US2767615A - Reloader and magnetic brake for automatic machine gun - Google Patents

Description

l'()frt- 23', 1956 A. HARDY y 'RELOADER ANnfMAgNETIc BRAKE FOR AUTOMATIC 1MM-:mmaY GUN Filed Feb'. 1.4. 1952 2 E Shee tS-Shet 2 with facility and speed.

United States Patent() RELOADER AND MAGNETIC BRAKE Fok AUTOMATIC MACHINE GUN l Albert L. Hardy,

United States of tary of the Army Schenectady, N. Y., assignor to the America as represented by the Secre- The present invention relates to an electric charger and to a magnetic brake for the operating motor of an electric charger or reloader for a machine gun.

Generally, guns of the type which are provided with an electric reloader are recoil operated so that when the gun is tired, recoil of the barrel unlocks the breech and drives back the bolt. In moving back, the bolt ejects a spent cartridge, withdraws the firing pin, actuates the belt feed mechanism to pull a cartridge toward the center of the belt feedway, and cocks the bolt mechanism so that the next round can be fired. Throughout recoil of the bolt a drivespring is being compressed, and if the sear has been depressed to free the bolt mechanism for counter` recoil, either mechanically or electrically, the .bolt assembly rebounds from the buifer mechanism and commences another firing cycle, and in so doing strips the live cartridge from its link in position on the belt feedway and chambers it. The final forward movement of the bolt pushes the tiring pin into and tire the cartridge.

Machine guns of the before-mentioned type haveused manual means for reloading and charging, when a new ammunition belt has been fed into the gun, or when a defective shell or dud has entered the chamber to destroy the recoil actuation of the gun. However, mechanical actuation has been found wanting in several important particulars; namely time and effort required to overcome the strength of the drive spring, and more important, inaccessibility of the charger as, for example, in

. guns mounted in'the wings of airplanes.

Remotely controlled electric chargers, to replace the mechanical means, accomplish charging and reloading The charger is mounted within the belt feed tube of a gun and is retained in place by means engaging a hole in the cover of the gun. The charger motor is a high speed, series wound motor with a double eld winding for rotating the armature in either clockwise or counterclockwise direction.4 The shaft of the motor is provided with a driving connection to a lead screw which in turn is connected to the bolt and to the feed tube, and the circuit which includes the fields of the motor is arranged so that closing of the loading switch energizes the power stroke field to rotate the motor and lead screw in a clockwise direction to withdraw the bolt to cock the gun, and to actuate the belt feedway by means of a rack connection with the feed tube to commence the placement of a live cartridge in the chamber. As the bolt approaches full recoil position the bolt rides down a tell-tale which is connected to a tell-tale switch in the motor circuit to de-energize the power stroke field and to energize the return stroke eld to rotate the motor in counterclockwise direction. The switching to counterclockwise rotation from clockwise rotation, or vice versa, from clockwise to counterclockwise rotation if the need arises, should be effected instantaneously to prevent malfunctioning of the charger. Functioning tests of machine guns supplied with electric charges have disclosed failuresA of theA electric charger assemblies aggravated by position to strike the primer rice transmitting forces resulting from motor armature inertia to the armature shaft and associated motor springs and parts. Additinally, the tendency of the charger mo'tor to overrun and to force the lead screw drive assembly against the motor armature shaft has caused failures at weak points of the lead screw and at the motor housing bearing supports.

it is accordingly an object of this invention to provide means combined with the electric charger to dissipate armature energy of the reversing motor more positively and to prevent excess forces from being transmitted to the lead screw and to motor components.

it is also an object of this invention to provide a magnetic brake having a solenoid coil in series with the power stroke and return stroke fields of the charger motor, constructed and arranged to provide positive and immediate stopping of the armature when the motor is reversed.

lt is a further object of this invention to provide a magnetic brake for the reversing motor of the charger mechanically arranged to allow the use of an air gap which may be as little as .005 in the non-energized position with a resulting high pull for the brake size.

It is also a further object of this invention to provide a magnetic brake having a solenoid coil of heavy, low resistance wire arranged in series with the power stroke field and return stroke eldv of the charger motor to permit rapid braking action, with minimum delay by back E. M. F. current, due to residual field in the motor during stopping. i

With these and other objects in view, which will become apparent as the following specification develops, reference is made to the accompanying drawing forming a part of the specification and wherein:

Figure 1 is vertical longitudinal section with some parts in elevation of an electric charger and pertinent parts, providedwith the magnetic brake of this invention, and mounted in the cover and receiver of the machine gun.

