Oct. 22, 1946. 2,409,623 H. c. GRANT, JR GUN CHARGER Filed Nov. 14, 1941 .4 Sheets-Sheet l 1_ _É `__ ___ _ ____ -`__ .___ ___ M22/rá ~ BY ~ ì ATTORNEY ' ì t. 22, i946. H. c. GRANT, JR GUN CHARGER 2,409,623 Filed Nova, 14; 1941 4 sheets-sheet a [1474 INVENTOR Hmz? ¿.*óìdzz?dr BY ATToRN _ Oct. 22, 1946; H. c. GRAN-lv', JR A 2,409,623 GUN CHARGER Filed Nov. 14, 1941 _, /52 ' 4 sheets-sheet 4 I /75 ~ "455 , I ATTORN Patented Üct. 22, 1946 UNITED man?. STATES PATENT GFFICE ' 2,409,623 GUN CHARGER Harry C. Grant, Jr., New York, N. Y., assignor to I Specialties Development Corporation, Bloom field, N. J., a corporation of New Jersey Application November 14, 1941, Serial No. 419,053 8 Claims. (Cl. 89---1) l 2 The present invention relates to automatic ma -chine guns and the like, and more particularly to devices, known as gun chargers, for initiating the operation of a gun charging mecha vice which is accurately controlled, can stand rough usage and is adapted to return the gun to ñring action in a minimum period of time. An object of the present invention is to pro vide an improved gun charger which is light in nism which normally is operated by the recoil resulting from the explosion of cartridges. In automatic machine guns, for example, of the “Browning” type, release of the ñring pin, weight and occupies a amount of space. Another object is to provide a gun charger hav ing a minimum number of mechanical parts. either mechanically or electrically, fires a car Another object is to provide a gun charger tridge in the chamber of the barrel of the gun. 10 adapted to be mounted on either side of a ina The resulting recoil causes a bolt mechanism or chine gun, as may be decided in the ñeld or prior charging mechanism to move backward to with to the installation of the guns in airplanes, tanks or other craft. . . draw the exploded or fired cartridge case and, at the same time, to present a Succeeding >cartridge Another object is to provide a gun charger on a cartridge feed belt adapted to be fed into the 15 which is readily adjustable to compensate for chamber. After the bolt mechanism has been variance in the stroke of the guns, whereby the fully retracted, it returns to the iiring position gun charger may be transferred from one gun to and in the course of its return stroke ejects the empty or iired cartridge case and feeds the suc another. Another object is to provide a gun charger hav ceeding cartridge into the chamber. While the 20 ing a minimum number of parts which are in op eration while the gun is firing normally. firing pin is released, the gun iires when the bolt Another `object is to provide a gun charger returns to the full forward position. If no trouble develops, the cycle of operation of the adapted to be operated by a high pressure fluid charging mechanism is repeated at a rate of be medium and apply a force of a suiiicient mag nitude to initiate the movement of the bolt or tween about 400 and 1G00 shots per minute. charging mechanism. Once the gun has been loaded, iiring should be Another object is to provide a detecting mech automatic unless any one of a number of possible anism adapted to be used in connection with gun difñculties occurs. For example, a shell may fail chargers, which is inactive during the normal to explode or may fail to develop a recoil force sufficient to move the bolt mechanism through 30 motion of the operating mechanism of the gun the shell ejecting and loading cycle. Also, the andA is operative in response to the lack of such normal motion. charging mechanism may fail to extract the car tridge from the belt or a shell may jam in the Another object is to provide an accurate de- ' barrel and resist removal on the ñrst attempt. tecting mechanism for gun chargers and the like In addition, any one of the many elements of the 35 which can withstand shock and vibrations With bolt or charging mechanism may fail momentar out getting out of adjustment or repair. ily to perform its designed function and prevent Another object is to provide an electrically op the ejecting and loading cycle from being prop erated detecting mechanism comprising a mini erly performed. In the event that the bolt or mum number of parts, electrical connections and charging mechanism fails to function properly 40 wiring circuits. for any of the foregoing reasons, it is necessary Another object is to provide a detecting mech to pull the bolt mechanism fully backward and anism for gun chargers which operates in re then release it-to complete the ejecting and re spense to failure of the gun to fire regardless of loading operation normally carried out by the the position of the bolt or charging mechanism 45 when stoppage occurs. gun itself after it has once been ñred. Another object is to provide a gun charger Heretofore, devices known as gun chargers have been employed for mechanically actuating adapted to operate the bolt or charging mech the charging mechanism in response to failure anism through at least one complete cycle of op of the gun to continue firing. None of these de eration~ vices has been found fully satisfactory because 50 Another object is to provide a gun charger of the complexity of design, unreliability of per having a detecting mechanism adapted to put the gun charger back into operation within substan formance and relatively long delay occasioned be fore putting the gun into action again. tially the same period of time required for one The present invention aims to provide an irn cycle of operation of the gun, whereby the gun proved, practical, and reliable gun charging de 55 remains` out` of action a minimum length of time. 2,409,623 4 larly to Figure l, there is shown a machine gun, A further object is to provide a gun charger havinCf a detecting mechanism adapted to be cut for example, of the “Browning” type which, gen erally, comprises a barrel assembly lll and a bolt mechanism or charging mechanism (not shown), which is located in a housing or casing Il. The charging mechanism is of the usual design and includes a number of slidably movable or recip rocating parts which are moved rearwardly by the recoil resulting from the