GB574705A — Improvements in and relating to machine guns

USPTO Abstract

574,705. Automatic guns. BOULTON PAUL AIRCRAFT, Ltd., FREEMAN, J: O., and COX, J. H. April 26, 1940, No. 7496. [Class 92 (ii)] Apparatus for controlling the number of rounds fired by a machine gun when the firing button is pressed, comprises electromagnetic or electrodynamic control means, the energizing circuit for which includes a normally open firing switch closed by the button and a normally closed control switch opened by a control member when this has moved forward a predetermined number of steps, corresponding to rounds fired, by mechanism operated by the recoil of the gun. The arrangement includes solenoid or oscillating electric motor means for stepping the control member and counting the rounds and similar electric means for resetting the parts. The electric circuit shown in Fig. 6 includes a firing switch 63, a switch 6, 7 operated by the setting knob, a changeover switch 27, 65, 64 for opening and closing the circuit through the coil 58 of the firing solenoid, a resetting solenoid coil 46 and counter solenoid coil 36, and a switch 75 closed by the recoil mechanism. Figs. 1 and 2 show one form of the control apparatus. A knob 3 is pressed to close the switch 6, 7 and rotated to set through a wheel 14 a stop 16'which controls the position occupied by a ratchet control arm 17 under the action of its return spring 19. As firing proceeds, the counter solenoid 36, energized by the recoil-operated switch 75, moves an arm 32 carrying a pawl 22 to feed the arm 17 one tooth at a time under the control of a retaining-pawl 37. When the desired number of rounds have been fired, a pin 24 on the arm 17 engages a sector-arm 23 to operate the change-over switch 27, 65, 64, thus opening the firing circuit, and closing the circuit through the resetting solenoid 46. This actuates, through a rod 44 and bell-crank lever 41, a slotted member 39 which operates on the pins 50, 51 to release the feed and retaining pawls and allow the arm 17 to return to the stop 16. The arm 32 may operate a known form of counter mechanism 79. The solenoids 36, 46 may be replaced by oscillating electric motors of known type. Fig. 3 shows the means operated by a solenoid 58 for actuating the sear 57 to release the gun breech block 55 from its rear or cocked position. The armature of the solenoid 58 operates a valve 59, admitting pressure air to a piston 60, the rod of which has a cam 61 for moving a follower 62 on a rod engaging the sear. The recoil-operated switch 75, Fig. 4, mounted on a spring-pressed pivoted arm 69, is forced between contact blades 66, 67 by the passage of the breech block over a roller 71 on the arm.