' Figure 2 `is an enlarged vertical longitudinal section of Y the rear portion of the electric charger and mechanical brake.

Y Figure V2a isa continuation of the section of Figure 2.

Figure 3 is a horizontal longitudinal section with follower in plan of the forward portion of the charger.

Figure 4 is an isometric view of the feed tube including the helical groove.

Figure S is a View of a disc which rotates with the motor shaft and which cooperates with the magnetic brake.

Figure 6 is a schematic diagram of the loading and power circuits to the charger motor and brake, and the firing circuit'.

Referring to the drawing wherein are illustrated those parts of the gun which are most pertinent to the operation of the electric charger, and which are important from the standpoint of following through a typical loading cycle, reference character 1 represents the receiver of a machine gun, and 2 is a cover for inclosing the top of the receiver. The front end of cover 2 is attached to the receiver by a hinge pin 3 which engages a-hooked projection 4 on top of the receiver. Means (not shown) are also pivoted to latch the cover in place and maintain it closed.

A belt feed tube 5 (see Figs. 2 and 4) is mounted in the toppart of the cover and is held in place at its forward end by an inwardly turned tiange 5a which engages a shoulder 6a of a belt feed tube lock 6, upon which it is mounted for oscillation as 7, and at its rear end by a bearing 8 secured to the cover at 9, bearings 7 and 8 permitting oscillation of the tube 5 by the electrical charger and associated parts as subsequently to be described. The belt feed tube is provided with a plurality of peripheral longitudinal grooves lt), which act as gear teeth to engage a belt feed rack 11 forming a part of the feed assembly for automatically placing a live cartridge 12 into position to be chambered in response to rotation of the feed tube. The details of the belt feed assembly are not pertinent to an understanding of this invention, therefore they have notl been illustrated or described yin detail.

The electric charger yisassembled inside of the belt feed tube as seen in Figure l, and comprises a motor assembly 13, a motor mount and bearing assembly 14, friction drive and drive spring assembly 15, a lead screw and nut assembly 16, drive bushing assembly 17, follower assembly 18, and magnetic brake 19.

rl`he electric charger will now be described in detail in connection with Figures 2, 2g, 3, 4 and 5, and the circuit diagram of Figure 6.` The motor mount is provided with 2 bayonet vslots 20 that engage pins 21 located in the rear of the cover, and a A'spring biased motor mount locking plunger 22 adaptedto be'received in a hole 23 in the cover top. In assembling the charger in the cover, the motor mount is given a clockwise twist and slots engage pin 21, at the same time plunger 22 snaps into place within hole 23, to securely hold the charger in the cover. The mount is also provided with a forward extending reduced cylindrical portion 24 and an axial bore 25 enlarging into a rearwardly disposed counterbore 25a. Within bore 25 is 'received for rotation an elongated forwardly extending friction drive tube 26. The rearward end of drive tube 26 extends into couuterbore 25a and is provided at its rear end with an outwardly directed ange 27. Also received in counterbore 245 is a friction drive ball thrust bearing 28 comprising o uter race 29 engaging the side wall of counterbore 25a and inner race 3Q which engages a short cam sleeve 31 secured to drive tube 26, sleeve 31 having an enlarged rear end 32 abutting flange 27 of tube 26 on one end and the rear face of inner race at its forward end. The usual roller bearing 30a is received between the inner and outer races.. The enlarged end 32 of sleeve 31 is provided with a beveled rearV cam face 33 for the purpose to be later described. A friction drive shaft 34 is freely received in drive tube 2 6 and is provided with a'forwardly extending reduced portion 35; Shaft portionV 35 forms with the inner wall of drive tube 26 an annular chamber 3,6 for a purpose to be later described.

