US3136213A - Two-stage tandem type feeding mechanism for firearms - Google Patents

Description

Two-STAGE TANDEM TYPE: FEEDING MECHANISM FOR FIREARMS Filed May 15, 1963 F. P. REED June 9, 1964 4 Sheets-Sheet 1 FIM INVENTOR "Emailen ckR W,

June 9, 1964 F. P. REED 3,136,213

TWO-STAGE TANDEM TYPE F'EEDING MECHANISM FOR FIREARMS Filed May 13, 1965 figli@ 4 Sheets-Shree?I 2 June 9, 1964 TWO-STAGE TANDEM TYPE F'EEDING MECHANISM FOR FIREARMS Filed May 13, 1963 F. P. REED 4 Sheets-Sheet 3 N .im

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1NVENTOR F. P. REED 3,136,213

Two-STAGE TANDEM TYPE FEEDING MECHANISM FOR FIREARMS June 9, 1964 4 Sheets-Sheet 4 Filed May l5, 1963 sav-maf United States Patent O 3,136,213 TWO-STAGE TANDEM TYPE FEEDING MECHANISM FOR FIREARMS Frederick P. Reed, Ludlow, Mass., assignor to the United States of America as represented by the Secretary of the Army Filed May 13, 1963, Ser. No. 280,170 4 Claims. (Cl. 89-33) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to firearms and more particularly to the feeding mechanisms thereof.

In reciprocating bolt type firearms which are fed with cartridges by a linked belt and which utilize a rotary sprocket to advance the belt and successively index the cartridges in a stripping position, the sprocket is conventionally positioned immediately rearward of the barrel chamber and, therefore, at the forward end of bolt travel so that the cartridges may be transferred directly from the retaining links into the chamber.

This design requires an intricate cam arrangement which rotates the sprocket only during a portion of the recoil travel of the bolt, after the bolt passes the sprocket, so as to prevent interference between the bolt and the cartridge belt during advancement thereof. The short feeding time produces rapid acceleration and deceleration of the belt and this causes the belt to whip besides placing excessive strain on the feeding mechanism. Moreover, it is necessary with such design to tilt the cartridge at a sharp angle during stripping so as to align the cartridge with the barrel chamber. This is achieved by either forming the sprocket conically or providing a ramp contactable by the cartridge during stripping. With both designs, the tilting causes a fanning of the links which, in turn, imparts undesirable movement to the belt.

Also, this design requires that the entrance port for the belt and the ejection ports for the stripped links and the fired cases be located in the same section of the receiver which, obviously, reduces the structural strength thereof. Further, when the entrance and ejection ports are all located in the same section, considerable difficulty has been encountered in controlling the stripped links so as not to foulthe feeding mechanism.

These problems have been overcome in the present invention which provides a firing mechanism in which the sprocket is located at the rear end of the firearm receiver away from the ejection port and sufficiently beneath the path of bolt travel so that the sprocket may be rotated during the entire recoil stroke of the bolt without interference therewith. To accomplish this, an elevator is positioned in front of the sprocket and is arranged so that a cartridge may be stripped longitudinally from the sprocket onto the elevator during one cycle of operation and then raised by the elevator into position to be transferred into the barrel chamber during the succeeding cycle.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is alongitudinally cross-sectioned view of a rie showing a feeding mechanism of this invention in battery position;

FIG. 2 is a view taken along line 2-2 of FIG. l;

FIG. 3 is an enlarged View taken along line 3 3 of FIG. 1;

FIG. 4 is an enlarged view taken along line 4-4 of FIG. 1;

3,136,213 Patented June 9, 1964 r ICC FIG. 5 is a reduced view taken along 5-5 of FIG. 4;

FIG. 6 is a view similar to FIG. 5 but showing the bolt assembly in the recoil position;

FIG. 7 is an enlarged view taken along line 7-7 of FIG. 6;

FIG. 8 is a view similar to FIG. 7 but shows the relationship of the sprocket Wheel and pawl during travel of the bolt assembly to battery position; and

FIG. 9 is a view similar to FIG. 1 but with the bolt in recoil position and shows the relationship between the bolt assembly and the cartridges in the sprocket and on the elevator.

Shown in the figures is an automatic rifle 12 having a barrel 14 and a receiver 16 in which a cylindrical bolt assembly 18 is disposed for reciprocation between a recoil position wherein the recoil travel of the bolt assembly is stopped by a buffer 20 and a battery position Wherein the bolt assembly blocks the breech end of the barrel and is releasably locked to the receiver by conventional locking means. Bolt assembly 18 is of conventional twopiece type having a carrier 22 and a bolt 24 which is telescopically disposed therein and is rotated to and from a locking position during relative movement respective to the carrier through cooperating cam means.