explo-sion of car l() tridges and which are moved forwardly by a re panying drawings, wherein: turn spring or the like. During reciprocation of Figure 1 is a diagrammatic side view of a ma these parts, the operating cycle of the gun is car chine gun having a gun charger attached thereto. ried out. This cycle comprises removing a car Figure 2 is a schematic View of the essential tridge from the cartridge belt and inserting it operating parts of a gun charger, illustrating an out of operation when the gun charger initiates operation of the bolt or charging mechanism and adapted to remain out of operation until the gun is restored to normal firing operation. Other and further objects, not specifically enu merated above, will be apparent when described in greater detail in connection with the accom embodiment of the invention. into the chamber, firing the cartridge, withdraw ' Figure 3 is a wiring diagram of the electrical circuits of a gun charger, in accordance with the invention. Figures ¿i and 5 are simpliñed wiring diagrams, illustrating the operation of the detecting mech anism of the gun charger. Figure 6 is a simpliñed Wiring diagram, similar to Figures ¿i and 5, illustrating the detecting , mechanism cut out of operation while the gun charger moves the bolt or charging mechanism. Figures 7, 8 and 9 are simplified wiring dia grams, illustrating a modified circuit for the de tecting mechanism of the gun charger. In accordance with the invention, it has been found that the foregoing objects may be accom 30 plis'hed by providing a detecting and initiating device, suitabie for machine guns and other pur poses, having electrical detecting and controlling means which is operable in response toa current pulse of a predetermined minimum time interval, and which is not aiîected'by current pulses of less than the minimum time interval. In a .practical embodiment, illustrative of the invention, such a device, generally, may comprise a circuit> supplied with a continuous current from a direct current source; relay means or the like ing the fired cartridge from the chamber and ejecting the empty cartridge case from the hous ing ll. Since the construction and operation of such a charging mechanism is well known to those skilled in the art, a detailed illustration and description is not believed to be necessary. In the event the normal operating or iiring cycle of the gun is interrupted and iiring ceases, the gun must be recharged or recocked before it can be put in operation again, To accomplish this, a gun charger l2, suitably encased, may be attached to either side of the gun housing H and may be operatively connected to the bolt or charging mechanism by a bolt or stud member hl which extends through an elongated slot l5 in the housing l! and is movable with the recipro cating parts of the charging mechanisml The gun charger l2 preferably is operated by a fluid pressure medium, such as high pressure carbon dioxide, air or any suitable gas stored in a pres sure vessel I6 and adapted to be supplied to the gun charger by a hose or tube l1. A cable i8 containing electrical conductors for the electrical devices of the gun charger is attached to one end ` of the gun charger. In Figure 2, the essential operating parts of the gun charger are illustrated schematically. connected in the circuit, the relay means being The reciprocating bolt or stud member E4 or the constructed and arranged to be actuated by a gun charging mechanism is shown adjacent and current rpulse of a predetermined minimum time interval in either direction, but being unaffected 45 in the path or a ram E9, or tl e like, adapted to engage the member 615 and move it towards the by current pulses 0f less than Vthe minimum time left along the slot l5, that is, rearwardly with interval; and means associated with the bolt or respect to the gun, in the event the gun ceases charging mechanism of a machine gun for peri ñring during operation thereof. The ram i0 odically interrupting the continuity of a portion oí vthe circuit, whereby the relay means is sub 50 comprises a cylinder 2Q and a slidable member 2l_ adapted to be telescoped in the cylinder 2i?. jected to current pulses of less than the minimum V time interval during normal movement of the bolt The member 2l has a piston 22 at one end and a ramming head 24 at the other end for moving or charging mechanism, Thus the relay means, the bolt or stud member it. during continuous iiring of the gun, is not The ramming head 2t >has a recessed end face affected by the periodically interrupted current 55 25 for engaging an adjustable stop 26 threaded or current pulses of less than the minimum Vtime through the bolt or stud ifi. The stop ‘25 may be interval, but upon failure of normal movement utilized to accurately determine the distance the of the bolt or charging mechanism, the inter bolt or stud i/«l and the slidable parts of the ruption of the current ceases for a sui‘ñcient dura tion to permit current of a substantially continu 60 charging mechanism can be moved rearwardly by the ram. The ramming head may be slidably ous character or a current pulse of the minimum mounted on a pairV of spaced apart parallel guide time interval to energize the relay means and tubes or rods 2.7 which extend respectively effect operation thereof. The invention further contemplates the use of such a detecting and con trolling device in combination with a fluid pres through guide apertures in outwardly extending 65 lugs or ears 29 carried by the head 2li. One of the lugs 29 of the head 24 may have a down wardly depending extension 3B provided with a charging mechanism through its operating cycle. pair of arms 3l and 32 which .extend in a direc In addition, the gun charger may be provided tion parallel to the movement of the head and with means for rendering the detecting and con trolling device inefîective when the ram com 70 are adapted to operate devices described herein after. mences ’to function and may be provided with sureV operated ram for mechanically moving the other cooperating devices and improvements which will 'be pointed out more particularly here