The motor assembly 13 and magnetic brake 194` are fastened to the rear of the motor mount assembly as follows. A thin annular cylindrical spacing member 37 is disposed between the rear flat face ofthe motor. mount and the forward face ofthe` motor housing, with its outer peripheral surface engaging the rearA inner wall of the cover. Motor mountings screws (not shown) extend through axially alined` holes in the motor and, mount to secure the two members together. Received within the space encompassed byl spacer 37 is a fiat disc like cylindrical member 38 secured to the front face of the motor housing, and provided with diametrical opposed longitudinal bores 39 (one shown Fig. 2) for receiving compression springs 40. Inwardly of bores 39, in member 3Sris formed an annular groove or recess 41 in which is disposed a winding 42, combining with member 38 to form a solenoid housing of the magnetic brake. The solenoid housing is centrallyr apertured at 43 to provide a bore into which extends rotating shaft 44 of the motor. Springs 4t) in bores 39 are connected at one end 45 to the motor housing and the other end 46 to a disc-shaped substantially fiat armature 47 having annular face 48 which cooperates with an adjacent flat face 49 of the solenoid housing. Springs 40 normally bias armature 47 out of engagement with solenoid 38 when the solenoid winding 42 is deenergized, such that the adjacent faces are separated by an air gap of approximately .005. As can be seen in Figures l', 2 and 6, this air gap is readily achieved with the parts assembled as described above without the need for line machining, adjustments or shimming of the associated parts. Additionally this arrangement results in a relatively high pull for a brake of this size. Friction drive shaft 34 is provided with a splined axial bore 34a at its rear end which makes a splined connection as at 48a with splined motor shaft 4d to conjointly rotate therewith when the motor fields are energized. A short sleeve 49a is iixedly secured to the outer periphery of the rear end of friction drive shaft 34, and ametallic brake disc 50 is keyed to sleeve 49a to rotate with the friction drive shaft within counterbore 25a. Nhen the brake solenoid 38 is deenergized to cause springs 4i) to press varmature t7 out of engagement therewith, armature 47 is in position to frictionally engage the rear face of brake disc Sil to thereby hold the motor against rotation.

Reduced forward portion 35 of friction drive shaft 34 loosely tits into hole 51 in the rear end of a forwardly extending elongated lead screw 52 which has a smaller diameter than friction drive shaft 34 so that an annular chamber 53 is formed between the lead screw and drive'tube 26 which is larger than chamber 36, between the drive tube and drive shaft, and substantially alined therewith. The'drive shaft is coupled to the drive tube and to the lead screw by an elongated clutch spring 54 which surroundsthe drive shaft and lead screw and is constructed 'so as to tightly grip the outer surface of the drive shaft for that'portion of spring S4 disposed in annular chamber" 36, and to likewise tightly grip the inner surface of drive tube for that portion of spring 54 disposed 1n 'annular Vchamber 53. A rigid connection is provided between the ylead screw and drive tube to insure that these twol elements rotate as a unit. This connection is formed by turning down the forward end of drive tube 26 to forni a flange 55. A block 56 is press tted in drive tube 26 to abut the iange 55, and is provided IwithV an axial hole 57 to screw threadedly receive the lead screw 52. A pin 53 extends transversely through block 56, lead screw S2 and drive tube 26 to secure these members together. It can readily be seen therefore that as the motor rotates drive shaft 34,- clutch spring 54 rotates drive tube l26 and lead screw S2. Lead screw 52 extends forwardly substantially to the forward end of the cover, and is reduced at its forward end to form a journal 59 which is received for rotation in a bearing 641- formed in belt feed tube lock 6.

' The rotation of lead screw 52 lis instrumental in forcing rearwardly the Adrive bushing assembly 17 for withdrawing the bolt, through the medium of the follower'assembly 1S. The follower assembly is mounted in the lead screw and is located within a motor mount and follower guidesleeve 61 which is secured at its rear end to reduced portion 24 of the motor mount, 'and at its forward end in al recess 62 in follower stop 63 which is secured in any convenient manner about the lead screw a short distance rearward of the forward end of the screw. Forward of follower stop 63 is disposed a rubber washer 64, which is engaged by a flanged enlargement 65 of the lead screw forwardly of washer 64, as the lead screw moves rearwardly in a manner and for a purpose to be subsequently described.

