US2750845A - Belt feed mechanisms for automatic firearms - Google Patents

Description

June 19, 1956 B. MAILLARD BELT FEED MECHANISMS FOR AUTOMATIC FIREARMS Filed March 25; 1952 5 Sheets-Sheet 1 ATTORNEY June 19, 1956 MAlLLARD 2,750,845

BELT FEED MECHANISMS FOR AUTOMATIC FIREARMS Filed March 25, 1952 5 Sheets-Sheet 2 V: Z w 4 M g r wm 0 M 6 W 5 R M v Q w \i m a E A mw V /\-oh\ \l m7 5% 0 ww z w as h NW mm VQMKQ wn June 1956 B. MAILLARD BELT FEED MECHANISMS FOR AUTOMATIC FIREARMS Filed March 25, 1952 5 Sheets-Sheet 5 wmgb NM [G j? \K v Q H viii i i w fi s. wh v. N U W 15 a WN A l: w 5. II, m mm so i iii w w w w \w m m J I l| 1 0w 3 I I :mfl immmmmihm Ff? W I. %N \W m NNIII l -i L. i -H I 1 h p h ,M M Q 5 5 W M 3 @y !L XL Tn NH HQ. mNHQ A 770/? NE Y June 19, 1956 B. MAILLARD BELT FEED MECHANISMS FOR AUTOMATIC FIREARMS 5 Sheets-Sheet 4 Filed March 25, 1952 ATTORNEY June 19, 1956 B. MAILLARD 2,750,845

BELT FEED MECHANISMS FOR AUTOMATIC FIREARMS Filed March 25, 1952 5 Sheets-Sheet .5

INVENTOR MRQIZA BELT FEED MECHANISMS FOR AUTOMATIC FIREARMS Bernard Maillard, Geneva, Switzerland, assignor to Society Brevets Aero-Mecaniques, S. A., Geneva, Switzerland, a society of the Republic of France Application March 25, 1952, Serial No. 278,349

Claims priority, application Luxemburg March 27, 1951 7 Claims. (CI. 8933) The present invention relates to belt feed mechanisms for automatic firearms to which ammunition is fed in the form of cartridge belts. The term belt feed mechanism is meant to include any mechanism capable of moving the cartridges toward the arm and feeding them successively thereto during firing. My invention is more especially, but not exclusively, concerned with firearms the breechblock of which is released through means other than the recoil of the arm, for instance by a gas tap.

The object of my invention is to provide a firearm of this kind which is better adapted to meet the requirements of practice than those existing at the present time.

My invention is concerned with indirect action belt feed mechanisms for use with belts having open links, that is to say to belt feed mechanisms with which the cartridges, after they have been released from their links by a transverse relative displacement, must still be given a transverse displacement (generally a downward vertical displacement) through an introduction passage to come into a position from which they are engaged into the firearm cartridge chamber by the breech block with a substantially axial movement. According to my invention, in order to pull, during every step of the movement of the rotary element (rotor) of the belt feed mechanism, every belt link from the cartridge to be detached from the belt, I combine means forming a radial abutment for the cartridges engaged with the rotor and still held by the links (or at least one link) of the belt, with a pulling hook carried by a part movable in such manner that it is pushed back, preferably by the wall of the cartridge to be released, from the beginning of every step of the rotor, in the direction for which the link is pulled off from said cartridge under the effect of the rotation of the rotor. Advantageously the nose of this pulling hook is elastically urged back, once the cartridge has been released, toward the rotor so that it occupies, at the end of every pitch, a position such that the front end of the next link to be pulled off is then in engagement with said nose.

Other features of my invention will become apparent in the course of the following detailed description of an embodiment thereof with reference to the accompanying drawings, given merely by way of example, and in which:

Fig. 1 is a general elevational view of a firearm of the kind with which the present invention is concerned;

Fig. 2 is a sectional view of the belt feed mechanism according to my invention, on the line II-II of Fig. 9;

Fig. 3 i a sectional view on the line IIIIII of Fig. 9- Figs. 4, 5 and 6 are three sectional views on the line "IVIV of Fig. 9;, showing three successive relative positions" of the-parts, respectively; I Fig. 7 is a sectional view on the line VIIVII of e- .9; Fig.8 shows a detail of Fig. 4;

Fig. 9 is a vertical view a portion of which shows a section on the line IXaI Xa of Fig. 2 and another portion a section on the line IXb -IXb of Fig.2;

-' is'a horizontal; view a portion of which shows.

