Patent GB-513179-A (GB)
Title: Improvements in or relating to breech mechanism for cartridgeoperated engine starters or other cartridge-operated apparatus
IPC: F02N13/00
Filed: 1938-04-14
Abstract: 513,179. Generating combustion products under pressure. COSTA, H. DA, and PLESSEY CO., Ltd. April 14, 1938, No. 11530. [Class 51 (i)] [Also in-Groups XXVII and XXI] In a breech mechanism for cartridge-operated engine starters or other apparatus, in which a rotary magazine 17 has cartridge tubes 18 brought successively into communication with an opening in a combustion chamber 10, a sealing ring 19 is movable in the combustion chamber by the pressure of the gases generated by the firing of a cartridge to seat on the delivery end of each of the cartridge tubes. As shown the combustion chamber 10 has a boss 12 for connection to the engine starter, and the magazine 17 rotates on a rod 15 connecting a breech member 16 to a flange 13 on the combustion chamber. The sealing ring 19 is a tubular piston carrying piston rings 20 and coned at 21 to engage the coned end of each of the cartridge tubes 18. The piston is initially applied to the end of a cartridge tube by the pressure of a spring 33 acting through levers 28, 29 connected by a link 30 and pivoted on a spindle 31 having a boss 32 sliding on the rod 15 and engaged by the spring 33. Rollers 38, 39 on the levers 28, 29 engage grooves 40, 41 in a cam 42 rotatable to-and-fro by means of an arm 81 to move the piston out of and into engagement with a cartridge tube. The to-andfro movement of the cam 42 also effects the rotation of the magazine one step to bring the next cartridge tube into position, by means of a draw pawl 60 and a thrust pawl 61 acting on studs 62. Violent movement of the cam 42 is prevented by a hydraulic damping device 71. The cartridges are fired by an electric contact pin 46 connected to a lever 48 engaging a groove 49 in a rod 50 adjustably connected to a socket 51 on the piston 19, so that movement of the piston away from the cartridge tube also retracts the firing pin. Firing takes place when the piston 19 properly engages the cartridge tube, breaking contact between members 55, 56 which otherwise short-circuit the firing pin. The cam 42 may be actuated automatically in conjunction with the firing of the cartridge by means shown in Figs. 7, 9 and 10. The arm 81 on the cam is pivoted to a connecting rod 82 rotatable on a stud 83 on a crank disc 84 driven by an electric motor 86 through a pinion 85. A cam surface 87 on the connecting rod cooperates with a stud 88 on a lever 89 pivoted at 90 and pivotally connected at 94 to an armature 92 for an electromagnet 93. A tension spring 95 normally retracts the armature and moves the stud 88 into the path of the cam surface 87. The armature passes through an opening in a spring blade 96 controlling electric contacts 98 ... 100 and has a notch 97 for locking the spring blade. The contacts 98 ... 100 are connected as shown in Fig. 10 to the electromagnet 93, the motor 86 and the firing pin 46, and through a push-button switch 103 to a battery 104. On closing the switch 103, the electromagnet 93 is energized but the armature is held by the blade 96 ; the motor 86 drives the disc 84, moving the cam surface 87 away from the stud 88 and allowing the spring 95 to turn the lever 89 into engagement with a stop 105, whereupon the notch 97 is opposite the blade 96 and the armature is attracted to the magnet. The continued rotation of the disc 84 effects the to-and-fro movement of the cam 42 to retract the piston and firing pin, to bring the next cartridge tube into position, and to re-position the piston and firing pin. The cam surface 87 again engages the stud 88, rocking the lever 89, and the initial movement of the armature 92 moves the blade 96 to engage contacts 98, 99 completing the firing circuit. Further movement of the lever 89 separates contacts 99, 100 and so breaks the circuit of the motor 86. When the switch 103 is released, the armature 92 releases the blade 96 and the parts are in their original positions. Reloading of the magazine with cartridges may be effected on moving aside a shutter 107, Fig. 1. To enable this to be done when the mechanism shown in Figs. 7-10 is employed, a rotatable handle 108, Fig. 8, is secured to a formed arm 109 engaging a stud 110 forming an extension of the crank pivot 83. The handle108 is rotated through part of a revolution to rotate the cam 42 sufficiently to allow the magazine to be turned free of the piston 19 and the firing pin. To prevent turning of the motor 86 by this means, a lost-motion connection is provided between the pinion 85 and a warm wheel 112 driven by a worm 111 on the motor shaft, or the pinion 85 may be driven through a ratchet and pawl. The Provisional Specification describes a construction in which a longitudinally movable slide moves the piston initially into engagement with a cartridge tube, and co-operates with abutments on the magazine to effect the rotation of the magazine.