The follower assembly per se comprises a follower cover 66 which is rearwardly of, and abuts follower stop 63 when the follower assembly is .in forward position. A follower housing 677 which is formed as an elongated cylindrical sleeve slidingly engaging the inner wall of motor mount and follower guide sleeve 61, is fastened at its forward end to the follower cover and at its rear end to a follower bushing. 63 disposed about lead screw 52. A follower spring 69 isyreceived in the follower housing and extends between bushing 68 at the rear end and a follower nut 70 at the forward end, and about lead screw 52. Follower spring 6,95 maintains follower nut 70 .in position against the follower cover and reduces the shock of sudden stopping of the nutkwhen the follower assembly is stopped. The follower nut is threaded to travel forwardly and rearwardly upon the threads of the lead screw tothereby cause the follower assembly to also move in coordination therewith. rIhe follower -assembly is prevented from rotating `by horizontal projections 71 formed integrally with the follower housing and cover (see Fig. 3)the projections in turn riding in longitudinal slots 72 in the motor mount and follower guide sleeve 61.

The follower projections 71 engage the drive bushing assembly and p-ull it rearward as the lead screw S2 turns clockwise in follower nut 70. The drive bushing assembly comprises a drive spring sleeve 73 which slidingly engages the inner wall of belt feed tube and which has its forward end turned down to form a ange 74 which slides upon the motor mount and follower guide sleeve 61. Drive spring 75 surrounds the motor mount and follower guide sleeve with the forward end contained within the drive spring sleeve land abutting flange 74 thereof, The rear of the drive spring abuts the motor mount at the forward reduced portion 24. The drive bushing assembly comprmses the drive spring when the drive bushing assembly is pulled rearward on the power stroke. The drive spring provides the power for -driving the drive bushing assembly forward. A connection between the drive bushing assembly and bolt, as later to be described, also moves the bolt forward. Within the motor mount yand guide follower sleeve 61 and surrounding the lead screw is located fa relief ball bearing 76, at a location just forward of the point where the lead screw is joined to the friction drive assembly. The purpose of this bearing is to prevent the follower assembly from jamming and sticking against the friction drive assembly when the lead screw has rotated sufficiently to move the follower lassembly rearwardly. Bearing 76 comprises a flanged cup 77 disposed about the lead screw and having forwardly directed edge 78 engaging the periphery of the follower guide sleeve 61. Within cup 77 is located a forward race 79, rear race 80 and roller beatings 81 therebetween.

As previously explained the drive bushing assembly slides inthe belt feed tube. A stud 82 projects downward from the drive bushing and engages a socket 83 in the top of the bolt. A roller 84 on the stud rides in a track (not,V shown) formed by the sides of the cover to prevent the drive bushing assembly from turning in the cover. The stud 82 is provided with hardened cam surfaces 82a which contact spiral slot 84a (see Fig. 4) in the belt feed tube so that as the bolt moves forward the cam surface causes the belt feed tube to rotate about one half turn and to cause the belt feed gear teeth to move the belt feed rack ll'toward the side ofthe gun -into which ammunition is being fed. As the bolt assembly and drive assembly move rearward the belt feed tube rotates in the opposite direction and moves the feed rack inwardly to pull a cartridge to the center of the cartridge belt feed preparatory to chambering it. A sear assembly 200 is mounted in the bottom of the receiver and normally held upward by a sear spring 201. As the bolt moves rearwardly the searr engages a shoulder 202 on the bottom of the bolt and holds it in rearward position until the Sear is depressed.

The remaining parts in the receiver of the machine gun which cooperate with the electric charger and with the loading and firing circuit will now be described. Buffer housing 35 located at the rear of the receiver houses the buffer group (not shown in detail) for cushioning the recoil of the bolt assembly. A solenoid 86 fastened to the rear of the buffer housing, comprises (see Fig. 6) coil assembly 87, armature 88, solenoid arm 89 which is pivotally connected to armature 88, as at 90 and solenoid shield plate 91. Above the front end ofthe buffer housing is located a firing circuit closer switch 92 comprising a switch arm 93 pivotally connected as at 94 to a lower shoe 95. Lower shoe 95 and upper shoe 96 have a common pivotal connection 97 with the receiver, and disposed between adjacent faces of shoes 95 and 96 is a compression spring 98. As cam sleeve 31 and drive tube 26 are pushed rearwardly under the action of the lead screw, cam face 33 abuts upper shoe 96 and forces it to pivot counterclockwise against the action of spring 9S to depress lower shoe and move switch arm 93 out of engagement with contacts in the return circuit and into engagement with contacts in the firing circuit. (See Fig. 6*). The electrical charger is provided with contacts 99 which mate will corresponding contacts 100 on the' rear end of the buffer housing when the cover is closed.