inafter. Referring to the drawings, and more particu The slidable ram Vmember 2l, preferably, is moved out of the cylinder 2D bysupplying a iiuid pressure medium in back of 'the .piston 22 and is 75 returned to the position shown in Figure 2 by 2,409,623 5 6 suitable springs 34. A valve 35 is utilized to conj trol the admission and the exhaust of the pres dium is admitted to the cylinder 2li to move the ram member 2| outwardly. The head 24 of the sure medium to and from the cylinder. This slidable ram member, as it moves along its path, valve may comprise a body having a chamber engages the stop 26 of the bolt'l or stud I4k wherever it may be along the slot I 5, and moves therein; a valve seat 36 in communication with thechamber and an inletport 3l connected to the bolt I4 and the reciprocating parts of the the pressure medium supply hose Il; a second charging mechanism to their extreme rearward or leftward position. valve seat 38 in communication with the cham When the ramming head approaches its rear ber and an exhaust port 33; a _valve member 40 in the chamber; and a conduit 4I leading from 10 most position, it is desired to shut off the supply of pressure medium and exhaust the cylinder. This the chamber to the cylinder 2B. When the valve is accomplished by the arm 3l which engages, for member 45 abuts the seat 35, the inlet port 3'.' example, the ilange 56 of the rod 52 and pushes «the is shut off and the exhaust port 35 is open to rod through the collar 55 to reload the spring 55 enable pres-sure medium in the cylinder 20 to es cape, whereby the springs 34 may rapidly re 15 and cause the projections 60 and 6I to reengage. turn the slidable member 2l to the position shown .in Figure 2. When the valve member 45 is moved towards the right and abuts the seat 39, the ex haust port is closed and the inlet port is opened to admit pressure medium to the cylinder. The valve member 4i! is provided with a stem 42 extending outwardly through the valve body and adapted to be engaged by a suitable valve con trolling device about to be described. The device for controlling the valve may com prise an arm or linger 44, for engaging the valve Upon further movement of the head 24, .the slightly shorter arm 32 comes in contact with the latch memberV 6l and releases the projection 69 from the projection 74. This enables the spring 55 to swing the lever 45 into its initial position, whereby the rod 45 is moved to cause the ñnger 44 to operate the valve stem 42 which in turn causes the valve member to close the inlet port 3l and open the exhaust port 35. The sudden ex haust of the fluid pressure medium from the cyl inder enables the springs 34, which are relatively stem 42 which is mounted on one end of a slid strong, to return the ram member 2i and its asso able rod 45 extending through one of the tubuu ciated parts to their forward position. lar guides 2l; a lever 46 pivoted at 4l and hav It will be understood that, while an illustrative ing the other end of the rod 45 connected thereto 30 embodiment of a device or devices for con-trolling at 45; and a spring operated device connected to the mechanical operation of .the ram has been the other end of the lever 45. The spring oper described, other devices suitable for accomplish ated device may comprise a tubular collar 55 piv ing this purpose may be utilized and that the otally connected to the lever 45 at 5I; a slidable present invention is not intended to be limited to bai- or rod 52 extending through the collar 5l! .. the illustrative control means just described. and limited for sliding movement with respect The present invention, as illustrated in the thereto by a ñange 54; and a cylindrical helical embodiment thereof, is morey particularly con spring 55 which is telescoped about the rod 52 cerned with a method and apparatus for detect and is compressed between a ñange 56 adjacent ing when the reciprocating movement of the stud one end of the rod 52 and the collar 55. The end 40 or bolt I4 and its associated parts is interrupted, of the rod 52 adjacent the ilange 55 has one end is slowed down in some manner or ceases, due to of a. tension 'spring 5l attached thereto and the failure of the gun to fire and recoil. These de other end of the spring is secured to a suitable tecting means then control the operation of the fixed point at 59. 'I'he other end of the rod 52 solenoid 65 which permits mechanical action of is provided with a projection, tooth, or dog 5G the ram and its control devices. These detecting adapted to be engaged by a projection 5I on a means may be structurally associated with the latching lever 52 pivotally mounted at >64. reciprocating bolt I4 to detect lack of motion When the projections 60 and 6l are in engage thereof by a current pulsing means such as an ment, the spring 55 is compressively loaded and interruptor or alternator operated, actuated, bears against the collar 50 to swing the lever 45 50 driven or otherwise associated with the recipro in a direction to slide the rod 45 into a position cating parts of the gun charging mechanism. whereby the finger 44 holds the valve stem 42 In Figure 2 of the drawings a current inter to cause the valve member 4G to close the inlet rup-ter is illustrated as a'ñxed elongated com port 37. The projections C55 and 5I may be un mutator bar or frame 15 on which is mounted a latched by a solenoid 65 or other suitable device series of alternately arranged electrical conduct to be actuated when movement of the ram is de ing members 76 and non-conducting members 'Il'. sired. When the projections 54 and Si are un A slidable frame 'I5 is mounted on the guide rods latched, the spring 55 expands, and the rod 52 or tubes 21 and is attached to the stud I4 for slides within the collar 5E! to a position lwhere movement therewith. The frame 'I9 carries a the flange 54 abuts the collar 55 and the spring 60 brush or Wiper 85 for alternately contacting the 55 has no effect on the lever 45. The spring 5l members 'I6 and 'VI while reciprocating with re then pulls the rod 52 to 'swing the lever 45 into spect thereto. The conducting members 16 and the position, indicated by