US2406461A - Machine gun recharger - Google Patents

Description

Aug. 27, 1946. K. M. HAMMELL 2,406,461

MACHINE GUN RECHARGER Filed Dec. 18, 1943 2 Sheets-Sheet l (DP r" 72 INVENTOR. 0% 6/77/61' )7. fiammm-ZZ- Aug. 27,1946. HAMMELL 2,406,461

MACHINE GUN RECHARGER Filed Dec. 18, 1943' 2 Sheets$heet 2 Pr L I 0 8/6! 45 IN V EN TOR. Imrper' M H zmme ZZ Patented Aug. 27, 1946 gleam STATES PATENT OFFICIE MACHINE GUN RECHARGER Kemper M. Hammell, Detroit, Mich, assignor to Eureka Williams Corporation, a corporation of 7 Michigan 13 Claims.

This invention relates to machine gun rechargers and particularly to an automatic mechanism for automatically recharging a machine gun in the event that the bolt thereof fails to retract.

Principal objects of the invention are:

To provide an automatic machine gun recharger;

To provide a new and improved form of automatic machine gun recharger;

To provide a lightweight, efficient, simple and dependable machine gun recharger adapted to be applied to a machine gun on a plane for automatically retracting-the bolt thereof when a dead shell is in the breech of the gun barrel; and

To provide an electrical control circuit fora machine gun recharger adapted to be attached to a machine gun which is operated under the control of an electric circuit.

Other objects and advantages of the invention will be apparent from a consideration of the following specification taken in conjunction with the accompanying drawings, of which there are two sheets and wherein:

Fig. 1 is a side elevational view of a device embodying the invention, with certain parts thereof broken away;

Fig. 2 is a sectional vi w taken generally along the line 22 of Fig. 1, looking in the direction of the arrows;

Fig. 3 is an enlarged view of the switch box and assembly;

Fig. 4 is a diagrammatic illustration of one form of circuit for the recharger; and

Fig. 5 is a diagrammatic illustration of another form of circuit for the recharger.

Referring now to Fig. 1, there is indicated a portion of a machine gun I0 having a bolt l2 which is adapted to reciprocate during the operation of the gun. The bolt I2 is associated with the firing mechanism of the gun and is retracted by the recoil due to the firing of the shell. While these machine guns generally are not operated for more than a few seconds at a time, there are some which will fire as many as seven hundred rounds of ammunition per minute, which means that the bolt 52 may reciprocate as frequently as approximately twelve times per second. The bolt !2 is indicated in the general position to be released upon closing of the firing circuit for firing the shell which is positioned in the breech of the gun barrel and after firing of such shell the recoil will move the bolt I2 to the left along the path indicated by the slot 14 of the gun through which the bolt i2 projects.

A-device embodying the invention consists of a mechanism for automatically retracting the bolt it against the tension of the spring (not shown) thereof if the shell fails to fire, and this mechanism in general comprises a frame i5 adapted to be suitably secured to a machine gun Ill as illustrated in Figs. 1 and 2, said frame forming a support for an electric motor [8, a reduction gear 2%], a plurality of sprockets 22, 24, and 26, a chain 28 operatively associated with the sprockets, a lug 35 on the chain 28, and a switch box 32. In addition to the mechanism disclosed in Fig. 1, a circuit such as that illustrated in Figs. 4 or 5 is employed in connection therewith, and such circuits include certain control mechanism which may be mounted in a box or on a panel elsewhere than on the recharger itself.

The sprocket 22 is mounted on a shaft 35 which projects from the reduction gear 23. The reduction gear 20 may comprise a suitable housing having gearing therein connected to the shaft of the motor i8 and driven thereby, the gearing functioning to drive the shaft 34 at a speed much less than that of the motor during the operation thereof. The teeth of the sprocket 22 operatively engage the links of the endless chain 28 for driving the same, the sprockets Ed and 26 supportingthe chain so that it has a path of movement parallel to the path of movement of the bolt iii. The lug 30 is carried by the chain and has a shoulder 36 which when the chain is driven in the direction indicated by the arrow 98 is adapted to move through a path so as to engage the bolt 62 at the right hand end of slot M and move it to the left for the purpose of retracting the same against the sprin which is conventionally associated therewith.

The lug 39 at one end thereof is pivoted at 38 to the chain, and at the other end thereof has a pin and slot connection M] with the chain so as to not interfere with the passage of the chain over the sprockets. When the 111;; 33 has moved the bolt i2 to its leftmost or retracted position (approximately the lefthand end of the slot I l) the path of the lug 3i: veers away from the path of the bolt [2 so as to disengage the lug 30 from the bolt 12, thereby permitting the spring associated with the bolt to return it in order to fire the shell in the breech of the gun.

