Patent GB-523371-A (GB)
Title: Improvements in power means for starting and recharging machine guns by retracting the breech bolt
IPC: F41A7/06
Filed: 1939-01-03
Abstract: 523,371. Automatic guns. WAGNER, P. G. Jan. 3, 1939, No. 185. Convention date, Jan. 11, 1938. [Class 92 (ii)] Relates to devices for retracting the breechbolt of a remotely situated gun to feed the first cartridge or to clear a jam, and consists in providing retracting mechanism mounted in association with the cocking handle or other part of the bolt and driven by an electric motor the circuit through which is controlled by a normally-open switch, automatic means being provided to keep the motor circuit closed from the time the said switch is closed until the retractor has completed its cycle of operations. The switch is preferably moved towards its closed position upon pressing the trigger to fire the gun and the device functions to move the breech bolt even if the trigger is afterwards released. The switch is so controlled by the movements of the cocking handle that it remains open while the gun is working normally but its closing movement is delayed so that actual closing occurs only when the gun ceases to fire, the motor then acting automatically to start the gun again. The general lay-out is shown in Fig. 40 for two aircraft wing guns 10, 10a of the Browning machine gun type controlled from a selective firing switch N in the cockpit U. The switch is so arranged that either port or starboard or both guns can be controlled as to firing and recocking. The gun sear 31 is released by a solenoid trigger motor 35 when the firing switch M is closed. Chain gear 121 driven by an electric motor E is provided to retract the cocking handle 45, the movements of the motor being controlled by a brake F operated by a solenoid G. A normally open " priming " switch D has a projection 380 engaged by the cocking handle 45 at the end of each recoil movement to keep contacts 240 open, the switch being moved, subject to the delay caused by a dash-pot, towards its closed position by a solenoid 300 energized when the firing circuit through the trigger motor is established. When the gun stops firing, the " priming " switch D closes and establishes circuits through the solenoid 465 actuating a threepole control switch H for the motor E. The arrangement is such, that the firing circuit is open when the motor is in action and is closed again before the action of the motor is completed. After the motor has acted more than a certain number of times without the gun restarting, a contact breaker, J, the solenoid coil 608 of which is controlled by a thermostatic switch K, comes into action to stop the motor. Lamp 725, wired in the motor switch circuit, indicates when the recharger is working, the lamp flashes corresponding to the number of charger actuations. The parts carried by a reversible-feed wing-type Browning gun are shown in plan in Fig. 4. An adapter frame 51, attached by bolts 16, 17 to the gun, carries adjustably the retractor unit comprising the electric motor E geared to a shaft 93 carrying a sprocket 95 for a chain 121 which also passes over a sprocket 120 adjustable for tightening the chain by a screw 122. The chain carries abutments 133, 134, Fig. 13, which act'in succession on the cocking stud 45 and, after acting, drop behind so as to free the stud for normal working. The solenoid trigger motor 35, Fig. 4, is shown in position for acting on the gun sear. The electric leads 225 connect through a junction box 189 with the motor E and its solenoid brake F and with the delay switch D which is opened by the engagement of stud 45 with a spring plunger 380. The delay switch D, Fig. 18, which acts as a relay to the main control switch H, includes a solenoid' 300 the core 297 of which carries switch blades 292, shown in closed position against contacts 257, and a piston 336 moving 'in an air dash-pot cylinder 340 which permits easy opening of the switch but checks the closing movement except near the end when air escapes through passage 335 to permit of snap action on closing. The main control switch H, Fig. 26, includes a solenoid 465 which moves a spindle core 497 to the position shown when contacts 240 of the switch D are closed. Spring 531 returns the parts when the switch is opened. The three blades of the switch engage in turn fixed contacts to form a feed switch 492, a trigger byepass switch 493 a firing circuit switch 494 and a motor switch 495. Spring plungers 533 engage tapered surfaces on the spindle to retain the switch in open and closed positions, The switch can be manually operated by a handle 530. The circuit breaker J, Fig. 35, includes a solenoid 608 the core 591 of which  carries a switch blade 605. The switch is opened to the position shown by the solenoid when the bimetallic thermostatic  switch K is closed to energize the solenoid coil. Spring-controlled links 649 are connected to the core spindle to provide a snap action to hold the switch in the opened and closed positions. The switch is closed by a handle 604 and the closed position is indicated by a rotary button 660. The main control switch H, the circuit - breaker J. and the thermostatic-switch K are carried in a removable tray 392, Fig. 20, in a control box fitted with sliding terminals 437 to 443.