolls 14 and 15. A link ejector platform 9 is spring-pressed towards the intake opening 5 over a feed mouth 7 communicating with the gun breech. The foremost incoming cartridge fed in by the scrolls 14, 15 presses against upstanding tabs 66 on the platform 9 forcing the platform back while cam portions of the crolls 14, 15 force the cartridge into the feed mouth 7 out of its link, the disconnected link passing between the tabs 66 to the discharge opening 6. When the feed mouth 7 holds two cartridges a pin 73 on a stop lever 70 engages with the platform 9 to bring the upper end of the lever 70 into the path of a scroll stop 76 and so prevent further feeding until the lower cartridge in the feed mouth 7 is removed from the lips 8 by the breech block. The last round is held by flat blade springs in the feed mouth 7, Fig. 3 shows one spring 80. A guide 83 in the feed mouth 7 aligns each shell. The Provisional Specification describes a modification of the connection between the gun body and the rack and the drive from the rack to the scrolls. It also describes a guide for the cartridge belt.