Referring to Figure 6 the power circuit for the magnetic brake and charger motor, comprises source of power 101, connection to ground 102, and loading switch 103. From switch 103 the power circuit is connected by way of conduit 104 to a tell tale switch arm 105, and to power circuit Contact 106, via conduit 107 to the clockwise or power stroke eld 108 of the charger motor, then Via conduit 109, through armature 110 and by way of conduit 111 to one side of the magnetic brake coil 42 and then to ground.

The return circuit is traceable from loading switch 103 and tell tale switch arm 105 to return circuit contact 113, then through conduit 114 through upper contacts 115 of firing circuit closer switch 92, and through conduit 116 to counterclockwise or return stroke field 117 of the charger motor. From field 117 a conduit 118 connects with armature 110, wherefrom conduit 111 connects to brake coil 42 and then to ground.

The firing circuit is traceable from power source 101 through conduit 119 to lower contacts 120 of switch 92 which are engaged when shoes 95 and 96 depress switch arm 93, through conduit 121 to firing switch 122 and through the scar operating solenoid eld and then to ground.

As plainly seen in Figure linked to Sear arm 105a, has a forward flat surface lying adjacent to and disposed behind a tell tale arm 122:1. Sear arm 105:1 is forwardly stepped to form a first thicker portion 105b, and a second portion v105e thicker than portion 105b. Tell tale arm 122a is notched as at 1221; and thickened portions 105b and 105e extend thro-ugh notch 12217 so that the shoulder formed by thickened portion 1051 abuts the rear end of notch 12217 whereas the thickened portion 105C abuts the sear 200, which is pivotally connected to the receiver body and which is biased upwardly by a Sear spring 200:1. Rearwardly of the sear is also pivotally mounted a tell tale 124 which has a pin 124a extending horizontally therefrom to be received normally in the forward end of an 6 solenoid arm 89 is pivotally arcuate slot 127 in sear arm 105e. The tell tale has a.v

fixed connection with tell tale arm 122a so that as the tell tale is depressed by the rearward travel of the bolt tell tale arm 122e also moves rearwardly and takes with it a switch cam arm 125 which has a rear end joined to the tell tale arm and a forward end joined to switch arm 105,

such that depressing the tell tale breaks contact between switch arm 105 and contact 106 and makes connection between switch arm 105 and contact 113. Sear arm 105a is normally biased in a forward position by a spring which is connected at one end to the sear arm and at the other end to the tell tale arm. When the sear operating solenoid is energized Sear arm 105a is drawn rearwardly so that thickened portion 105C abuts and depresses sear 200 to release the bolt.