the broken line (de noting- the longitudinal axis of the lever), and the brush 89 are operatively connected in an elec trical circuit about to be described. The mem 65 the lever moves the rod 45 to enable the linger bers 75 and 'Il preferably are of >substantially 44 to release the valve stem 42. Movement of equal eiîective length whereby the period of flow the rod 45 may be further assisted by a spring of current and the period of interruption of cur 66 attached to the end thereof or to the finger rent are of a substantially equal duration of time. 44. Preferably, the lever 46 is latched in this position by a latch member 5l carried by the 70 Any suitable number of elements,> members or contacts 'I6 and 'I'I may be provided. Instead of lever and having a projection 69 adapted to en using a fixed interrupter bar l5, as illustrated, it gage a ñxed litch projection l0. will be understood that the stud I4 could carry i When the stem 42 is released, the pressure of any suitable linkage for driving a rotatable in the pressure medium moves the valve member 4I) away from the seat 36 and the pressure rne 75 terrupter, commutator or alternator adapted'to aaoacas 8 be contacted by a stationary brush, Without de parting from the scope of the invention. Referring to Figure 3 of the drawings, thereA is -is in a “firing” position. The pole |.0| is elec shown a wiring diagram of a preferred electrical detecting and operating circuit or “brainf’ This .circuit is illustrated as a modiñed bridge type cir lare electrically connected to each other by a trically connected to the current supply line 92 by a Wire |09, and the terminals |04 and |06 wire i I0 and .to a, wire ||| through which cur. rent is adapted to pass when the switch 8B is in cuit, and will be described in Ydetail hereinafter. The circuit shown is particularly adapted for ma chine guns installed in airplanes, tanks or other either of its closed positions. „ and the various circuits v may be respectively relay 9.6 and normally is in position to close the firing circuit, as shown in Figure 3. The switch |25 when in this position, is adapted to permit The wire ||| is connected to a wire ||2 which is connected to one terminal of the thermostat craft wherein the gun may be operated locally or 10 ically responsive switch QI. The other terminal of the switch 9| is connected to one terminal of from a remote location. Generally, to accom the heater 90, which has its other terminal plish this the electrical devices of the circuitare grounded at Hd. The wire ||| is also connected arranged in three groups designated as the con to a wire ||5 which is connected to one terminal trol panel, the relay panel and the gun charger. The control panel has mounted thereon, a pilot 15 of the manually operable switch 81 and the other terminal cf the switch 8'! is connected by a light 85 adapted to vbe illuminated when the gun wire || 6 to one terminal of the pressure medium charger ram |S is operating; a switch `iîii having valve controlling solenoid 05, which has its other a “safety,” “off” and “ñring” position; and a terminal grounded at ||'|. The wire ||| also is switch 81 for effecting operation of -the gun charger at the will of the gunner or operator. A 20 connected to one terminal of the pilot light 85 by a wire ||9 and the other terminal of the pilot firing or trigger switch 39 is operatively `asso light 85 is connected to one terminal of the pilot ciated with the control panel, and may be located light operating switch 99 by a wire |20. The adjacent the gun or at a remote location where other terminal of the switch 99 is grounded at 12|. the gunner Aor operator may .centrally control the The pole |02 of the switch 86 is adapted to ñríng of vone or more machine guns. An elec Contact the switch terminals |05 and |01. In the~ trical heater 90 may be provided for the vessel circuit shown, the terminal |05 is not electrically i6 containing the pressure medium to prevent ,the connected because it is superiiuous, but the termi pressure from dropping below a desired minimum nal |01 is connected to the ñring circuit by a wire when the vessel is exposed lto Very low tempera tures, such .as may be encountered at high .alti 30 |22, as described hereafter. The pole |02 is con nected to one terminal of the firing or trigger tudes. The heater circuit may lead to the con switch 89 by a wire §24 and the other terminal of trol panel and preferably has a thermostat EH the switch 80 is connected to the supply line 62, therein which is operative in response to ltem whereby when the switch 86 is in iiring position peratures at which the heater 90 is desired to operate. A source of direct current is supplied by and the trigger switch ââ is closed, current ñows through the iiring circuit by way of the wire |22. a line 02, conventionally indicated as having a positive polarity. The negative pole of the source The ñring circuit includes a single pole double of current (not shown) may be suitably grounded throw switch |25 which is associated with the grounded at desired points to complete the Apaths through which current may ilow. The relay panel has mounted thereon three resistance elements 94A, 94B and 04C, the pur pose of which will be described hereinafter; a relay 95 adapted to be operated by continuous current and unaffected by rapidly interrupted current to pass from the wire |22 to a wire |26 connected to one terminal of the iiring pin sole noid H50, which has its other terminal grounded ' at l |27. When the relay 96 is operated, the switch |25 is adapted to be moved into its other position to permit current to ñow from the wire |22 to a wire |29 connected to the wire IIB leading to the pressure medium valve controlling solenoid 65. current; and a second relay Qûvadapted to be op erated by the relay 95 to close a `circuit adapted to supply current to the pressure medium Valve controlling solenoid E5. Ii desired the relay 96 50 A preferred method for supplying interrupted current to the relay during the normal operation may be omitted by providing the `relay 95 with of the gun and continuous current during stop contacts for closing the