The frame It may be suitably formed of sheet metal and have suitable brackets by means of which the reduction gear 29, the motor l8 and switch box 32 may be assembled to the frame l6 itO form a unit, and the unit may be assembled tothe machine gun Iii in the relative position indicated. Cover or guard 5 1 may be removably secured to the frame l6 so as to at least partially enclose the operating mechanism of the unit.

The sprockets 24 and 26 are each individually journaled on a bearing 58 which is carried by an eccentric sleeve 58 which in turn is carried by screw 6!] which in turn is threaded into nut 62 carried by the frame it. Thus the sprockets 24 and 26 may each be adjusted vertically or horizontally and independently of each other so as to properly position the chain 28 and tension the same.

The switch box 32 has arranged therein a double contact switch 64 which will hereinafter sometimes be referred to as a bolt-operated switch, and another switch 68 which will hereinafter sometimes be referred to as a chain-operated switch. The bolt-operated switch 64 includes stationary contacts 88 and movable contacts ill, the contacts 18 being carried by a member which is mounted on a pin or plunger 12. Plunger 12 is reciprocally mounted in the switch box 32 and the righthand end thereof, as illustrated in Fig. 1, is positioned so as to be engaged by the bolt l2 at the end of each retractile stroke thereof. A spring M arranged around one end of the plunger 12 and confined between one wall of the case 32 and the movable contacts IE1 biases the same out of engagement with the stationary contacts 68 so that the bolt switch 94 is normally open.

The stationary contacts 68 preferably are resiliently mounted. A spring 76 may be arranged between the member which carries the movable contacts Hi and a nut F8 secured to the plunger which cooperates with bracket 80 so as to limit the movement of the plunger 12 to the right. The plunger 72 extends through a suitable hole in bracket 8!]. The member which carries the movable contacts 19 is not fastened on the plunger 12 but is positioned thereon by the springs 1 and 15. When the bolt l2 strikes the end of the plunger 12 and thereby moves the same to the left, the switch 64 will be closed for a fraction of a second. The actual time interval that the switch 64 is closed will to some extent depend upon the speed of firing of the machine gun. Under some circumstances it may be desirable to provide some means to retard slightly the opening movement of the switch 64.

Switch 66 includes movable contact 82 and stationary contact 84. This switch is normally open and is adapted to be closed and opened by the chain during each cycle of movement. Movable contact 82 is carried by a switch-operating member 85 having arms 88 and 9B. The member 86 in cross section is U-shaped, and the arm 88 is positioned at one side of the chain 28 while the other arm 99 is positioned on the opposite side of the chain 28. The member 86 is pivoted at 92 and is held in either its open or closed position by a spring 9 3, one end of which bears against the end of the member 86. For example, in the position illustrated, the end of the spring 94 bears against the member 86 to one side of the pivot 92, thereby holding the same in its open position. When the switch is closed the member 86 pivots in a counterclockwise direction, thereby shifting the end of the spring 94 to the other side of the pivot 92 for holding the switch 66 closed. The switch arm 90 is, in the position in which it is illustrated, arranged in the path of a pin 96 which projects laterally from one of the links of the chain. The pin 96 projects toward the machine gun and after the chain has moved a limited 4 amount in its driven direction, which is indicated by the arrow 98, the pin 96 will engage the arm 9i] and shift the member 86 to its other position so as to close the switch 66.

The chain 28 is provided with another laterally extending pin H33 which projects from one of the links of the chain in a direction way from the gun and which pin 569 is adapted to engage the arm 88 and return the member to the position illustrated in Fig. 1 so as to open the switch 68. Thus, after the chain 23 and lug 39 have been moved a small amount from their starting position in which they are indicated in Fig. 1, the pin 96 will by acting on the switch arm close the chain-operated switch 86, and shortly before the chain 28 and lug 38 are returned to their starting position the pin Hit will engage the switch arm 88 and open the switch 66. After the switch 66 is open the inertia of the motor [8 and gearing 251 will permit the lug 31! to return approximately to the position illustrated.

The bolt-operated switch (it is adapted to be closed during the operation of the machine gun by the reciprocation of the bolt l2, and the closing of the switch 64 controls the motor circuit so as to prevent the operation thereof while the machine gun is operating, if the trigger and safety switches thereof are closed as will be further described hereafter. However, should the machine gun fail to operate with the trigger switch and safety switch closed, the bolt i2 will not reciprocate and the switch 64 will remain open, thereby controlling the circuit of the motor so as to initiate the operation thereof. When the motor operates, the chain 28 will be driven in the direction indicated by the arrow 98 and after a relatively small movement of the chain the switch 66 will be closed. The switch 66 controls the motor circuit so as to keep the same closed after the motor begins to operate and until the recharger mechanism completes one cycle of operation.

