US3744371A

US3744371A - Selective dual feed mechanism

Info

Publication number: US3744371A
Application number: US00199967A
Authority: US
Inventors: L Mcfarland
Original assignee: US Department of Army
Current assignee: US Department of Army
Priority date: 1971-11-18
Filing date: 1971-11-18
Publication date: 1973-07-10
Anticipated expiration: 1990-07-10
Also published as: CA958575A

Abstract

A dual feed mechanism for selectively feeding cartridges from one of two cartridge belts into a firearm receiver comprises a Scotch yoke which is reciprocated by a rotary crank and which carries in each of the two extending arms a laterally spring pressed pin. A switch is located between the two pins so that when displaced against either, that pin is pressed into engagement with a related bell crank for actuation thereof and the other pin is disengaged from a similar bell crank. Each of the bell cranks is connected to a slide which is reciprocated thereby and which carries a pawl that moves one of the two cartridge belts into the receiver responsive to slide reciprocation.

Description

ilnited States Patent 1 1 3,744,371

McFarland 1 July 10, 1973 SELECTIVE DUAL FEED MECHANISM [75] Inventor: Larry C. McFarland, Silvis, Ill. PmTMUy Borche" Assistant ExammerJ. V. Doramus 1 Ass1gnee= The United States of America as Attorney-Harry M. Saragovitz, Edward J. Kelly represented by the Secretary of the et 1 Army, Washington, DC.

22 Filed: Nov. 18, 1971 [57] ABSTRACT A dual feed mechanism for selectively feeding car- [2]] Appl' 199367 tridges from one of two cartridge belts into a firearm receiver comprises a Scotch yoke which is reciprocated [52] US. Cl. 89/33 SF by a rotary crank and which carries in each of the two [51] Int. Cl. F4111 9/00, F4ld 9/02 extending arms a laterally spring pressed pin. A switch [58] Field of Search 89/33 SF, 129, 130; is located between the two pins so that when displaced 42/1, 18 against either, that pin is pressed into engagement with a related bell crank for actuation thereof and the other [56] References Cited pin is disengaged from a similar bell crank. Each of the UNITED STATES PATENTS bell cranks is connected to a slide which is reciprocated thereby and which carries a pawl that moves one of the 3,455,204 7/1969 Stoner 89/33 SF two cartridge belts into the receiver responsive to slide FOREIGN PATENTS OR APPLICATIONS reciprocation 1,142,380 2/l969 Great Britain 89/33 SF 4 Claims, 6 Drawing Figures SELECTIVE DUAL FEED MECHANISM BACKGROUND OF THE INVENTION This invention pertains to feed mechanisms for automatic guns and relates more particularly to such feed mechanisms whereby cartridges can be selectively fired from one of two cartridge belts.

In the highly specialized field of modern warfare, cartridges of the same caliber have been developed with different military characteristics. It is also the principal object of modern ordnance to provide the troops with the greatest degree of firepower as possible. The present invention advances this object by providing automatic guns with feed mechanisms whereby cartridges may be easily selected for fire from two different car tridge belts which may comprise cartridges of different military characteristics.

SUMMARY OF THE INVENTION It is a particular object of this invention to provide for automatic guns a dual feed mechanism whereby feed may be changed from one cartridge belt to the other by a flip of a switch during a firing burst or between bursts.

It is another object of this invention to provide such a feed mechanism which is simple in design, rugged in construction and positive in operation.

Selective dual feed in the present invention is achieved through a Scotch yoke which converts rotary power input to translational movement and spring pressed pins which are each mounted through one of the extending bars of the yoke for selective engagement with one of two bell cranks. Each of the bell cranks is connected to a slide carrying an actuating pawl disposed in cooperation with a holding pawl for feeding one of two cartridge belts into the firearm receiver. Selection of one of the two cartridge belts for feeding is made by a slidable switch which, responsive to sliding displacement thereof, presses one of the pins into engagement with the respective slide, for activating the actuating pawl thereon, and disconnects the opposite pin from its respective slide.

Further objects and advantages of the invention will become apparent from the following specification and the accompanying drawings which are for the purpose of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a fragmentary side view of a portion of an automatic gun in the area of the feed mechanism, with the near side plate of the receiver removed to show the feed mechanism wherein the upper one of the the pawl carriers is in the closed position and the lower one is in the open position;

FIG. 2 is a top view of the same area shown in FIG. 1 with the top of the receiver removed to show the feed mechanism inside;

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 1 but showing the carriers in their closed positions;

FIG. 5 is a cross-sectional view taken along line 55 of FIG. 3; and

FIG. 6 is a fragmentary, partially broken away isometric view of the switch mounted to the top of the receiver.

