Patent GB-459605-A (GB)
Title: Improvements in or relating to machine guns
IPC: F41A7/04
Filed: 1935-08-29
Abstract: 459,605. Machine guns. VICKERSARMSTRONGS, Ltd., and LARSSON, C. A., Vickers House, Broadway, Westminster. Aug. 29, 1935, No. 24176. [Class 92 (ii)] In a machine gun of the kind having a reciprocating lock and a trip-piece movable into and out of the path of the trigger, means are provided which operate to retain the trip-piece in the path of the trigger until after the lock has been held in its rearward position, so as to prevent a live cartridge remaining in the barrel. The operating means may be actuated by mechanical, fluid-pressure, or electromagnetic means, and may be embodied in an interrupter gear for firing through an aircraft propeller. Referring to Figs. 1 and 3, the lock 1 is reciprocated by the usual crank and connecting-rod 2 and is normally held in its rearward position by a spring-pressed detent 4 on a rock-shaft 5 carrying an arm 25 which co-operates with a collar 42 on a cable 41 forming part of the control. The firing-pin 7, slidably mounted on the lock, is formed with a step 19 and recess 8 to co-operate with a sear 17 and tumbler 10 respectively. The tumbler 10 has a step 12 with which the tail of the trigger 13 is normally caused to engage by a spring 15 fitted between the trigger and the firing-pin. A trip-piece 16 on a transversely-adjustable bar 26, Fig. 6, is moved into alignment with the trigger 13, against the pressure of a spring 27 by means of a collar 43 on the cable 41, and lever mechanism. A spring-pressed plunger 38 on the cable normally retains the parts in the (non-firing) position shown, wherein, as seen in Fig. 3, a lost-motion gap 5 is provided between the collar 42 and the arm 25, whilst the collar 43 is already in engagement with the lever 33 forming a link in the mechanism for actuating the trip-piece 16. This arrangement ensures that the trip-piece is moved into alignment with the trigger in advance of the movement of the detent 4 to release the lock for operation of the gun, and that this alignment is maintained until after the detent 4 has engaged the lock in its rearward position when firing is discontinued. As shown in Fig. 7, the control may be effected by pressure-fluid admitted to a cylinder 44 actuating a spring-loaded piston, the rod 47 of which engages a rocking lever 48 connected, by a cable 51, to the plunger 38. Figs. 9 and 10 show, in inoperative and operative positions respectively, electromagnetic means for actuating the trip-bar 26 and the lockdetent 4. The armature 58 of a solenoid 54 is carried by a pivoted cranked lever 60, the arm 62 of which moves the trip-bar 26 into its operative position when the solenoid is energized. Another solenoid 55 has its armature 63 mounted on a pivoted cranked lever 65, the arm 64 of which actuates the arm 25 on the spindle 5 of the lock-detent 4, through linkage 68, 69. As shown in Fig. 9, the lever 65 is locked by engagement of its arm 67 with the end of the arm 59 of lever 60 until the latter is rocked, by energization of the solenoid 54, into the position shown in Fig. 10, so as to ensure primary actuation of the trip-bar 26. With the parts in this (firing) arrangement, on de-energization of the solenoids, the fall of the arm 59 of lever 60, to permit of the trip-bar 26 returning to inoperative position, is prevented until the lever 65 has rocked to move the detent 4 into its lock-retaining position. Fig. 11 shows the application of the invention to an interrupter-gear for firing between the blades of an aeroplane propeller. The gear comprises a reservoir 70, generator 71 operated from the engine by a cam 72, and a trigger-control 73 on the gun. The control-valve 74 of the reservoir 70 is actuated from the firing-control 75 by a cable 76, pipes 77, 78 leading from the generator 71 to valve 74 and trigger-control motor 73 respectively. The air-release valve 79 is connected to the motor 73 and reservoir 70 by pipes 80, 81. An extension 82 of the cable 76 is connected to the plunger 38, the arrangement being such that pressure on the firing- control first actuates the valve 74 to control the trigger-motor and then rocks the arm 25 to release the lock.