One cycle of operation consists of movement of the chain 23 sufiiciently so as to move the lug 30 from the position in which it is illustrated in Fig. 1 around past the sprockets 26, 24 and 22 and back to the position illustrated. During this movement the lug 30 will, as previously described, retract the bolt l2 and free it for movement under influence of its spring. The switch 66 closes the motor circuit shortly after the motor begins to operate and will keep the motor circuit closed until opened by the pin I00, even though the trigger and/or safety switch of the machine gun circuit are opened before the mechanism completes one cycle of operation.

The wires of the motor circuit are connected to the switches in the switch box 32, and the switches in the switch box 32 are adapted to be connected by suitable current conductors to the controls, the connector Ill] being provided on the switch box 32 for cooperation with a suitable connector on the current conductors which lead to the controls.

The switches and controls and circuits are diagrammatically illustrated in Fig. 4 wherein the same reference characters have been employed to indicate the switches as described in connection with Fig. 1. Conductor A is connected by the master gun or safety switch HI of the firing circuit for the machine gun to a suitable source of current, and when such switch is closed the conductor A is energized. This conductor A is connected to one side of the motor l8 and a conductor B leads from the other side of the motor I8 to contact 84 of switch 66. This conductor B is adapted to be grounded by the switch 86 when the same is closed so as to close the circuit through the motor. The conductor B is also connected to one of the stationary contacts of a double contact relay switch H4. The other stationary contact of switch H4 is grounded. The movable contact or armature H6 of relay switch H4 is positioned so that the switch H4 is normally closed when the safety switch III is open. Whenever the conductor B is grounded, either through switch 66 or through switch H4, the motor will operate. The conductor A is connected to one end of the coil H8 of the relay of switch H4, while the "other end of V such coil is connected by conductor C to the firing circuit D which includes the firing solenoid H5. A 28-volt, l3-watt lamp I23 is arranged in series with relay coil H8 and between the same and conductor C.

As the switch H4 is closed when the safety switch I I I is open, the circuit through the motor I8 will be closed upon closing of the switch III, but as the coil of relay switch H4 is arranged in parallel with the motor I8 and grounded through the firing circuit D and solenoid H5, the relay will act immediately to open switch H4. While the circuit through the motor I8 is closed momentarily, such circuit is not closed for a sufficient length of time to enable the motor to do any more than turn through several degrees of movement. The coil H8 of the relay preferably has a voltage rating of 4 volts, much less than the rating of the motor circuit which may be 18-28 volts, so that the relay H8 will be excited quickly in order to open the switch H4 very quickly after the safety switch I I I is closed. The resistance of the lamp I28 when the same is cold is comparatively low, but this resistance increases rapidly and considerably when the lamp is lighted, thereby protecting the relay H8 from overload.

When the trigger switch IE3 is closed the machine gun firing circuit D will be closed, thereby actuating the solenoid H5 to release the firing pin thereby initiating the operation of the ma-- chine gun. When the trigger switch I I3 is closed, both ends of the relay coil H3 will be connected through conductors C and A to the positive side of the circuit, thereby tending to neutralize or deenergize the coil I I8. However, as soon as the firing solenoid H5 is actuated, the gun begins firing and the bolt I2 thereof will engage the movable contact of switch 54 and close the same momentarily, thereby grounding the coil H8 and conductor C through conductor E and switch 64. The relay switch H4 is of the delay type and is adapted to be energized rapidly relative to its time of deenergization. A timing slug I I1 is pro- Vicled on relay H8 to delay the drop out thereof. That is, during the time that the bolt-operated switch 54 is closed, which may be for .005-.010 second per cycle, the relay coil H8 must be excited sufilciently in order to hold switch I I4 open until the next cycle of excitation, and the characteristics of the relay coil H8 must be such that approximately of a second must elapse after the circuit through the relay is opened before the armature HE is released. Because of this the switch H4 will remain open during the reciprocation of the bolt I2. As soon as such reciprocation stops the relay coil I I8 will become deenergized and permit the closing of switch H4,

thereby closing the circuit through the motor I8 and initiating the operation thereof. A defective shell in the breech of the machine gun is usually the cause for the failure of the bolt I2 to reciprocate.

The switch 66 will be closed as previously described shortly after the motor begins operating and will remain closed until shortly before the lug 38 completes one cycle of operation. Thus if the trigger switch is opened, which would deenergize the conductor 0, the motor circuit would be closed from conductor A through the switch 66, and in this way the recharger mechanism will complete a cycle, once started, irrespective of whether or not the trigger switch is open during a cycle, so that the next time that the trigger switch is closed the machine gun will be cooked for immediate firing.