solenoid circuit. page or slowing’down of the gun charging mech The gun charger has associated therewith-«the anism may comprise connecting the relay into a current interrupter, indicated by the interrupter bar l5 and the brush 80; a resistance element 04D; a switch 97 for cuttingrout ,the detecting cir cuit when the ram i9 is operated; and a switch 99 movable into a position for closing the >pilot circuit including 4a current supply and an inter ruptor, in such a manner, that it is normally light circuit responsive to the operation >of the poles |0| and |02; a pair or" contacts or terminals tinuous current when the charging mechanism has stopped for a given period. A preferred circuit for carrying out this method of `detecting the lack of reciprocating `movement of the gun charging mechanism and for initiating operation of the gun charging ram will'now be de scribed in detail. IThis circuit is illustrated in Figure 3 and is illustrated in simplified form in Figures 4, 5 and 6. Generally, this circuit com prises the current interrupter 15; the brush 80 moved by the reciprocating parts of the gun charging mechanism; the resistance elements |04 and |05 adapted to beengaged'by. the poles 95A, 94B, 513C and StD; the relay 05; and the cut ram. The solenoid 65 for controlling the pressure medium valve 35 also may be associated with the gun charger and a circuit may pass through the gun charger housing for energizing a ñring pin solenoid |00 associated with the iiring mechanism of the gun. The electrical circuits, illustrated in Figure »3, will now be described. The switch 66 «is of the double pole double Ithrow type having a `center “01T” position. The switch comprises apairof subject to a rapidly interrupted current by which it is not aiîected, and that it is subject to a con out switch 91 adapted to render .the circuit in eiîective during operation of the ram -|55. Elec trical energy is adapted to besupplied tothe cir minals |06 and |01 adapted tofbe engaged by the poles |0| and |02, respectively, when the switch 75 cuit from the >source of direct Vcurrent _92 con |0| `and |02, respectively, when the switch is 1in a “safety” position; and a >pair of 4contacts or ter 2,409,623 9 io nected through the switch 86 and the firing or lay of the foregoing character is preferred, other , trigger switch 89, when in firing position, to the devices having similar electrical characteristics wire |22 which in turn is connected to a wire |30. may be employed. The relay .05 may be provided with a single pole, single throw switch |39 (Figure 3) which normal-` ly is in open position and is adapted to be closed by the operation of the relay 95 to close a circuit leading from wire |22 through the coil of the re-lay 9S to the grounding connection at |40. Thus, when the switch |39 is closed, current is supplied to the relay 96 to operate the switch |25 which closes the‘pressure medium valve controlling sole noid circuit to effect operation of the ram |9. The path of the current which may pass through the circuit is completed by grounding the brush 80 at I3! and the resistance element 94C at |32 (Figure 3) or by electrically connecting the brush 80 by a wire |34 to the grounding connection at |32 (Figures 4, 5 and 6) . In the detecting circuit the resistance elements 94A and 04B each have one terminal connected to the current supply wire |30. These elements have substantially the same electrical resistance, to provide an electrically balanced circuit under certain conditions of operation, which will be de-, scribed hereafter. The other terminal of the ele ment 94A is connected to one terminal of the element QQD by a wire |35 and the other termi nal of the element 94D is connected to a wire |36 which is connected to all of the conducting 20 members 76 of the interrupter l5. The other end of the element 94B is connected to one terminal of the element 94C which has its other terminal grounded at |32. The elements 913C and 94D have substantially the same electrical resistance for the reasons described hereafter. In effect, and as illustrated more particularly in Figures 4, 5 and 6, the elements B and C and the elements A and D, respectively, are connected in series. The respective pairs of elements pro vide, in effect, parallel circuits leading from the wire |30 to the grounding connections at |32. The relay 95 is connected across these “parallel circuits” by connecting one terminal of the relay 95 to the wire |35 or the connection between the elements 06A and 04D and connecting the other terminal of the relay 05 to the connection be tween the elements B and C, indicated at |37. The relay 95, as previously explained, is of the type which is adapted to be operated by continu ous current flowing in either direction, for a pre determined period but is not affected by current which alternates its direction of flow or is inter rupted at a frequency higher than a predeter 4.. .i mined frequency. Such a relay may be of the so called “time delay” type in which a heavy copper The relay 95, when connected in the circuit just described, is normally supplied with alternating or rapidly reversing current while the gun charg ing mechanism is reciprocating or is operating to load and fire the gun at its normal speed. The al ternation of the direction of flow of the current is accomplished by the circuit, shown in Figures 3, 4, 5 and 6, and the interrupter 'l5 or other suit able device therein in the following manner. -Y When the brush 80 contacts any one of the cur rent conducting elements 'l5 (Figure 4), current from the wire |30 divides and flows through the resistance elements 04B and 94C to the grounding connection at |32, as indicated by the arrows a. The divided portion of the current ñows through the resistance element 94A, the wire |35, the switch 91 (normally closed), the wire |36, oneV of the conducting elements 10, brush 80, and wire |34 to the grounding connection as indicated by the arrows b. The resistance to the flow of cur rent in the path of the arrows a -will be greater than the resistance to the flow of current in the path of the arrows b, whereby a portion of the current