DESCRIPTION OF A PREFERRED EMBODIMENT Shown in the drawings is a firearm receiver 12 which mounts a bolt 14 for longitudinal reciprocation and a feeding mechanism 16 adapted, as hereinafter described, for selectively feeding cartridges 18 from one of two cartridge belts 20 in position for pickup and chambering by the bolt. Cartridges [8 in each of the two cartridge belts 20 are preferably of different military characteristics.

Feed mechanism 16 comprises a housing 22 and a Scotch yoke 24 sliding disposed therein for longitudinal reciprocation. Yoke 24 is of U-configuration, as shown in FIG. 1, and includes a pair of bars 26 which extend forwardly from opposite ends of a crossbar 28. Longitudinal reciprocation of yoke 24 is effected by a power input such as a rotary crank 30 comprising a crankpin 32 which is disposed within an elongated slot 34 in crossbar 28 thereby converting rotation of the crank to translation of the yoke. Mounted for sliding lateral displacement through the free end of each of the bars 26 is a pin 36 which is biased in the direction of the center line of yoke 24 by a spring 38 that is compressed between head 40 of the pin and the adjacent side of the respective bar, as shown in FIG. 1. Heads 40 bear against opposite sides of blade 42 of a switch 44 more fully described hereinafter.

A feed belt carrier 46 is pivotally mounted at the front end thereof, by hinge means 48, to each side of housing 22 so that it can be swung from a closed position to an open position for loading one of the two cartridge belts 20 to feed mechanism 16. Carriers 46 are secured in their closed positions by suitable means. Each carrier 46 is provided with a slide 50, disposed thereon for horizontal reciprocation, and a bell crank 52, comprising a first arm 54 and a second arm 55 angularly related thereto, which is rotatingly mounted to the carrier by a stud 56. Provided on the end of first arm 54 is a rectangular lug 57 which includes a horizontally disposed channel 58 and a pair of cam surfaces 60 which extend angularly from the front and rear sides, respectively, of the lug to the adjacent edge of the channel, as shown in FIG. 1. Channel 58 is disposed for receiving outer end 62 of the respective pin 36, when the related carrier 46 is closed and the pin is pressed outwardly by switch 44, whereby the related bell crank 52 is connected to yoke 24 for converting longitudinal reciprocation thereof to oscillation of the bell crank. Each slide 50 is pivotally connected at 63 to the respective one of the second arms 55 for converting oscillation of the respective bell crank to reciprocation of the slide in outward and inward strokes. A spring 64 is mounted between the end of each second arm 55 and housing 22, as shown in FIG. 2, for biasing the respective bell cranks 52 for rotation in a direction to move the connected slide 50 to a normal position wherein it is located at the limit of its inward stroke.

A feed pawl 66 is pivotally mounted to each of the slides 50 for cooperation with a holding pawl 68 pivotally mounted to the respective carrier 46 for advancing, in conventional manner well known in the art, the respective belt 20 one pitch each reciprocal cycle of the slide and positioning the leading cartridge 18 in the belt at the respective feed throat 69 in housing 22 for pickup by bolt 14 by means of one of two lugs thereon. This is accomplished by having feed pawl 66 engage behind the leading cartridge 18 in the respective cartridge belt 20 and push it inwardly to the related feed throat 69 during the inward stroke of slide 50 and then ride over the next cartridge in the cartridge belt during the outward stroke of the slide with the respective holding pawl 68 engaging a subsequent cartridge in the cartridge belt to prevent the cartridge belt from being drawn outwardly when the feed pawl is disengaged therefrom.

As stated hereinbefore, feed mechanism 16 is adapted to selectively feed cartridges 18 from either of the two cartridge belts 20 by actuation of switch 44. To accomplish this, switch 44 is mounted through an opening 70 in the side of receiver 12 for sliding displacement relative thereto by means of tenons 71 in the front and rear sides of the opening which are received by mortises 72 in the front and rear sides of the switch, as shown in FIG. 6. A pair of balls 74 are spring biased outwardly in switch 44 for releasable engagement with one of three dimples 76 in each of the tenons 71, as shown in FIG. 5, to releasably retain the switch in either an up, neutral or down position. When switch 44 is centered in the neutral position, blade 42 is located so that pins 36 are positioned thereby so that outer ends 62 thereof are free of both channels 58, whereby slides 50 are disconnected from yoke 24 to prevent feeding of ammunition.