I nited rates atent a section on the line Xa-Xa of Fig. 2 and another portion a section on the line XbXb of Fig. 2;

Fig. 11 is a perspective view showing the essential elements of the belt feed mechanism, separately from the other parts;

Figs. 12 and 13 are perspective views showing, respectively, a separate link, and two interconnected links of a belt such as used with the belt feed mechanism illustrated by the other figures.

The firearm with which my invention is concerned includes a barrel 1 rigid at the rear with the breech case 2 in which reciprocates a breech block 3 urged frontwardly by a recuperator spring 4 and controlled, concerning its release, by a gas tap system 5.

The whole of these elements, which constitutes the firearm proper, is slidable in a fixed support or cradle 6, an elastic system '7 being interposed to absorb the recoil of the firearm with respect to its support and to return it frontwardly.

Rigid with support 6 there is provided a plate 8 (magazine carrier) intended to receive the belt feed mechanism 9 which will be hereinafter described. For instance, as shown, this piate 8 is linked to support 6 by an arm 10 and the upper edge of the breech case slides on the under face of said plate during the reciprocating movements of the firearm.

Plate 8 is provided with means for securing the belt feed mechanism thereto in a detachable fashion, such means being for instance constituted at the front by a tenon-and-mortise connection 11 and at the rear by a retractable locking finger 12.

According to a conventional arrangement, shown by way of example, the belt feed mechanism is operated by the displacement of the firearm proper during a portion (hereinafter called active portion) of its recoil with respect to support 6, this displacement being imparted to the belt through a transmission which will now be described.

The belt feed mechanism frame essentially includes two transverse plates 13 and 14 (Fig. 9) located respectively at the front and at the rear of this mechanism, with suitable rods interconnecting them.

The front plate 13 carries a mechanism cooperating with a device which participates in the recoil movement of the firearm to rotate a shaft element 15 (Figs. 2 and 3), parallel to the direction of fire, through a given angle every time a shot is fired, this shaft element 15 being journalled in said front plate 13.

This last mentioned mechanism includes the following elements shown in Fig. 9:

Front plate 13 carries a vertically sliding member 16, urged downwardly by a spring 17 interposed between a horizontally projecting flange of member 16 and a horizontally projecting flange 13a of plate 13, this sliding member 16 carrying a spindle 18 parallel to shaft element 15 and on which a pinion 19 is freely journalled.

The front portion of the firearm breech casing carries, pivoted about a horizontal axis 21, a longitudinal arm 20 the rear end of which carries, projecting from its under face, a roller 22 arranged to cooperate with a ramp 23 advantageously carried by a plate 13 rigid with plate 13 and which forms the front wall of the belt feed mechanism body. During at least a portion of the recoil movement of the firearm, the rear end of arm 20 is moved upwardly against the action of a return spring.

The top face of this rear end of arm 20 forms a ramp 24 arranged to cooperate with a roller 25 carried by sliding member 16 so that, during at least a portion of the recoil stroke of the firearm, this sliding member 16 is pushed upwardly against the thrust of spring 17, under the simultaneous effects of the upward movement of the rear end of arm 20 and of the slope of ramp 24, which produces a supplementary u ward movement of roller 25.

On either side of sliding member 16 (Fig. 3), and respectively on shaft element 15 on a spindle 26 parallel thereto and freely journalled in plates 1-3 and 13, I provide two pinions 27 and 28, for instance both of the same diameter as pinion 19', in mesh therewith.

These pi'nions 27 and 28 are rigid with ratchet wheels 29 and 30 respectively (Fig. 2), these ratchet wheels cooperating with respective pawls 31 and 31 arranged so that, when sliding member 16 is moving upwardly, pinion 28 is prevented from rotating and pinion 27 is rotated whereas, when sliding member 16 is moving downwardly, pinion 27 is prevented from rotating backward whereas pinion 29 turns freely. k

Such a mechanism will therefore impart a rotary movement of a given amplitude to pinion 27 upon every recoil displacement of the firearm, this movement taking place during the active portion of the recoil period, which portion is advantageously limited to that corresponding to the minimum amplitude recoil.