in path a will divide out at |37 and pass through the relay 95 in the direction indicated by arrow c. It will be understood that the resistance» characteristics of the relay coil are such that they will not impede the ñow of current in direc tion c. , When the brush 80 is moved out of contact with any of the conducting elements 'I6 and con tacts any one of the non-conducting` elements Tl or is in a position between the contacts 16 (Fig ure 5), current flows through the circuit as fol-_ lows. The current divides at'the wire |30 and a portion thereof flows through the resistance ele ring encircles the core of the relay. When cur rent starts to flow through the coil of such a relay, in either direction, a countervoltage is in 50 ments 04B and 36C to the grounding connection` duced by the short-circuiting copper ring, re~ |32 as indicated by the arrows a. The other por-VV tarding the build-up of magnetic flux and there tion of the current flows through the resistance fore retarding the operation of the relay. When element 94a as, indicated by the arrows b and the current has established itself, however,'the through the coil of the relay 95 to |31 as, indie copper short-circuiting ring has no effect and the cated by the arrow d, because the circuit leading relay operates in the normal manner. The only effect 0f this ring is to delay the relay operation for a fraction of a second. Thus when alternat ing current of a suniciently high frequency is ap plied, the relay is not affected and will not operate because the direction of the current is being re~ versed so rapidly that the magnetic flux does not through the interrupter ‘l5 is broken. The direction d, as will be noted, is opposite to the direction c, and the direction in which the>> current flows is rapidly alternated by the rapid movement of the brush/80 from a circuit closing to circuit opening position. Thus, if a sufficient number of conducting elements 16 and alternate have an opportunity to build up. ' ly arranged non-conducting elements 'Vl are pro# It has been found that a relay, known as a vided in the interrupter and the interrupter brush direct current, series, slow releasing type relay 65 30 is reciprocated at a rate of 400 to 1000 strokes' may be utilized. Preferably this relay has an 0D per minute the direction of the current will be erating time of about .004 to .25 second and a alternately reversed at a rate at which the relay releasing time of about .020 to .350,second. Such S5 will not be operated. For example, if the frea relay is illustrated on page 8 of Catalogue _quency of current reversal is of a magnitude at 4071-B, published February 1940, by American 70 `which current flows in either direction for a pe Automatic Electric Sales Company, Chicago, Illi riod of time, shorter than the time required by nois. Since such relays are generally known and the relay to build up magnetic iiux, the, relay will not be aifected. The relay will be operated only are commercially available, a detailed description when the brush 80 stops moving or slows down of the construction thereof is not believed to be to an extent where the frequency of the currentnecessary. It will be understood, that while a re » 2,409,623 ll reversals is relatively low. The latter condition would indicate that the gun is not firing proper ly. In the event the brush stops while in contact with a conducting element l5, direct current will flow through the relay coil in direction c (Figure 4) . If the brush stops while out of contact with 12 Once the gun commences ñring and the trigger switch 89 is held in closed position by the gunner or operator, the gun continues to nre and the charging mechanism goes through its cycle of op~ eration, namely, feeding, ñring and ejecting cartridges. During the operation ci the charging mechanism, the current interrupter l5 is operated and the direct current supplied to the detecting an element 16, direct current will flow through the relay coil in direction d (Figure 5). devices is converted into substantially rapidly in The operation of the cut-out switch al is il lustrated in Figure 6. In the event the detecting 10 terrupted or alternating current with respect to the relay 95. While the current is thus alter devices initiate operation of the ram i 9, the ram nated or interrupted, the continuous current re ming head 24 or a member carried by the head sponsive relay 95 is unaffected and does not op may mechanically engage the switch 9i upon ini erate. However, if normal movement of the re tial movement of the ramrning head 2li and .move it out of its normal position shown in Figures ‘l 15 ciprocating parts of the gun charging mechanism should cease, the current through the relay be and 5 and into the position shown in Figure 6, comes sufficiently continuous to cause actuation whereupon the kswitch 97 opens the connection of the relay. Within a fraction of a second, the between the wires |35 and |35 and connects the relay 95 is operated to close the switch |39, wire |36 to the grounding point lâ I . whereby current ñows through the auxiliary re If the brush 80 is out of contact with a con lay 96 to operate the switch §25. The switch |25 ducting element 'i6 of the interrupter, the current _cuts out the source of current supplied to .the will divide at |30 and a portion will now through ñring pin solenoid Iüil and connects this source the resistance elements 94B and MC to the of current to the pressure medium valve con grounding connection |32 and the other portion of the current will îlow through the resistance ele 25 trolling solenoid 65. The solenoid 65 is immediately effective to re ment 94A, the wire |35, the resistance element lease the latch and lever mechanism, illustrated 94D, the wire |35` and the switch 97 to the in Figure 2, which in turn operates the Valve to grounding point illl . Since the resistance of ele admit pressure medium to the cylinder 2D of the ment 94A is equal to element 94B, and the resist ram. The ram is then operated to mechanically ance of element 94C is equal to element MD, the move the gun charging mechanism through its sum of the resistance of elements 