Thus one form of my invention comprises a recharger for an electrically operated machine gun I0 adapted to be fired by the closing of a firing circuit D, said circuit including a master switch III, a firing switch H-3 and a firing solenoid H5, said firing switch being in series with said master switch and operable upon closing, when said master switch Hi is closed, to energize said firing solenoid H5, thereby to initiate the normal operation of the machine gun (assuming that the gun is loaded and provided with means such as a cartridge belt for supplying live ammunition thereto), said gun having a reciprocable bolt I2 adapted to be retracted normally by the recoil of a fired shell, said recharger comprising a member 38 movable through a path and in its movement through said path being engageable with said bolt I2 for retracting the same and being adapted to release said bolt in its retracted position, an electric motor I8, a driving connection between said motor and member 38 for moving the latter through its path during operation of said motor, a motor circuit A, B having its high potential end connected to said firing circuit D between said switches, a time delay relay including a switch H4 associated with the grounded end B of the motor circuit and operable to open the motor circuit upon closing of said master switch III, one end of the relay coil H8 being connected to the high potential end A of the motor circuit, the other terminal of the relay coil I I8 being arranged, upon closing Of said master switch III, to be grounded through a lamp bulb I28 in series with said firing solenoid H5, when said firing switch H3 is open, for operating said relay switch H4 to open said motor circuit, said other terminal of said relay coil H8 also being arranged to be grounded through a bolt-operated switch 64, periodically momentarily closed by and during the reciprocation of said bolt I2, (during normal operation of said gun) when the firing switch H3 is closed, for energizing said relay coil H8 sufi'iciently to keep said switch I I4 from closing, thereby to keep said motor circuit AB open, a mechanically operated switch 66 adapted to be closed by the cycling of said member 30 and arranged upon closing to ground said motor circuit AB, the voltage rating of said relay coil H8 being materially less than that carried by said motor circuit AB and the initial resistance of said lamp bulb I28 being Suificiently low so that upon closing of said master switch III, the relay coil H8 will be energized at 'a sufiiciently rapid rate so that the relay switch H4 will open the motor circuit before the motor makes an appreciable starting efiort, the characteristics of the lamp bulb I28 being such that upon lighting, the resistance thereof increases thereby limiting the current in the relay coil "7 H8 to a safe value, the closing of said firing switch I I3 functioning to energize the firing solenoid H and to deenergize said relaycoi1.II8 and lamp bulb I 20, the operation of said machine gun and reciprocation of the, bolt I2 thereof pursuant to the energization of solenoid I I5 functioning to periodically close said bolt-operated switch 64 sufficiently frequently to maintain said coil IE8 energized sufficiently to maintain said relay switch II 4 open, said time delay relay being constructed to allow a rapid opening of the relay switch. I I4 and a relatively slow closing thereof, the period of the closing time of said relay being appreciably greater than the period of operation of the machine gun, the coil II8 of the relay being wound so as to have asufliciently low impedance that a sufiiciently high excitation will be produced in the coil upon the periodic momentary closing of the bolt operated switch, failure of said gun to operate when said firing switch is closed deenergizing the coil H8 of said relay and permitting said switch M4 to close said motor circuit thereby initiating a cycle of operation of said recharger to effect the. retraction of said gun bolt, said mechanically operated switch being closed by the cycling of said memebr 30, to keep said motor circuit closed until said recharger completes said cycle of operation, said member being operable during said cycle of recharger operation to retract said bolt and free the same, in order to restart the operation of said machine gun if said firing switch H3 and motor switch III are closed, restarting of the operation ofsaid-machine gun causing the bolt I2 thereof to close said boltoperated switch 64 to ground said relay coil H8 in order to keep open said motor circuit after said recharger has completed one cycle of operation.

In the modified form of the invention using the circuits illustrated in Fig. 5, in lieu of that illustrated in Fig. 4, the machine gun is adapted to be fired by the closing of firing circuit D, said circuit including master switch III, firing switch I I3 and firing solenoid I I5, said firing or trigger switch being in series with said master switch and operable upon closing, when said master switch III is closed, to energize firing solenoid H5, thereby to initiate normal operation of the machine gun (assumingthat the'gun is loaded and provided with means such as a cartridge belt for supplying live ammunition thereto) and reciprocation of the bolt I2 thereof. I

The motor I8 is operatively arranged in a motor circuit FG having its high potential end connected to the firing circuit D between switches III and H3. Certain parts of these circuits duplicate parts of the circuits illustrated in Fig, 4 and in such cases the same reference characters as used in Fig. 4 have been employed in Fig. 5 to designate corresponding parts. The motor circuit is adapted to be grounded through relay switch 30 or through the mechanically operated switch 66, which as previously indicated is normally open, but closed during cycling of the recharger. Relay switch I30 form par-t of a time delay relay means which includes a low impedance circuit I32 and a normal impedance circuit I34 connected in parallelto the high potential side of the motor circuit. Low impedance circuit I32 includes a relay coil I36 (which may have a resistance of 1.4 ohms) which is arranged in series with coil I38 (which may have a resistance of 200 ohms) of the normal impedance circuit I34. Lowimpedance circuit I32 is'ada'pted to .begrounded either through bolteoperat'ed switch Switch 64.

