Patent GB-236799-A (GB)
Title: Improvements in or relating to automatic machine guns
IPC: F41A19/05
Filed: 1924-11-11
Abstract: 236,799. Browning, J. M. July 14, 1924, [Convention date]. Fire between aircraft propeller blades, controlling and synchronizing.-A trigger mechanism unit, carried by the breech casing of an automatic gun, has means whereby the gun can be fired at will either in synchronism with a rapidly rotating member or automatically at its normal rate. As shown, the complete mechanism for controlling the firing comprises an impulse generating and transmitting unit, a trigger mechanism unit and a breech-block unit. The impulse generating and transmitting unit comprises a rotating cam 3<a>, Fig. 1, the angular position of which on its shaft is adjustable. two sliding rods 7, 8 supported and guided by tubes 11, 12, and a bell-crank lever 9 between the two rods. The rear end of the tube 12 is detachably connected to the trigger mechanism unit. The trigger mechanism comprises a cranked trigger 6, Fig. 9, acted upon by the impulse-sending rod 8, and a cranked hand trigger 29, Fig. 13. Both these triggers are mounted on the same pivot pin 6b and their horizontal arms engage a transversely pivoted lever 25, Fig. 10, extending into the breech casing and adapted to actuate a searreleasing lever 34. A lever 27, Fig. 9, operated by a cable 28 is provided for putting the synchronized trigger out of action. The two triggers and the lever 27 are mounted on a frame-part 24 which is movably mounted in a slot in a frame-part 23 bolted to the side-plate 21 of the breech casing, the frame-part 24 being thereby capable of a limited longitudinal movement relatively to the casing so that it may remain immovable relatively to the impulse sender when the gun casing recoils. The transverse lever 25 has a downwardly extending offset portion 25f engaged by the arm 6<d> of the synchronized trigger, and is mounted on a pivot 25<a> on the fixed frame 23 in such a manner that it is capable of a lateral sliding movement, being normally pressed inwards by a spring. When the breechblock recoils, a cam thereon moves the lever 25 outwards and disengages the offset portion 25f from the trigger arm 6<d>, thereby breaking the operative connection between these parts. The lever 27, for rendering the synchronized trigger inoperative, has a shoulder 27<c> adapted, when the lever is turned by its spring 27<b>, to engage under the arm 6<d> of the trigger and hold it in the raised position. In this position the trigger arm engages the side of the offset portion 25<f> of the lever 25 which is thereby retained in its outward position but is capable of being operated by the hand trigger. A light spring draws the end of the rod 7 out of engagement with the rotating cam when the synchronized trigger is rendered inoperative. The. firing mechanism carried by the breech-block comprises a sliding firing pin 30, Fig. 11, and a vertically-sliding sear 33 having a bevelled projection 33<a> engaging a bevelled shoulder 30<b> on the firing pin. The sear is held raised by a detent 34 and, when this is released by the lever 25, is cammed down by the inclined shoulder. Specifications 133,329, 133,351, and 133,352 are referred to.