94A and 94D is operating cycle to put the gun in action again. equal to the sum of the resistance of elements MB As the ram is operated, the cut-out switch 91 is and 94C. Therefore, the same proportion of cur moved into the position in which it prevents the rents flows in paths a and b, whereby the two flow of current through the detecting relay 95 paths-are balanced and no current flows through (Figure 6). Also, the pilot switch 9E) is closed so the relay 95. Thus when this condition prevails, that current ,flows through Vthe pilot light which the relay is insensitive and is not operated. The indicates to the gunner that the automatic gun switch Sl is designed to return by itself or to be charger is in operation. When the ram returns returned by the ramming head to its initial or normal inactivate position when the ram is 40 to its normal inactive position and the gun is restored to normal iiring the pilot switch S9 and moved into its normal or at rest position, as indi the cut-out switch Ell return to their initial po cated in Figure 2. sitions under the iniluence of suitable resilient In the event the ram is operated to move the means (not shown). As the gun resumes :firing cut-out switch 9T out of its normal position while the solenoids of the relays 95 and 95 become de the brush contacts one of the conducting ele energized to permit the switches |39 and |25 to ments 16, the foregoing result is accomplished in return to their initial positions under the >ini-lu substantially the same manner. The only difier ence of resilient means usually associated with ence now is that the current in the path b may relays of the type employed. ñow to either of the grounding. connections l32 In Figures '7, 8 and 9 a modified circuit is illus and lêl to complete the circuit. The circuits 50 trated, for interrupting the current for the de indicated by the paths a and b then are again tecting mechanism by alternating the direction balanced and no current is supplied to the relay thereof. The interrupter 15 comprises a series of 95. conducting elements or contacts "I6 and 16', a1 In operation, the gun charger l2 is attached to ternately arranged and spaced apart a short dis either side of the machine gun housing H, the tance by insulation, if desired. The contacts 16 pressure medium vessel |65 .is connected to valve are connected by a wire M5 to one terminal of 35 by the hose |71 .and the electrical circuits are the source of direct current indicated at |30, and connected to a source of electric energy, while the contacts ‘I6’ are ‘connected by a wire |46 and the main switch 86 is in its “oiî” position. When the switch is in this position, accidental closing 60 a resistance element IMC to the other terminal of the source of current indicated at |32. A slider the manually operable charging switch 'B1 or the or brush 8B rides upon a conducting bar or slide trigger switch 89 will not elîect operation of the 33 connected by a wire |41 'to one terminal of the gun charger or firing of the gun. After the gun relay 95. A resistance element l 94A has one ter and the gun charger is set up for action, either in the ñeld, in an airplane or other craft, the 65 minal connected at |33 to the source of current and has its other terminal connected at |31 to switch 85 is placed in its “safety” position. This one terminal of a resistance element |94B, which enables the gun to be charged by closing the Inan has its other terminal connected at |32 to the ually operable charging switch 8l, but accidental other pole of the source of current. The other closing of the trigger switch 89 will not ñre the terminal of the relay is connected at> |31. gun. Shortly prior to the time it is desired to The relay S5 operates only in response to direct rire the gun, the switch 8l is closed to charge or continuous current of sufficient duration in the gun and the switch 85 is placed in its “ñring” either direction and the interrupter 15, in con position, whereby the gun may be ñred by clos junction with the circuit as shown, is adapted to ing the trigger or firing switch 39 to energize the effect a rapid reversal of the direct current sup firing pin solenoid |90. 13 2,409,623 plied while the gun is iiring and the brush 80 is being reciprocated. The direction of the current through the relay is changed as follows. When the brush 8H contacts one of the elements '16, as shown in Figure 7, a portion of the cur- ' 14 While my invention resides in certain prin ciples of construction and operation which have been illustrated and described in connection with the accompanying drawings, it will be apparent to those skilled in the art that the invention may be embodied in other forms of construction and modes of operation without departing in any rent iiows through resistance elements IMA and |94B, as indicated by arrows a. Another portion of the current flows through wire |45, contact 76, manner from the spirit and scope of the inven brush 80, bar 83, and wire |41 to -the relay Q5 in „ tion, and I therefore do not wish to be strictly the direction as indicated by arrows b. 10 limited to the disclosure, but rather to the scope When the brush 8|) contacts one of the ele of the appended claims. ments 16’ as shown in Figure 8, the current ñows I claim: through resistance element |94A and a portion of 1. In a gun charger for a machine gun having the current ñows through resistance element a reciprocating membenthe combination with I94B, as indicated by arrows a. The current di 15 said reciprocating member of a normally inactive vides at |31 and a portion thereof flows through recharging mechanism for operating the recipro the relay 95, wire |47, bar 83, brush 80, contact 16', wire |46 and resistance element |940 to the pole |32 of the source of current as indicated by cating member, an electrical control device con structed and arranged to be actuated by a cur rent pulse of a predetermined minimum time in arrows a'. 