6'4, periodically momentarily closed by and 'during the'reciprocation of bolt I2, (during normal operation of the machine gun) or through serially arranged switches I and I42. Switche I30 and I40 are simultaneously opened by energize.- tion of coil I33 and circuit I32, which occurs (starting with the. circuits arranged as illustrated) immediately upon energization of the motor circuit FG due to the closing of master switch III. Thus the low impedance circuit I32 is energized only momentarily. Normal impedance circuit I34, arranged in parallel with circuit I32, is energized simultaneously therewith being grounded through switch I 4-4, the energization of coil I38 functioning to keep switches I33'and I40 open after. the low impedance circuit is opened.- As

thus arranged the circuits are in what might be .firing solenoid I I5, thereby initiating operation of the machine gun. If live ammunition i in the gun, the gun will operate thereby causing reciprocation of bolt I2, which in turn will periodically momentarily close switch 54. The closing of the firing circuit D will also energize the circuit Kin which switch I46 (now closed) is arranged, circuit K having its high potential side connected to the firing circuit D and being grounded through pullin coil I48 (100.chms) of. a-control relay means which further includes lock-in coil I (240 ohms) and switches. I42 and I44. Energization of coil I48 will open switches I42 and I44, thereby opening the normal impedance circuit I34 and deenergizing coil I38(low impedance circuit I32 previously having been'deenergized by opening of switch I40). The coil I43 operates to open switches I42 and I44 before the bolt I2 closes switch 64, but the coils I36 and I38 of the time delay relay are provided with a timing slug or means I52 Which'holds open the switches I30 and I4!) until the low impedance circuit is grounded through the bolt-operated switch 64; that is, the timing slug I52 delays the deenergization of coil I33 for a period of time (a fraction of a second) until the coil I36 is energized by the closing of The coils I36 and I33 of thetime delay relay are constructed to allow a rapid opening of the relay switches I30 and I 40 and a relatively slow closing thereof, the period of the 010sing time of the relay being appreciably greater than the period of operation of the machine gun. The grounding of the low impedance circuit I32 through the bolt-operated switch 64 functions during normal operation of the machine gun to keep the pull-in coil I36 energized sufliciently to keep the switches I 30 and I40 open and the switch I46 closed.

So long as the switches 63 and I30 are open, the motor circuit FG will be open, and this condition will prevail during normal operation of the machine gun. If after closing of the trigger switch I I3, the gun fails to start or stops, the boltoperated switch 64 will remain open, thereby deenergizing the low impedance circuit I32, as a result of which the coil I36 of the time delay relay will become deenergized, thereby allowing switches I33 and I40 to close and switch I46 to open. The closing of switch I30 will close the motor circuit FG, thereby initiating operation of the motor which, through the mechanism previously described, will retract the'bolt I2, as a consequence of which a new piece of ammunition will be inserted in the gun barrel for firing.

The switches of the time delay relay are set so that the switches I30 and I40 will close before switch I46 opens. The closing of switch I40 will close the low impedance circuit I32 and ground the same through the lock-in coil I50. The resulting energization of the lock-in coil I50 will function to keep the switches I42 and I 44 open even though the coil I48 might become deenergized due to the opening of the switch H3 or switch I46. The lock-in coil I50 has a resistance of about 240 ohms so that when the low impedance circuit I32 is grounded through such coil I50, the latter will draw practically all of the current in the circuit, with the result that the coil I35 will not be energized sufiiciently to open the switches I30 and I40 or to close the switch I 45. Between the switch E30 and the ground, a resistance I 60 of one ohm is provided in order to reduce the load across the contacts of the switch I 30 during the opening and closing thereof. When the switch I30 closes, the operation of the motor will be initiated to begin the cycling of the recharger, but as hereinafter explained the motor will be operated under substantially no load until after the chain-operated switch 55 closes, which occurs as soon as the chain 28 has moved sumciently to engage and actuate the switch arm 90 by the pin 96.

