GB496200A - Improvements in and relating to machine guns - Google Patents

Abstract

496,200. Hydraulic apparatus. NASH, A. G. FRAZER-. May 9, 1938, No. 24520. Divided out of 493,468. [Class 69 (ii)] [Also in Group XXI] Relates to a double-acting triggeroperating device 3 for machine guns, in which fluid pressure acts positively on a piston 2 in one direction to fire the gun and in the other direction to interrupt fire. According to the invention, the area on the piston exposed to pressure during the firing stroke is less than the area exposed to the pressure acting to interrupt the fire, and part of the smaller area is obturated in the position shown, as for example by a stepped portion 26 of the piston, so that the pressure to cause firing first acts on a small annulus 27 and later on a larger annulus. This construction ensures that leakage round the piston 2 will not cause unintentional firing since there is always excess pressure tending to keep the piston in the non-firing position, and, further, when the firing stroke starts, there is a sudden increase in the force acting on the piston annulus. In the apparatus shown, the piston is controlled by a slidevalve 23 actuated by a remote trigger x. The valve is shown in the non-firing position in which the pressure feed pipe 15 is connected to a pipe 9 leading to a port 5 in the cylinder 3, the port 4 being then connected by a pipe 8 to the exhaust pipe 16. When the valve 23 is moved to the right to cause firing the pressure fluid enters at the port 4 and exhaust takes place through the port 5.