The operation of the electric charger and magnetic brake for a reloading cycle will now be described. Just prior to reloading, the bolt head is locked in the breech ring assembly. Details of the bolt and breech ring assemblies form no part of the present invention and have not been described in detail, however it suices to say' that buttress locking lugs on the breech ring assembly engage with mating lugs on the outer surface of the bolt head to lock the bolt head in forward position. The bolt head is swivelly mounted and may be turned for unlocking either by unlocking cam means which operates in conjunction with the recoil of the barrel, or by cam lugs on the sides of the shank of the bolt operative in which extends forwardly andl spiral grooves in the bolt head assembly. The latter cam means is operable in response to a pull or backward movement of the bolt assembly. A cartridge belt is placed in position on the belt feed rack. Firing switch 122 is kept open, the sear operating solenoid remains deenergized, the sear and tell tale are in their upward position, and switch arm 165 of the tell tale switch is engagement with contact 106. Loading switch 103 is now closed and current proceeds fro-m power source 101 through switch 163, conduit iM, contacts MP and 106, conduit 107 to energize power stroke iield ill to tend to turn the charger motor in a clockwise direction. Simultaneously field 42 of magnetic brake 15, which is connected in series with the charger' motor elds, is also energized to attract armature 47 which moves rearwardly against the bias of spring 4h to disengage brake disc 5t). The charger motor is now free to turn clockwise, simultaneously turning friction drive shaft 34, and also lead screw 5.?. due to the action of clutch spring 54 and associated parts. Rotation of lead screw 52 causes follower nut 7b and the entire follower assembly to traverse the screw in a rearward direction, whereupon the drive bushing assembly is engaged and also is moved rearwardly to compress drive spring 75. Thus the bolt will also be pulled rearwardly by virtue of its connection with the drive bushing assembly, the action serving to turn the bolt head so it will unlock from the breech ring assembly. As the bolt travels rearwardly, drive bushing roller S4 contacts the edge of spiral slot Sdu in the belt feed tube to rotate the tube and to force the belt feed rack inward to thereby pull a cartridge toward the center of the cartridge belt feed way. In traveling rearward, the bolt is engaged by sear 200, and almost simultaneously engages and depresses tell tale 124 which in turn moves tell tale arm 122:1 and tell tale cam arm 125 rearwardly. The bolt remains locked in a rearward position by the sear. The tale switch arm 105 also moves rearwardly to open the power stroke circuit. At the same moment, because of the series connection between the charger motor fields and the magnetic brake, and due to the mechanical arrangement of brake and brake disc which provides for a small air gap, the brake is instantly applied, i. e., springs ill force armature 47 into engagement with brake disc Sii to immediately stop rotation of the motor shaft and rotating charger parts. Tell tale switch arm then engages contact 113 to energize the return circuit. This circuit is traceable from the tell tale switch through conduit 114, contacts 115 of switch 92, conduit 116 and return stroke field 117 and armature 110 of the charger motor to tend to turn the motor in counterclockwise direction. Since magnetic bra-ke 4l) is also series connected with the return stroke field of the motor, the brake is again energized to attract armature 47 which disengages brake disc 50 to permit counterclockwise rotation of the charger parts. `The lead screw now also turns counterclockwise through the action of the clutch spring, and the follower nut and follower parts now travel forwardly on the lead screw, however the drive bushing assembly and bolt remains locked in rearward position due to the fact that the sear abuts shoulder 202 of the bolt. The follower nut and follower cease moving forwardly when the nut encounters follower stop 63, however the lead screw keeps turning and is therefore forced rearwardly. This rearward movement is also transmitted to friction drive tube 26 and cam sleeve 31 causing beveled rear cam face 33 to engage upper shoe 96 of switch 92. The upper shoe pivots counterclockwise against spring 98 forcing lower shoe 95 and switch arm 93 downward until the lower contacts of switch 92 in the tiring circuit are engaged. Connections are now made to enable the firing of the gun and in tiring, loading switch 163 is opened and the trigger is actuated. Since the trigger is Connected to firing switch 122, by pressing the trigger this switch is closed and the sear operating solenoid is energized to depress the sear and tell tale, thereby energizing the firing circuit by Way of conduit 119, switch 92 to the sear operating solenoid. Th trigger may be pressed as long as desired for long or short bursts, and the bolt is now free to move back and forth actuated by the drive spring and usual recoil and countercoil mechanism. It is apparent that the charger motor is inoperative while the gun is tiring since contacts of switch 92 in the return stroke field, and loading switch 103 are open.

It can readily be seen that the provision of a magnetic broke insures positive and immediate stopping of the charger motor and thereby prevents over-running. The positive brake action has been found to be extremely effective to dissipate armature energy and to prevent excess forces from being transmitted to the lead screw and to the motor components.

Numerous other modifications and alterations of the structure which has been disclosed herein for purposes of illustration will be apparent to one skilled in the art and it is obvious that the same may be made without departing from the spirit and scope of the invention as defined in the following claims.

I claim:

l. ln combination with a machine gun having a reciprocatory bolt normally adapted to be retracted by recoil forces of a tired cartridge for automatically reloading the gun chamber, auxiliary mechanism for electrically charging the gun comprising, a reversible electric motor having selectively energizable field coils in series therewith and having a rotating shaft, a forwardly extending drive shaft having a splined connection with said motor shaft, a lead screw having a friction drive connection with said drive shaft and with a cylindrical friction drive tube concentric with said drive shaft, said friction drive tube having an enlarged portion on its rear end having a forwardly beveled rear cam face, a drive bushing forwardly mounted on said lead screw adapted to rearwardly traverse said lead screw, follower means on said lead screw forward of said drive bushing adapted to engage and to move said drive bushing rearwardly in response to clockwise rotation of said lead screw, a stud protruding downwardly from said drive bushing and received in a socket in said bolt, a magnetic brake located forwardly of said motor having a field winding connected.