Toward the end of the cycle of operation of the recharger the pin I will, through engagement with the arm 88 of the switch 66, open the same after the recharger has been relieved of the load of the bolt I2. The retraction of the bolt I2 by the recharger will close the switch 54 before the switch 66 is opened as just described. Such closing of the switch 54 will thereby close the circuit through the low impedance coil I36, thereby energizing the same to open the switches I30 and I40 and close the switch I46, such switch I46 closing before the switches I30 and I40 open. While the lock-in coil I50 will be deenergized by the opening of switch I 40, the previous closing of switch I46 will close the circuit K through the pull-in coil I48. As a result of the foregoing actions following the closing of the switch 64 by the bolt I2 upon the retraction thereof by the recharger, the circuits will be restored to their stand-by position. If the new shell injected into the gun barrel is a piece of live ammunition, the normal operation of the gun will be resumed with the result that the bolt I2 will periodically momentarily close the switch 54. thereby closing the low impedance circuit I32 sufficiently frequently to keep the coil I 36 energized in order to keep the switches I30 and I40 open and the switch I46 closed. It will be observed that the motor circuit is closed through the switch 65 in order to permit the recharger to complete its cycle of operation and that the opening of firing switch I I3 during a cycle will not interfere with the completion thereof. The opening of switch I46 will prevent an inductive reactance f om the firing solenoid II5 from momentarily deenergizing the coil I48 of the control relay under certain conditions.

While the circuits disclosed herein form a part of a recharger mechanism, I contemplate that such circuits may be employed in other types of cyclic mechanisms for restarting the operation thereof. In its broadest aspect the invention disclosed and claimed herein comprises a mechanism operable at a substantially constant cyclic rate (the machine gun), electric means (the firing solenoid H5 and circuit therefor) to initiate operation of such mechanism, restoring means electrically operated and mechanically operable (the motor driven member to reestablish motion in said mechanism when said cyclic rate is interrupted due to accidental cause, electrical discriminating means (the time delay relay and the low impedance circuits) actuated at least once per operating cycle of said mechanism and operable to initiate functioning of said restoring means, interlocking means (lock-in coil I50, switches I42 and 144, and the chain operated switch 65) associated with said discriminating means and operable to cause the completion of the cycle of the restoring means once the discriminating means has initiated operation thereof, and unlocking means (switch 54, coil I which operate when the bolt I2 is retracted by the member 30 to cause the deenergization of the lock-in coil I and the opening of switch I42) associated between said discriminating and interlocking means and operable to restore said discriminating and interlocking means to a stand-by condition.

If the coil I48 is provided with some time delay action to delay the drop-out thereof, then it becomes immaterial whether the switch I46 closes before the switches I30 and I40. This time delay for the coil I48 may be obtained by utilizing a timing slug, such for example, as the type employed in connection with the coil I 38 as indicated by the reference character I52.

While the invention has been described with some detail, it is to be understood that the description is for the purpose of illustration only and is not definitive of the limits of the inventive idea. The right is reserved to make such changes in the details of construction and arrangement of parts as will fall within the purview of the attached claims.

I claim:

1. A recharger for an electrically controlled machine gun adapted to be fired by the closing of a firing circuit, a trigger switch operable for closing said firing circuit, said machine gun having a reciprocable bolt adapted to be retracted normally by the recoil of a fired shell, said recharger comprising a member movable through a cycle and in its movement through said cycle being engageable with said bolt for retracting the same and being constructed and arranged to release said bolt in its retracted position in order to restart the operation of said gun if said firing circuit is closed, an electric motor, a driving connection between said motor and member for moving the latter through its cycle during operation of said motor, an electric circuit in which said motor is included, a relay including a switch in said motor circuit and a coil, one side of said coil being connected to the high potential side of said motor circuit, said coil upon being energized functioning to open said switch in said motor circuit, the closing of said firing circuit by said trigger switch functioning to initiate the operation of the machine gun and the reciprocation of said bolt, means operable upon the closing of said firing circuit to deenergize said coil, the drop out time of said relay coil being greater than the period of reciprocation of said bolt, and means including a circuit for said coil having a normally open switch provided with an actuating member positioned in the path of said bolt and constructed and arranged to be actuated thereby normally to close said switch momentarily and periodically during the reciprocation of said bolt for energizing said relay coil-sufficiently frequently to keep said relay switch open, failure of said gun to operate when said trigger switch is closed causing the deenergization of said coil and the resultant closing of said motor circuit, thereby to initiate a cycle of operation of said recharger to efiect the retraction of said gun bolt.

2. The construction defined in claim 1 in which a safety switch is provided in said firing and motor circuits for opening the same. 7

3. The construction defined in claim 1 in which means are provided to keep the motor circuit closed if the firing circuit is deenergized before the recharger has completed said cycle of operai tion.