To fire cartridges 18 from the bottom one of the cartridge belts 20, with crank in rotation, switch 44 is moved to the down position and thereby the bottom one of the pins 36 is pressed by blade 42 to engage outer end 62 of the pin in the respective channel 58. Thus, slide 50 on the bottom of receiver 12 is connected to yoke 24 for actuation thereby so that feed pawl 66 on such slide feeds the bottom one of the cartridge belts 20 into the receiver and locates the leading cartridge 18 for pickup by bolt 14. As yoke 24 is in continuous reciprocation, blade 42 must, necessarily, be sufficiently long to maintain slidable contact with pins 36 as they are reciprocated by the yoke. When cartridges 18 are to be fired from the top one of the cartridge belts 20, switch 44 is moved to the top position, whereby the bottom one of the feed belts is made inactive through withdrawal of the respective pin 36 from engagement with the bottom bell crank 52 and the top one is activated by engagement of the respective one of such pins in the top one of the bell crank. When switch 44 is moved to the top or bottom position, engagement of outer ends 62 with the respective channels 38 is facilitated by cam surfaces 60 which guide the outer ends thereinto.

It will become obvious to persons skilled in the art that forms other than the embodiment shown and described herein are possible within the spirit and scope of the present invention. Therefore, it is desired that the present invention shall not be limited except insofar as it is made necessary by the prior art and by the spirit of the appended claims.

I claim:

1. In combination with a pair of cartridge belts each comprising a plurality of linked cartridges, an automatic gun including a receiver mounting a feed mechanism for selectively moving either one of said cartridge belts into said receiver, said feed mechanism including a rotary powerinput comprising a crank with a crankpin, a pair of feed pawls each adapted when actuated for moving one of said cartridge belts into said receiver, and means for converting rotation of said power input to translational movement and transmitting the translational movement to a selected one of said feed pawls, said means comprising a Scotch yoke including a crossbar, a pair of bars extending from said crossbar and a slot in said crossbar having engagement with said crankpin to thereby convert rotation of said crank to translation of said Scotch yoke, a pair of slides respectively mounting one of said pair of feed pawls for translational movement, and means for connecting said Scotch yoke to a selected one of said pair of slides for translation thereof.

2. The invention as defined in claim 1 wherein said means for selectively connecting said Scotch yoke to one of said slides comprises a pair of rotatable bell cranks each comprising a first arm and a second arm in angular relationship, means for releasably engaging each of said bars to one of said first arms for converting translation of said Scotch yoke'to rotation of the related one of said bell cranks, and means for selectively engaging each of said second arms to one of said slides for converting rotation of the related one of said bell cranks to translational movement of the respective one of said pair of slides.

3. The invention as defined in claim 2 wherein said means for releasably engaging each of said bars to one of said first arms comprises a pin slidingly disposed through each of said bars, each of said pins including an outer end and a head, a spring disposed between said head of each of said pins and the respective one of said bars for biasing said pins to a position whereby said outer ends are retracted into the respective ones of said bars, a switch disposed for sliding displacement against a selected one of said heads for extending said outer end of the respective one of said pins from the respective one of said bars, and a channel on each of said first arms for receiving said outer end of the respective one of said pins when extended outwardly by said switch for transmitting movement of said Scotch yoke to said bell crank.

4. The invention as defined in claim 3 wherein said switch comprises a blade disposed between said heads for contact thereby responsive to biased displacement of said pins by said springs during reciprocation of said Scotch yoke, and means for slidingly mounting said switch to said receiver for displacement relative thereto between a neutral position wherein said pins are located by said blade in positions whereby said outer ends thereof are free of the respective ones of said channels, a first position wherein one of said pins is positioned by said blade for extension of said outer end thereof into engagement with the respective one of said channels and the other one of said pins is positioned free of the respective one of said channels, and to a second position wherein said other one of said pins is positioned by said blade for extension of said outer end thereof into engagement with the respective one of said channels and said one of said pins is located free of the respective one of said channels.

Claims

1. In combination with a pair of cartridge belts each comprising a plurality of linked cartridges, an automatic gun including a receiver mounting a feed mechanism for selectively moving either one of said cartridge belts into said receiver, said feed mechanism including a rotary power input comprising a crank with a crankpin, a pair of feed pawls each adapted when actuated for moving one of said cartridge belts into said receiver, and means for converting rotation of said power input to translational movement and transmitting the translational movement to a selected one of said feed pawls, said means comprising a Scotch yoke including a crossbar, a pair of bars extending from said crossbar and a slot in said crossbar having engagement with said crankpin to thereby convert rotation of said crank to translation of said Scotch yoke, a pair of slides respectively mounting one of said pair of feed pawls for translational movement, and means for connecting said Scotch yoke to a selected one of said pair of slides for translation thereof.

2. The invention as defined in claim 1 wherein said means for selectively connecting said Scotch yoke to one of said slides comprises a pair of rotatable bell cranks each comprising a first arm and a second arm in angular relationship, means for releasably engaging each of said bars to one of said first arms for convertIng translation of said Scotch yoke to rotation of the related one of said bell cranks, and means for selectively engaging each of said second arms to one of said slides for converting rotation of the related one of said bell cranks to translational movement of the respective one of said pair of slides.