I will now describe how this movement is transmitted to the rotating portion of the belt feed mechanism.

This rotating portion includes a shaft 32 (Figs. 9, 10 and 11) substantially parallel to the direction of firing and journalled in plates 13 and 14. This shaft carries, fixed thereon, a plurality of (three in the present example) toothed Wheels 32a which constitute what will be hereinafter called the rotor of the belt feed mechanism. The teeth of this rotor are arranged to be interposed between the cartridges of the belt, so as to drive this belt. Shaft 32 is preferably positioned so that the cartridge belt, which enters the mechanism horizontally, as shown by Figs. 4, and 6, is deflected downwardly, at about 90 to its initial direction, toward the feed or introduction passage 33 of the arm.

Shaft element 15 is connected to shaft 32 as follows:

In a tubular sleeve 34 (Figs. and 11) extending between plates 13 and 14 and parallel to shaft 32 are mounted, in end to end relation to each other, two sleeves 35 and 36 the respective ends of which adjacent to each other are provided with cooperating dogs or projections 3738 such that a relative angular displacement of a maximum amplitude equal to a is possible between these two last mentioned sleeves. I

The outer end of sleeve 35 is fixed to pinion 27, and therefore to shaft element 15.

The outer end of sleeve 36 is fixed to a pinion 39 disposed close to the rear end plate 14, this pinion 39 being rigid with a shaft element 40 journalled in said plate 14.

I interpose between shaft elements and 40, inside sleeves 35 and 36, a torsion spring 41 initially stressed so that it tends to rotate pinion 27 with respect to pinion 39 in the direction opposed to that of the rotation imparted to said pinion 27 during the active portion of the recoil movement of the firearm. V

I journal in plate 14, coaxially with shaft 32 (which is tubular) a pinion 42, for instance identical to pinion 39, this pinion 42 being rigid with a shaft element 43.

Inside the front portion of hollow shaft 32 and rigid therewith, there is provided a shaft element 44.

The rear end of hollow shaft 32 and the edge of pinion 42 adjacent to this shaft end are provided with cooperating dogs or projections 45, 46, respectively, such that a relative angular displacement of a maximum amplitude equal to b is possible between pinion 42 and shaft 32 (which carries the rotor).

I interpose between shaft elements 43 and 44, inside shaft 32, a torsional spring 47 initially stressed so that it acts in the same direction as torsional spring 41.

Finally, between pinions 32 and 42 there is interposed a pinion 48 in mesh with both of these pinions.

It will be readily understood that, if the sum of rotation angles a and b is smaller than the amplitude of the rotation of pinion 27, a temporary resistance opposed to the rotation of rotor 32a will deform springs 41 and 47 and if this resistance reaches a given value, i. e. if the angular deformations of these springs become equal to a and 1) respectively, sleeve 35 will directly engage sleeve 36, through their projections 37 and 38 (Fig. 11) whereas the tubular extension of pinion 42 will directly engage shaft 32, through their projections 45 and 46. This will substitute, between shaft element 15 and rotor 32a, a positive or abutting transmission for the elastic transmission exerted by springs 41 and '47. Owing to this positive power transmission, the resistance opposed to the rotation of rotor 32a will be overcome, after which springs 41 and 47 will expand back and return the various parts to their initial relative positions before the end of the movement of rotor 32a corresponding to one pitch.

By way of example the angle through which pinion 27 rotates may be equal to and the sum of angles a and b to 50.

Such a belt feed mechanism has the following chief advantages:

The elastic elements of the transmission, acting as energy accumulator means, impart flexibility to the system.

The fact that pinion 27 is prevented from moving backward by its pawl 31 makes it possible to obtain that the pitch displacement of the belt takes place during a period ending after the end of the active portion of the recoil movement of the firearm, an important result in View of the relatively high inertia of the belt.