4. A recharger for an electrically controlled machine gun adapted to be fired by the closing of a firing circuit, a trigger switch operable for closing said firing circuit, said machine gun having a reciprocable bolt adapted to be retracted normally by the recoil of a fired shell, said recharger comprising a member movable through a cycle and in its movement through said cycle being engageable with said bolt for retracting the same and being constructed and arranged to release said bolt in its retracted position in order to restart the operationof said gun if said firing circuit is closed, an electric motor, a driving connection between said motor and, member for moving the latter through its cycle during operation of said motor, an electric circuit in which said motor is included, a relay including aswitch in said motor circuit and a coil, one side of said coil being connected to the high potential side of said motor circuit and the other side of said coil.

being grounded through said firing circuit when said trigger switch is open, said coil being energized immediately upon the closing of said motor circuit, to open said switch in said motor circuit, the closing of said firing circuit by said trigger switch functioning to initiate the operation of the machine gun and the reciprocation of said bolt, means operable upon the closing of said firing'circuit to deenergize said coil, the drop out time of said relay being greater than the period of reciprocation of said bolt, and means including a circuit for said coil having a normally open switch therein provided with an actuating member positioned in the path of said bolt and constructed and arranged to be actuated thereby normally to close said switch momentarily and periodically during the reciprocation of said bolt for energizing said relay coil sufficiently frequent- 1y to keep said relay switch open, said relay switch operating to close said motor circuit upon failure of said bolt to reciprocate when said firing circuit i closed.

5. The construction defined in claim 4 in which closed if the firing circuit is opened before the motor has driven said member through a complete cycle. V

6. The construction defined in claim 4 in which a safety switch is provided in said firing and motor circuits for opening the same.

7. A recharger for an electrically controlled machine gun adapted to be fired by the closing of a firing circuit, a trigger switch operable for closing said firing circuit, a safety switch in said firing circuit ahead of said trigger switch, said machine gun having a reciprocable bolt adapted to be retracted normally by the recoil of a fired shell, said recharger comprising a member movable through a, cycle and in its movement through said cycle being engageable with said bolt for retracting the same and being constructed and arranged to release said bolt in its retracted position in order to restart the operation of said gun if said switches are closed, an electric motor, a driving connection between said motor and memher for moving the latter through its cycle during operation of said motor, an electric circuit in which said motor is included, the high potential side of said motor circuit being connected to said firing circuit between said switches, a time delay relay having a'switch in said motor circuit and a coil, one side of the coil of said relay being connected to the high potential side of said motor circuit, said coil being energized by the closing of said safety switch immediately to open said relay switch in the motor circuit, the closing of said firing circuit by said trigger switch functioning to initiate the operation of the machine gun and the reciprocation of said bolt, means operable upon the closing of said firing switch to deenergize said coil, the drop out time of said relay coil being greater than the period of reciprocation of said bolt, means including a circuit for said coil having a normally open switch therein provided with an actuating member positioned in the path of said bolt and constructed and arranged to be actuated thereby normally to close said switch momentarily and periodically during the reciprocation of said bolt for energizing said relay coil sufiiciently frequently to keep said relay switch open, failure of said gun to operate when said trigger and safety switches are closed causing the deenergization of said coil and the resultant closing of said motor circuit, thereby to initiate a cycle of operation of said recharger to efi'ect the retraction of said gun bolt.

, 8. The construction defined in claim 7 in which shell, said recharger comprising a member movable through a cycle and in its movement through said cycle being engageable with said bolt for retracting the same and being constructed and arranged to release said bolt in its retracted position in order to restart the operation of said gun if said firing circuit is closed, an electric motor, a driving connection between said motor and member for moving the latter through its cycle during operation of said motor, an electric circuit in which said motor is included, a time delay relay having a switch in said motor circuit and a coil, one side of the coil of said relay being connected to the high potential side of said motor circuit and the other side of said coil being grounded through said firing circuit when said trigger switch is open, an electric lamp in series with said coil and arranged in the connection between said coil and said firing circuit, said on the closing of said firing switch to deenergize said coil, the drop out time of said relay being greater than the period of reciprocation of said bolt, and means including a circuit for said coil having a normally open switch therein provided with an actuating member positioned in the path of said bolt and constructed and arranged to be actuated thereby normally to close said switch momentarily and periodically during the reciprocation of said bolt for energizing said relay coil sufiiciently frequently to keep said relay switch open, said relay switch operating to close said motor circuit upon failure of said bolt to reciprocate when said firing circuit is closed, and means to keep the motor circuit closed if the firing circuit is opened before the motor has driven said member through a complete cycle, said'last-mentioned means comprising a circuit for said motor circuit having a normally open switch therein provided with an actuating member engaged and actuated by a part of said bolt engaging member at the beginning of said cycle for, closing said motor circuit and at the end of said cycle for opening said motor circuit.