Cartridges 26 are fed into receiver 16 by a belt 28 composed of a plurality of links 30 which are held connected by the cartridges so that, when a cartridge is stripped longitudinally from the belt, the stripped link is separated from the remainder of the belt. Belt 28 is advanced into receiver 16 by a feeding mechanism 32 having a housing 34 which is located in receiver 16 so as to be underneath carrier 22 when bolt assembly 18 is in recoil position. A sprocket 36 is rotatingly mounted in housing 34 in an arched recess provided with curved walls 38 which curve upwardly around the sprocket to form a centrally located longitudinal slot 40. An opening 42 in the bottom of the housing provides for vertical passage of belt 28 to sprocket 36 and ejection of the disconnected links 30 therefrom. The paths of movement of belt 28 and the disconnected links 30 are separated by a partition 43. Curved walls 38 guide cartridges 26 in belt 28 to a stripping position in registry with slot 40 and the disconnected links 30 therefrom.

Sprocket 36 is rotated one pitch for each cyclic reciprocation of bolt assembly 18 by a pawl-ratchet device 44 which includes a ratchet wheel 46 fixed to sprocket 36 and a pawl 48 mounted on a beam 50 pivotally mounted on receiver 16 (FIGS, 4, 7, and 8). Pawl 48 is actuated downwardly for displacing ratchet wheel 46 one pitch through the sliding contact of beam 50 by carrier 22 during recoil travel. Beam 50 is actuated upwardly by the camming contact of a lug 52 on carrier 22 with a cooperating lug 54 on the beam during counterrecoil travel of the carrier to the battery position. Beam 50 is designed so as to be progressively depressed downwardly by carrier 22 during the entire recoil travel thereof to provide smooth advancement of belt 28. Positioned forwardly of housing 34 in receiver 16 is an elevator 56 which consists of a casing 58 in which a platform 60 is biased upwardly by a cooperating spring 62. A pair of arcuate lips 64, similar to the lips in a conventional boxtype magazine, curve upwardly and inwardly from opposite sides of casing 58 and a portion of the rear end of the casing is cut out at 66 to provide clearance for the longitudinal movement of cartridge 26 onto platform 60 from sprocket 36. A ramp 68 on the rear end of platform 60 is arranged for contact by cartridge 26 during stripping which contact causes downward displacement of the platform to a depressed position. Elevator 56 is pivotally mounted on receiver 16 at 70 so that firearm 12 may be cleared by pivoting the elevator downin belt 28 is advancedL to the Vstripping position.

wardly which displaces cartridge 26 in the elevator away from contact by bolt 2d. y v t A Cartridges 26 are stripped forwardly frombelt 28 onto platform 56 bya feed pawl '72 lwhich is mounted on the underside of carrier 22 lat the rear end thereof so as to extend downwardly through slot 40. Lips 64 are desaaie signed so that, when a cartridge 26 is pushed upwardly Operation Whenv a cartridge 26 is red in barrel 14 and bolt asthereagainst by platform l60,'a section ofthe cartridge i bolt Vreciprocal therein between a battery 4and ya recoil position, a feeding'rnechanism having a rotary sprocket disposed for successively advancinga cartridge in a .belt of disconnectable links to a'fstripping position under the bolt ,when in the recoil'position, a feed pawl mounted on vthe rear end ofthe bolt for stripping the cartridge longitudinallyY forward frorn'thevr belt during one cyclic reciprocation of the bolt, an'elevator arranged to receive the stripped cartridge from the belt and to elevate the 'I cartridge into a position for contact byfa'headon the bolt during the succeeding cyclic reciprocation` to chamber the cartridge inlthe barrel,-anda housingfor supporting` saidy sprocket, curvedportionsl extendingup- Y wardly vand inwardly from opposite sidesV of said housing ping position and the disconnectedlinks Vofthe belt therearoundV said'sprocket to guide the cartridges tothe stripfrom, VapartitionV Varranged in said housing to provide sembly 18 is energized for recoil flight by a conventional operating mechanism (not shown),A carrier 212 moves rearwardly to gradually depress. beam i) and rotate sprocket 36 vone pitch, whereby the leading cartridge As sprocket 36 is rotated,^link 39, disconnected from belt 2S during the previous operatingV cycle of rifle 12, is

moved around in itsY path of ejection guided by the cor# responding one of the'curved walls 3S to preventinterference between the link and feeding mechanism* 32. DuringV the initial portion of the recoil travel ofV bolt assembly* 18, cartridge V26 in elevator 56 is held depressed by slidingcontactof carrier 22. Before carrier l22 loses contact with cartridge 26 in elevator 56, head 74, which has the sarnediameterv as carrier 22, makes contact with kthe cartridge to hold it depressed during continued recoil travel of bolt assembly 18. .Before bolt assembly 18 Y reaches recoil position, head 74 moves away from. contact with cartridge 26 in elevator 56, permitting the cartridge to be' lifted by spring-biased platform 60 into `contact with the lips 64 ready Vfor pick upbyV head 74 dur-V ingL counterrecoil travel of bolt assembly 18.