The absence in the belt feed mechainsm of elements which would have to be moved back while the firearm is returning toward its front position and the inertia of which would therefore slow down this frontward return movement of the firearm makes it possible to obtain a higher rate of fire.

Finally, since, at the end of every pitch, no torque is being exerted on the rotor, no thrust is being exerted upon the last cartridge a (Fig. 6) which has just been engaged into the introduction passage.

I will now consider the removal of the cartridges from their links in order to introduce them into the firearm.

It should first be noted that all that has been explained above concerning the belt feed movement remains true in the case of a firearm of the direct feed type, i. e. if the first cartridge to be introduced is brought, by the forward movement of the belt corresponding to one pitch, across the path of travel of the cartridge catching projection of the breech block, the cartridge being pulled off from its link during the frontward, substantially axial, movement of the breech block, which pushes the cartridge into the cartridge chamber of the firearm.

If, on the contrary, as it will be hereinafter supposed by way of example, the firearm is of the indirect feed type, it is advantageous to make use of another feature of my invention, which may be used irrespective of what particular kind of belt feed mechanism is being used. However, the particular example of this feature which will now be described corresponds to the case where the belt feed mechanism is of the type above described, referring particularly to Figs. 4 to 8.

The successive cartridges, pulled ofi from their links, are to be engaged downwardly into the vertical introduction passage 33. The rotor is supposed to include five teeth, i. e. to form five circular notches for five successive cartridges of the belt.

The mechanism includes radial abutment means for the cartridges present in the notches of the rotor and still in mesh with at least one link. Such means are constituted, in the example shown by the drawing, by guiding surfaces or ramps 62 in the form of circular arcs forming the geometrical envelopes of the cross sections of the cartridges engaged by the rotor.

The first link 49 is pulled oil? from the cartridge to be released (which cartridge is being held radially by ramps 62) by means of a pulling hook carried by a lever 50 and arranged in such manner that, at the beginning of every feed step of the mechanism, its nose 51 meets the front end r (Fig. 12) of the link 49 to be pulled off. At this time, said link is still engaged on the cartridge which, at the end of this feed step, is to be disengaged from said link and engaged in the top end of introduction passage 33.

This lever 50 is disposed substantially vertically and .is L-shaped so that its horizontal branch, which carries nose 51 at its end, comes, at the beginning of every feed step of the mechanism, as shown by Fig. 4 (lever 50 being then applied against abutment 56 which limits its move- :ments in the anti-clockwise direction) into contact with the case of the cartridge engaged in link 49, nose 51 en- :gaging under the end 2' of said link.

The upper edge 52 (Fig. 8) of this horizontal branch of lever St) is so shaped that under the effect of the rotation of the rotor, the cartridge (held radially by surfaces 62,) slides on this edge while pushing lever 50 to rotate it about its axis 53, against the action of a return spring 54, away from the rotor. In the course of this movement, nose Si pulls the end 1' of link 49 away from its cartridge, so that finally (Fig. 5) the front loop of link 49 is disengaged from the cartridge around which it was fitted. This cartridge is further driven by the rotor downwardly until, at the end of the feed step (Fig. 6), it is engaged between the upper edges of introduction passage 33.

The nose 51 of lever 56 extends downwardly toward the left (as visible in Figs. 4, 5, 6 and 8) to form an inclined surface 55 which, in the course of the feed step of the rotor, gradually guides the front end of link 49 farther and farther away from the rotor axis so that, at the end of the rotation of lever 50 toward the left, this inclined surface has brought the end of link 49 to the top of a fixed evacuation sloping surface 56 along which the link is to be guided.

Advantageously, and in particular when the links are of the rigid type as shown by Figs. 12 and 13, having their front loop constituted by two curved strips 58a, 58b intended to surround thecartridge on either side of the rear loop of the preceding link, I make use of two levers 50 located at a distance from each other such that they can cooperate respectively with these two strips 58a, 58b.

The noses 51 and inclined surfaces 55 of these two levers 50 are then advantageously provided on side projections provided on levers 50 and turned toward each other, the fixed evacuation surface 56 being disposed between these two projections.