in series with each of said motor fields, a brake disc mounted for rotation on said motor shaft, resilient means biasing said brake in engagement with said brake disc when said brake is deenergized, circuit means for selectively energizing each of said motor field coils, iirst normal open switch means in said circuit closable to energize oney of said eld coils to rotate said motor and lead screw clockwise and to simultaneously energize said brake to release said motor and said lead screw for clockwise rotation, said clockwise rotation of said lead screw causing rearward travel of said drive bushing to move said bolt from battery position to counterrecoil position, second switch means in said circuit cooperating with said bolt locking means and movable from first position, to deenergize said clockwise field and said brake to halt rotation of said motor and lead screw, to second position energizing said other tield in said motor and said brake to rotate said motor and lead screw in counterclockwise position, third switch means adapted to be engaged by said friction drive tube camface upon continued counterclockwise rotation of said lead screw to deenergize said brake and second counterclockwise field to halt rotation, and normally open firing switch in said circuit elosable to release said bolt to lire said gun.

2. ln combination with a machine gun, an electrically operated charging and reloading mechanism comprising a housing, a motor in said housing, a lead screw having a driving connection with said motor, a reciprocatory bolt for said gun, a cartridge belt feedway, means connecting said leadl screw with said bolt, means connecting saidk lead screw with said belt feedway adapted to place a cartridge from said feedway into loading position in response to rearward movement of said bolt, an electric power source, means to connect said motor with said power source to rotate said lead screw in one direction to retract said bolt from battery position to counterrecoil position, means to lock said bolt in counterrecoil position, switch means interposed between said power source and said motor simultaneously operable with said bolt locking means to brake rotation of said motor and to rotate said motor and lead screw in opposite direction, and second switch means actuable on continued rotation of said lead screw in said opposite direction adapted to brake rotation of said motor and lead screw to enable pressure on the trigger of said gun to `release said bolt to lire said gun, Vsaid means to brake rotation of said gun comprising a flat, annular solenoid housing including a field winding concentric with said motor driving connection and tixedly secured to the forward face of said motor housing, a brake disc keyed to said motor driving connection for rotation therewith, a disc-shaped armature interposed between said solenoid housing and said brake disc, resilient means securing said armature to the forward face of said motor housing and normally biasing said armature into` engagement with said brake disc when said field winding is deenergized.

3. In combination with a machine gun, an electrically operated charging and reloading mechanism comprising a cup-shaped housing, a reversible motor in said housing and a motor shaft extending through the forward face of said housing, a magnetic brake having a winding connected in series with said motor, comprising a centrallyapertured disc-shaped member secured to the forward face of said housing and concentric about said motor shaft, there being an annular recess in the forward face of said disc-shaped member for receiving said winding, a lead screw having a splined connection with the shaft of said motor, a brake disc mounted on said lead screw for rotation therewith and with said motor, a disc-shaped armature interposed between said disc-shaped member and said brake disc, resilient means normally biasing said armature into engagement with said brake disc, a reciprocatory bolt for said gun, a cartridge belt feedway, means connecting said lead screw with said bolt, means connecting said lead screw with said belt feedway adapted to place a first cartridge from a cartridge belt on said feedway into charged position when said bolt is moved rearwardly, an electric power source for energizing said winding to thereby withdraw said armature against the bias of said resilient means to release said brake and rotate said motor in one direction to retract said bolt from battery position to counterrecoil position, means to lock said bolt in retracted position, switch means interposed between said power source and said motor simultaneously operable with said bolt locking means to halt the direction of rotation of said motor and lead screw and to reverse rotation of said motor and lead screw, and second switch means actuable on continued rotation of said motor and lead screw in said reverse direction adapted to deenergize said winding to brake rotation of said motor and said lead screw and to enable pressure on the trigger of said gun to release said bolt to fire said un. g 4. In combination with a machine gun having a reciprocatory bolt normally adapted -to be retracted by recoil forces of a tired cartridge for automatically reloading the gun chamber, auxiliary mecahnism for electrically charging the gun comprising, a cup-shaped cylindrical housing, a reversible electric motor received in said housing and having selectively energizable field coils -in series therewith and a rotating shaft extending through a forward face in said housing, a forwardly extending drive shaft having a splined connection with said motor shaft, a lead screw having a friction drive connection with said drive shaft and with a cylindrical friction drive tube concentric with said drive shaft, said friction drive tube having an enlarged portion on its rear end providing a forwardly beveled rear cam face, a drive bushing forwardly mounted on said lead screw adapted to rearwardly traverse said lead screw, follower means on said lead screw forward of said drive bushing adapted to engage and to move said drive bushing rearwardly in response to clockwise rotation of said lead screw, a stud protruding downwardly from said drive bushing and received in a socket in said bolt, a magnetic brake having a field winding connected in series with each of said motor elds and comprising a centrally apertured disc-shaped member secured to the forward face of said motor housing and concentric about said motor shaft, there being an annular recess formed in the forward face of said discshaped member to provide a housing for said field winding, a brake disc keyed to rotate with said motor shaft and spaced axially forwardly of said disc-shaped member, a disc-shaped armature interposed between said discshaped member and said brake disc, resilient means secur` ing said armature to the forward face of said motor housing and urging said armature into engagement with said brake disc when said field winding is deenergized, circuit means for selectively energizing each of said motor field coils, first normally open switch means in said circuit closable to energize one of said field coils to rotate said motor and lead screw in a clockwise direction and to simultaneously energize said eld winding 'to release said motor and said lead screw for clockwise rotation, Isaid clockwise rotation of said lead screw causing rearward travel of said drive bushing to move siad bolt from battery position to counterrecoil position, second switch means in said circuit cooperating with said bolt locking means and movable from first position, to deenergize said clockwise field and said field winding to halt rotation of said motor and lead screw, to second position energizing said other eld in said motor and said field winding to rotate said motor and lead screw in counterclockwise position, third switch means adapted to be engaged by said friction drive tube cam face upon continued counterclockwise rotation of said lead screw to deenergize said field winding and second counterclockwise field to halt rotation, and normally open tiring switch -in said circuit closeable to release said bolt to tire said gun.