When bolt assembly 18 is stopped in recoil' position by buffer 20 and then proceeds to `battery position, head 74` contacts the base of cartridge 26 in elevator 56 to initiate the transfer of the cartridge Vtowards the chamber of barrel 14. Feed pawl 72 then makes contact with the base of cartridge 26 indexed by sprocket 36 in the strippingposition. Continued movement of bolt assembly 18 to Abattery position simultaneously moves cartridge 26 fromrelevator 56 into the chamber of barrel 14 and the stripping position cartridge from sprocket 36 i into the elevator when the other vcartridge is cleared therefrom.

Although a particular embodiment of -the invention has vertical passage of the belt to said sprocket and the links therefrom, and Va longitudinal 'slot formed between said curved Vportions Yto permit extensionfofV saidfeed pawl therethrough for stripping the` cartridge fromV the belt.

`. 2j The feeding mechanismV as dened infclairn l and including a l'beam pivotally mounted on the receiver for.

' cammingcontaet by-the boltduringdisplacement from" the battery to the recoil 'position andjso asto be progres-VVV sively'depressed bylthe boltduring the entire'travel'therer of to the recoilposition, a ratchet wheel flXed'to said Y sprocket, a pawl operationally disposed between said beam and saidratchet wheelfor converting depression of said beam to rotational displacement of said ratchet wheel foradvancing the beltone pitch, anda cam lugony said beam arranged for contactwitha cooperating cam lugV i Von said boltduring travel thereof Vto the for displacing said beam upwardly. A y

3. The feeding mechanism asdened in'claim 1 wherein said elevator includes a casing, a platform spring-biased Y upwardly` in saidV casing and` arranged tokk receive the cartridgeV from said sprocket, means for displacing said platform downwardly when the cartridge is moved longi-y tudinally forward thereonto from said'sprocket, and a. pair of Vlips formed on said casing for limiting upward displacement of the cartridge by said'fplatform and positioning the cartridge thereon for contactual pickup by said head.

4. The feeding mechanism asV defined in c'laim'3where-V in the bolt is arranged t0 have contact with the cartridge during/*displacement thereof from said sprocket to-said elevator so as to provide longitudinal displacement of the.L cartridge, and'wherein said means for ffdisplacing said' platform downwardly comprisesa rampforlned onone v end'of jsaid platform forv camming contactby'the car-` tridge when moved thereon.

been described in detail herein,rit is evident that many 'References Cited inthe le ofV this patentf -r Y UNTTED STATES PATENTS i i 544,657 f Browning Q.' Aug. 20,V 1895 2,388,291 Y Ruger r- Nqv.6, 194s battery position i

Claims (1)

1. IN A FIREARM HAVING A BARREL AND A RECEIVER WITH A BOLT RECIPROCAL THEREIN BETWEEN A BATTERY AND A RECOIL POSITION, A FEEDING MECHANISM HAVING A ROTARY SPROCKET DISPOSED FOR SUCCESSIVELY ADVANCING A CARTRIDGE IN A BELT OF DISCONNECTABLE LINKS TO A STRIPPING POSITION UNDER THE BOLT WHEN IN THE RECOIL POSITION, A FEED PAWL MOUNTED ON THE REAR END OF THE BOLT FOR STRIPPING THE CARTRIDGE LONGITUDINALLY FORWARD FROM THE BELT DURING ONE CYCLIC RECIPROCATION OF THE BOLT, AN ELEVATOR ARRANGED TO RECEIVE THE STRIPPED CARTRIDGE FROM THE BELT AND TO ELEVATE THE CARTRIDGE INTO A POSITION FOR CONTACT BY A HEAD ON THE BOLT DURING THE SUCCEEDING CYCLIC RECIPROCATION TO CHAMBER THE CARTRIDGE IN THE BARREL, AND A HOUSING FOR SUPPORTING SAID SPROCKET, CURVED PORTIONS EXTENDING UPWARDLY AND INWARDLY FROM OPPOSITE SIDES OF SAID HOUSING AROUND SAID SPROCKET TO GUIDE THE CARTRIDGES TO THE STRIPPING POSITION AND THE DISCONNECTED LINKS OF THE BELT THEREFROM, A PARTITION ARRANGED IN SAID HOUSING TO PROVIDE VERTICAL PASSAGE OF THE BELT TO SAID SPROCKET AND THE LINKS THEREFROM, AND A LONGITUDINAL SLOT FORMED BETWEEN SAID CURVED PORTIONS TO PERMIT EXTENSION OF SAID FEED PAWL THERETHROUGH FOR STRIPPING THE CARTRIDGE FROM THE BELT.

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