In order to obtain that the pulling off of the front loop of the first link also pulls off the rear loop of the preceding link, it is advantageous to make use of links as shown by Figs. 12 and 13. With such links, the rear loop of every link is provided with two small flanges 57a and 57b which overlap the strips 58a and 58b forming the front loop of the next link. Thus, when these strips 58a, 58b

are pulled off, they drive together with them, through flanges 57a, 57b, the rear loop of the preceding link.

It will be readily understood that the distance between the axes of two successive cartridges increases a little between the time when nose 51 starts acting and that when the cartridge, prevented by guiding surfaces 62 from moving radially away from the axis of the rotor, causes the front loop of link 49 to move away from the rotor. In order to allow for this temporary variation of the distance between successive cartridges, the rotor is advantageously made in such manner that its teeth engage the cartridges with a play suflicient to enable, during the pulling off of the front loop of a link, the cartridge engaged in this link to move the desired distance with respect to the next cartridge of the belt, this last mentioned cartridge remaining applied against the rear surface of the notch between two teeth in which it is housed.

I will now describe still another feature of my invention.

It is known that in the belt feed mechanisms of the rotor type, as known up to the present time, the rotor acts upon the cartridge in introductory position either directly through its teeth or indirectly through the intermediary of at least one cartridge located between the rotor and said cartridge in introduction position, so as to apply it upon the lips 33a (Fig. 6) of the introduction passage.

In view of the fact that the torques necessary to drive the belt are becoming greater and greater due to the higher and higher rates or fire requirements and to the heavier and heavier cartridges that are being used, the fact that the force resulting from this torque is transmitted to the cartridge in introductory position causes said cartridge to be applied against the edges of the introduction passage with a pressure which may have a detrimental efiect on the good operation of the firearm.

In order to obviate this drawback, according to my invention,

on the one hand I provide an elastic thrust cam 60 arranged to exert, at the end of every feed step of the belt feed mechanism, a transverse thrust directed toward the firearm on the last cartridge a (Fig. 6) which has just been engaged into the introduction passage, and

on thelother hand, at the same time, this cartridge a is no longer subjected to the driving action of the rotor, whereby cartridge 17 in introductory position is subjected merely to the thrust of the elastic cam.

With the particular belt feed mechanism above described, as above explained, at the end of every feed movement there is no longer any driving torque exerted upon the rotor, which is then abutting, through the last cartridge still engaged in its link, with the horizontal branch of lever 50, and, accordingly, no thrust is transmitted by the rotor to cartridge a.

But if the rotor were driven in a difierent way, for instance by means of a torque existing constantly, an abutment might be used to stop the rotor at the end of every feed step, and therefore to prevent it from pushing cartridge a toward the firearm.

The elastic cam arrangement 60 may for instance be constituted by two deflecting fingers freely rotatable about the hollow shaft 32 of the rotor and cooperating respectively with the front and rear portions of the cartridge case. The cartridge which is moving down (Fig. 5) causes these fingers to retract against the action of a spring 61 and then these fingers (Fig. 6) come to bear upon said cartridge (cartridge a, Fig. 6) to push it toward the firearm.

Thus, the pressure transmitted by this cartridge a to cartridge b in introductory position is independent of the torque exerted by the rotor for driving the belt. This pressure depends solely upon the strength of the springs 61 of the deflecting fingers 60.

Therefore, with the kind of firearm according to the present invention, when the breechblock is in front position (Fig. 5), due to the position of the rotor and the deflecting fingers, the cartridge in waiting position rests without pressure upon the breechblock. It is in contact neither with the deflecting fingers nor with the rotor. After the shot is fired, the breechblock moves backward under the cartridge in waiting position and initially this cartridge is not subjected to any pressure. Then due to the recoil of the firearm, which causes the rotor to work, the pressure on said cartridge increases (being transmitted by the next cartridge) until, under the effect of this pressure, this cartridge passes (the breechblock being then retracted) from waiting position 0 (Fig. 5) into introductory position b (Fig. 6), where it is pushed toward the firearm only by the action of deflecting fingers 60 transmitted through cartridge 11.