20 terval for rendering said recharging mechanism In the event the gun ceases firing and the brush operative, an energizing circuit for said control stops in an intermediate position where it con device, and currentpulsing means in said circuit tacts both an element 'i6 and 16', as shown in adapted to be driven by said reciprocating mem Figure 9, a portion of the current ñows through ber, said pulsing means being constructed and resistance elements |94A and | 94B. Another por 25 arranged to successively energize said control de tion of the current ilows through wire |45 to the vice for intervals less than said minimum time interrupter 'l5 where it divides and a portion flows interval during the normal operation of said re through wire |41 and the relay 95 in the direc ciprocating member and to energize said control tion of arrow b and the other portion of the di device for said time interval for rendering said vided current ñows through the wire |46 and 30 recharging mechanism operative upon failure of resistance element |940 to the current connec normal operation of said reciprocating member. tion |32, as indicated by the arrow b’. The re 2. `In the combination of claim 1, means op sistance element | 94C prevents a direct short cir erated by said recharging mechanism upon move cuit and preferably has a resistance slightly ment thereof for'rendering said pulsing means greater than the resistance element |94B so that 35 ineffective to energize said control device. the circuit is unbalanced and current flows 3. In the combination of claim 1, said current through the relay 95. pulsing means including a rcommutator, and a During the normal firing of the gun the direc brush adapted to be connected to said recipro tion of the current is alternately reversed as cating member for cooperation with said com noted in connection with Figures 7 and 8. If the 40 mutator. gun should cease ñring and the brush stops in 4. In the combination of claim 1, said current any one of the positions shown in Figures 7, 8 pulsing means including a commutator, a brush and 9, current will flow continuously in the direc adapted to be connected to said reciprocating tion indicated. member for cooperation with said commutator, From the foregoing description it will be seen and switch means constructed and arranged for that the present invention provides an improved rendering said commutator ineffective when said gun charger and improved method of operation.v recharging mechanism is operated. The gun charger detecting devices are adapted 5. In the combination of claim 1, said energiz for machine guns having a relatively high firing ing circuit comprising two portions, vsaid control speed and quickly detect a failure of operation 50 device being connected across said portions, said and return the gun to tiring operation in a mini current pulsing means including a current in mum period of time. Machine guns equipped terrupter actuated by said reciprocating member with gun chargers in accordance with the inven connected in one of said circuit portions. tion are adapted to be put in action again in a 6. In the combination of claim l, said energiz split second vand the eifective iiring of the gun 55 ing circuit comprising a bridge having four re is not materially decreased even under adverse sistance elements, the total resistance in a pair conditions, whereby the gunner is not endangered by being subjected to enemy fire without being of adjacent elements being equal to the total re sistance in the other pair of adjacent elements, able to return ñre. The parts of the gun charger said control device being connected across said are rugged in construction and are adapted to 60 pairs of elements and said pulsing means includ withstand any rough usage to which they may be subjected. W'hile my invention has been described in con nection with a gun charger for automatic ma ing a current interrupter adapted to be actuated by said reciprocating member for interrupting said bridge at a common junction of said pairs of elements, whereby said control device is ener chine guns, it will be understood that the prin 65 gized. ciples of my invention may be applied to other 7. In a gun charger for a machine gun having mechanisms where it is desired to detect the a reciprocating bolt, the combination with said slowing down or stopping of any mass or parts bolt of a normally inactive ram for operating the normally intended to be in motion. For example, bolt, an electrical control device including a relay a detecting device embodying my invention may 70 constructed and arranged to be actuated by a be utilized in connection with electrical, pneu current pulse of a predetermined minimum time matic or hydraulic motors, internal combustion interval for rendering said ram operative, an or steam engines, or other mechanisms or de vices having parts moving in a circular, linear or curvilinear path. energizing circuit for said relay, and current puls ing means in said circuit adapted to be driven 75 by said bolt, said pulsing means being constructed 2,409,623 15 and arranged to successively energize said relay for intervals less than said minimum timeV inten` val during the normal operation of said bolt andv to energize said relay for said time interval for rendering said -fam operative upon failure of nor mal operation of said bolt. 8. In a gun charger for a machine gun having a reciprocating bolt, the combination with said 16 means in said circuit adapted to be driven by said bolt,~said pulsing means being constructed and arranged to successively energize said relay for intervals less than said minimum time inter val during the normal operation of said bolt and to energize said relay for said time interval for rendering said ram operative upon failure of nor mal operation of said bolt, and a switch in said circuit constructed and arranged to be operated bolt of a normally inactive ram for operating the bolt, an electrical control device including a relay 10 by said ram upon initial movement thereof for rendering said pulsing means ineffective to ener constructed and arranged to be actuated by a gize said relay during operation of said ram. current pulse of a predetermined minimum time interval for rendering said ram operative, an energizing circuit for said relay, current pulsing HARRY C. GRANT, JR.