10. A recharger for an electrically controlled machine gun adapted to be fired by the closing of a firing circuit, a trigger switch operable for closing said firing circuit, a safety switch in said firing circuit ahead of said trigger switch, said machine gun having a reciprocable bolt adapted to be retracted normally by the recoil of a fired shell, said recharger comprising a member movable through a cycle and in its movement through said cycle being engageable with said bolt for retracting the same and being constructed and arranged to release said bolt in its retracted position in order to restart the operation of said gun if said switches are closed, an electric motor, a driving connection between said motor and member for moving the latter through its cycle during operation of said motor, an electric circuit in which said motor is included, a time delay relay including a coil and a switch associated with the motor circuit and operable to open the motor circuit, one end of the coil of said relay being connected to the high potential end of the motor circuit, the other terminal of the relay coil being arranged to be grounded through a lamp bulb in series with the firing circuit whereby said relay switch may operate to open said motor circuit, said other terminal of said relay coil also 'H' being arranged to be grounded through a bolt operated switch periodically momentarily closed by and during the reciprocation of said bolt for energizing said relay coil sufiiciently to keep said relay switch from closing thereby to keep said :1

motor circuit open, the electrical rating of said relay coil being materially less than that of said motor circuit and the initial resistance of said lamp bulb being sufficiently low so that upon closing Of the relay circuit, the coil will be energized at a rapid rate to open the motor circuit, the characteristics of the lamp bulb being such that upon lighting, the resistance thereof increases thereby limiting the current in the relay coil to a safe value, the closing of the firing switch functioning to energize the firing circuit and to deenergize said relay coil and lamp bulb, said time delay relay being constructed to allow a rapid opening of the relay switch and a relatively slow closing thereof, the period of the closing time of said relay being appreciably greater than the period of operation of the machine gun, the coil of said relay being wound so as to have a suificiently low impedance that a sufficiently high excitation will be produced in the coil upon the periodic momentary closing of said bolt operated switch, failure of said gun to operate when said firing switch is closed deenergizing the coil of said relay and permitting said relay switch to close the motor circuit thereby initiating a cycle of operation of said recharger to efiect the retraction of said gun bolt.

ll. The construction defined in claim 10 in which a mechanically operated switch is provided for closing the motor circuit, said mechanically operated switch being closed by and during the cycling of the recharger.

12. A. recharger for an electrically controlled machine gun adapted to be fired by the closing of a circuit, a trigger switch operable for closing said firing circuit, a safety switch in said firing circuit ahead of said trigger switch, said machine gun having a reciprocable bolt adapted to be retracted normally by the recoil of a fired shell, said recharger comprising a member movable through a cycle and in its movement through said cycle being engageable with said bolt for retracting the same and being constructed and arranged to release said bolt in its retracted position in order to restart the operation of said gun if said switches are closed, an electric motor, a driving connection between said motor and member for moving the latter through its cycle during operation of said motor, an electric circuit in which said motor is included, said motor circuit being arranged to be closed through a switch of a time delay relay means when the safety switch is closed, said time dela relay means including a low impedance circuit, a normal impedance circuit connected to the high potential side of said motor circuit and a coil, the coil of said relay comprising a low impedance coil in said low impedance circuit and a normal impedance coil in said normal impedance circuit, said low impedance circuit further including a switch constructed and arranged to be opened simultaneously with said relay switch in said motor circuit by energization of said low impedance circuit, a fire control relay including a switch for closing said low impedance circuit and a lock-in coil through which said low impedance circuit may be grounded when said last-mentioned switch is open, said low impedance coil functioning to open the low impedance circuit and the motor circuit immediately upon the closing of said safety switch, said control relay further including a switch in said normal impedance circuit for closin the same so as to energize said normal impedance coil, said last-mentioned coil functioning to keep said switches of said time delay relay in said motor and low impedance circuits open, said control relay including a pull-in coil which is arranged in a circuit that is energized upon the closing of said firing switch, said pull-in coil functioning to open the switches of said control relay so as to open the normal impedance circuit, a bolt operated switch constructed and arranged upon closin to close the low impedance circuit, said bolt operated switch being constructed and arranged to be e closed periodically momentaril by the reciprocation of the bolt during the normal gun operation, means to prevent the deenergization of the coils of said time delay relay after opening of the normal impedance circuit and before said low impedance circuit is closed through said bolt operated switch, the drop out time of said time delay relay being greater than the period of reciprocation of said bolt, closing of said bolt operated switch functioning to energize the low impedance coil sufficiently frequent to keep said relay switch operate when said trigger and safety switches are.

closed permitting the deenergization of the coil of said time delay relay and the closing of said relay switch in said motor circuit. 7

13. The construction defined in claim 12 in Which the deenergization of the low impedance circuit permits the closing of the low impedance circuit through the lock-in coil of the control relay so as to keep the motor circuit closed during 10 thecy'cling of the recharger, the resistance of the:

low impedance coil being materially less than that of the lock-in coil of the control relay so that when the low impedance circuit is grounded through said lock-in coil said low impedance coil will not be energized suficiently to open the switches of the time delay relay in either of the motor or low impedance circuits.

KEMPER M. HAMMELL.

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