It will be understood that the first above mentioned feature of my invention relating to the operation of the belt feed mechanism is particularly interesting when the cartridges are pulled off from their links by means of a device as described with reference to Figs. 4, 5, 6 and 8.

This is due to the fact that, as the disengagement of the cart-ridges from their links is produced under the action of the force transmitted by the rotor, temporary high resistances develop at the beginning of every step of this rotor, when it is called upon not only to feed the cartridge belt forward but also to pull one cartridge therefrom. At this time, springs 41 and 47 are generally caused to yield and the movement is transmitted to the rotor positively from shaft element 15 through cooperating projections 3738 and 45-46. Once this resistance has been overcome, the energy accumulated in the springs sufiices to finish the step.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efficient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

I. For use in connection with an indirect feed automatic firearm, a belt feed mechanism which comprises, in combination, a cartridge belt constituted by a plurality of cartridges and open links for interconnecting them, a frame, a rotor journalled in said frame provided with teeth engaging between the cartridges of said belt, means for rotating said rotor step by step in response to the firing of every shot by said firearm, guiding means carried by said frame around a portion of said rotor for preventing outward radial movement of the cartridges engaged by said rotor and still engaged with at least one link of said belt, a part movable in said frame away from and toward said rotor adapted to cooperate with one of the cartridges present in said rotor to be pushed by said cartridge away from said rotor at the beginning of every step of the rotation thereof, spring means interposed between said frame and said part for urging the latter toward said rotor to return it into its initial position at the end of every step, and a hook carried by said part to engage under the front end of the link surrrounding the first cartridge of said belt, whereby the movement of said part away from said rotor causes said hook to pull off said link from said cartridge.

2. For use in connection with an indirect feed automatic firearm, a belt feed mechanism which comprises, in combination, a cartridge belt constituted by a plurality of cartridges and open link for interconnecting them, a frame, a rotor journalled in said frame provided with teeth engaging between the cartridges of said belt, means for rotating said rotor step by step in response to the firing of successive shots by the firearm, guiding means carried by said frame around said rotor, the sections of said guiding means by planes perpendicular to the axis of said rotor being substantially circular and coaxial with said rotor, an introduction passage carried by said frame having its middle plane substantially parallel to the rotor axis, the inlet of said passage being joined with the outlet of said guiding means, a lever pivoted to said frame about an axis parallel to the rotor axis, said lever carrying a transverse bar adapted to cooperate with the cartridge of said belt which is nearing the end of said guiding means so as to be pushed away from said rotor by said cartridge, a hook carried by the end of said transverse bar to engage under the front end of the link surrounding this cartridge, whereby the pivoting of said lever when its transverse bar is pushed back by said cartridge causes said hook to pull off said link therefrom, an abutment carried by said frame adapted to cooperate with said lever to limit its movement toward said rotor to the position for which said hook engages under the front end of the link of the first cartridge to be disengaged, and spring means interposed between said frame and said lever for urging the latter toward said abutment.

3. A belt feed mechanism according to claim 2 in which the top edge of the transverse bar of said lever is sloping downwardly toward the rotor to cooperate with the case of the first cartridge to be disengaged from the belt.

4. A belt feed mechanism according to claim 2 further including, on said lever, an inclined surface starting from said hook thereof and sloping away from both the lever pivot axis and the rotor axis.

5. A belt feed mechanism according to claim 2 in which every link includes a front loop constituted by two curved strips adapted to surround respectively the front and the rear of the corresponding cartridges, said lever being double to engage both of said strips.

6. A belt feed mechanism according to claim 2 in which every link includes a front loop constituted by two curved strips adapted to surround respectively the front and the rear of the corresponding cartridges, said lever being double to engage both of said strips, the hooks of each lever element being disposed on side projections thereof turned toward each other.

7. A belt feed mechanism according to claim 2 in which the intervals between the teeth of the rotor accommodate the cartridges with a slight play to make allowance for small variations of the distance between the axes of two successive cartridges during the pulling off from the belt of the first of these two cartridges.

References Cited in the file of this patent UNITED STATES PATENTS 2,436,370 Alexander Feb. 24, 1948 2,453,786 Dixon Nov. 16, 1948 FOREIGN PATENTS 909,996 France May 23, 1946

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