5. In combination with a machine gun having a reciprocatory bolt normally adapted to be retracted by' recoil forces of a fired cartridge for automatically reload ing the gun chamber, auxiliary mechanism for electrically charging said gun and comprising an elongated cylindrical belt fed ltube mounted for oscillation adjacent said gun and along the path of movement of said bolt, there being a spiral slot in said belt feed tube engageable by said reciprocatory bolt to oscillate said belt feed tube, a cartridge belt feedway mounted laterally of said belt feed tube, means on said tube providing a driving connection between said tube and said belt feedway for moving a cartridge into position into said gun chamber in response to retraction of said bolt, a reversible motor mounted adjacent the rear end of said belt feed tube and having a forwardly extending drive shaft extending concentrically within said belt feed tube, a lead screw concentric within said belt feed tube and extending forwardly of said drive shaft, means providing a drive connection between said drive shaft and said lead screw, a traversing nut mounted on said lead screw, a drive bushing mounted on said lead screw adapted to be engaged by said traversing nut for rearward movement in response to clockwise rotation of said lead screw, means providing a fixed connection between said bolt and said drive bushing, a drive spring concentric about said drive shaft normally biasing said drive bushing forwardly against said traversing nut, said motor having a power field energizable -to rotate said lead screw clockwise and a return ield for rotating said lead screw counterclockwise, a magnetic brake mounted rearwardly of said motor and having means resiliently biased to normally engage said 11 drive `shaft and `to lock said shaft against rotation, a brake winding in said brake Connected in `series with said power and return elds energizable to release said brake to permit rotation of said drive shaft, circuit means for selectively energizing each of said motor field coils, rst normally open switch means in said circuit closable to simultaneously Venergize said brake winding to disengage said drive shaft and to permit clockwise rotation of said lead screw to thereby move said bolt from battery to counterrecoil position, means in said gun adjacent the rear end of said belt feed tube for locking said bolt in counterrecoil position, a selector switch in said circuit cooperating with said bolt locking means selectively movable from first position to deenergize said clockwise field and said brake winding to halt clockwise rotation, to second position energizing said return eld and said brake winding to permit counterclockwise rotation of said eld and 4to return said traversing nut to the forward end of said lead screw, a third switch in said circuit closable upon continued counterclockwise rotation of said lead screw to deenergize said brake winding and said kreturn field, and a normally-open tiring switch closable to withdraw said bolt locking means, whereby said bolt is released -to re said gun.

References Cited in the le of this patent UNITED STATES PATENTS 1,961,349 Gordon June 5, 1934 2,180,751 Wagner Nov. 2l, 1939 2,413,241 Mejean et al. Dec. 24, 1946 2,413,416 Astlund et al. Dec. 3l, 1946 2,472,002 Clark May 3l, 1949 FOREIGN PATENTS 914,885 France July 1, 1946

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