[1]U-ni'ted States Pateiit Office 219932414 2,993,414 AMMUNMON FEED MECHANISM Charles K. Woodman, Beverly, Mass., assignor to United Shoe Machinery Corporation, Flemington, N.J., a corporation of New Jersey Filed June 5, 1946, Ser. No. 674,542 8 Claims. (Cl. 89-53) This inventi(yn relates to means; for supplying arnmunition to automatic guns, such as those used in aircraft, fr<)m a linked belt and is particularly,concl-med with an :autornatic feed mechanism mounted on a gun. An object of the invention is to increase the belt pu'iling capacity of such feed mechanisms, particularly their ability to lift a lon- belt, and to insure sim-ultaneously ,a delivery o-f successive cartridges frorn the belt to the breech mech-anism without reducing the finng rate of the gun. Another object of t-he invention is to reduce the ,overall dimensions of such feed mechanisms so, that they can be used @readily and effectively within a confin--d space sueb as in the win.-s of aircraft. The links forrning an ammunition belt have a ring portion which embrlces slightly more than half the circumference of the large case porti<),n of a cartridge. It has been customary, heretofore, in feed merhan@isms for 20 mm. guns, to n-io,@e the cartridges axially until their reduced portions rearh the rings and then to effect repioval of the links. The released cart@ridges drop into the path , of the breech bolt. The feed mechanism of the present invention removes the cartridges from the links diame,trically, feeds them into the breech mechanism, and holds them firmly in position to be picked up by the breech bolt. This @elirninates the space consuming mechanism for axial displacement of the cartridges and insures control (ver each cartridge until it is chambered. Accordi@ngly, Dne feature of.the, invention provides an anitnunition feed mechanism in which the leading ca-rtridges fed into the mechanism in a t@elt are engaged above the feeder mouth of the mechanism -and stripped ,from the belt by a vertioally movable member. Another feature of the invention provides vertical feed members which assume control of the stripped cartridge and hold it in posit-ion to be picked up by the breech bolt of t@he gun. T,be invention also provides novel means for act-Liating the stripping and vertical feed members as weU as a cgntrol for terminating the horizontal feed when the last cartridge in the belt passes beyond the horizontal feed means. In the acco-nipanying drawings, FIG. 1 is an angular front view of a right hand feed mechanism mounted on a gLin; FIG. 2 shows the fee-d mechanism opened up to reveal features of its intemal structure; FIG. 3 is a left hand side view of the -feed -mechanism, partly in section, showing the leading round in the belt in posit@ion to@ be stripped f@rom the belt; FIG. 4 is a fragmentary view showin-g the leadin.a ro,und stripped f@rom the belt; FIG. 5 is an -angular view of the stripper and the vertical feed units, seen from the back of the -feed mechanism; FIG. 6 is an angular view of a release mechanism on t-he gun; FIG. 7 is a view of the release mechanism, partly in section, on line VII-VII of FIG. 6; FIG. 8 is a section on line VII-VII of FIG. 7; FIG. 9 is a rear view of a cam bar cooperating with the release mechanism shown in @F-IGS. 6 and 7; @FIG. 110 is a partial view, similar to FIG. 71 showing i-he parts of the -release mechanism in a different position; Patented July 25, 1961 2 FIG. I 1 is a rear view of a modffied form of release mechanism; Fl--. 12 is a section on lilae 3al-XII of FIG. II; and Fj'LG. 13 is a detail view of a safety switch for control'ling the feed motor, with the switch operating plate in raised position. General ilhe -feed mechanism for providing a -gun with am-muni10 tio-a comprises a small, compact frame 10 (FIG. 1) containing a horizontal feed unit, a stripper unit, and a vertical feed unit wech cooperate to bring successive, rounds or cartridges from an ammunit@ion belt, by means of which the rounds are supplied to the feed mechanism, into the path of the reciprocating igun breech bolt in -a man15 -ner to be described. The gun-, as illustrated, is a 20 mm. aircraft gun. The belt, i C., the linked rounds, enters the f-rame tlhough an -ammunition mouth 12 at the front, of the frame and moves along a slightly upward inclined 20 path over a g,uard 14 to the upper end of a feeder mouth 16 (FIGS. 2 and 3) formed by downward projectin-g walls of @the frame. The feeder mouth eng -- ages in the breech bolt passageway of the gun and has lips 17 for suppor@ting Tounds in the path of the breech bolt. As the rounds move ttirough the feed mechanism in 25 their substantially horiz(>ntal ath, upward displacement p of the rounds is prevented by a cover,18 (FIG. 3) which is pivoted to -the back of the frame 10 by pins 20. The cover is held in closed position by a spring pressed latiz@h 30 22 engaging a projectio-n 24 on the frame portion surroundingthe ammunition mouth 12. Thefeed mechanism is secured to a magazine slide 26 (FIGS. I and 3) by means of screws. This slide is, similar to the slides ordinarily mounted in the receiver bodies 35 of guns of the present type and remains stationary during the firiiig of the gun, permitting movement of the gun -relatively thereto during recoil and counterrecoil. Horizontal feed unit A motor 28 (FIG. 1) fumishes the force for lifting 40 the belt and moving it horizontally through the feed mechanism i to position above the feeder mouth. The motor is secunred to,a gear box 30 attached -toi the frame 10 and contairung a non-reversing reduction gear mech45 anism (not shown). The input of the motor into the reduction gear mechanism is at 2000 r.p.m.; the output speed of t-he reduction gear mechanism is 130 r.p.m. The reduct-ion gear mechanism rotates a @feed shaft 32 (FIG. ?) @mounted in the frame 10. Surrounding the feed 50 shaft is a sprocket tube 34, one end of which rotates about a collar (not shown) on the @feed shaft 32 and the other end of which rotates in bearings in a sprockett@ube,,hous:ng 36 secured to the frame 10. Mounted within the, sprocket tube and surrounding the feed shaft is a tor55 sion spring 38, one end of which is joined to the shaft coflar referred to above and the other end of which is secured in an opening in the breech end of @the sprocket tube. The spring 38 is wound by the motor to impart ro-tation to the sprocket tube aiad @thus to feed the am60 munition bolt horizontally by means of two sprockets 40 which are forined on the tube and enga-ge successive rounds in the bfflt (see FIG. 3). Stripper unit 65 As successive rounds are m(>ved into position above the feeder mouth 16, they engage a stripper 42 (FIG. 5) mounted for vertical movement in guideways 44 of a member 46 forming the rear wall of the feed mechanism. The stripper 42, as showia in FIG. 5, has two projections, 70 which are spaced apart approximately the width of a link and the inner faces of which are r(yunded to conform to the curvature of the rounds so that each round is &ml I y
[2]3 engaied by the stripper as it reaches its position above the feeder mouth. At this thne the Hnks engaging a round above the feeder mouth rest ori ledges 48 (FIG. 3) formed at the inner ends of the guard 14 and on a link plate 50 mounted in an opening of the wall 46 thus suPporting the round in position to be stripped. When the stripper 42 is actuated to strip a round from the links, as will be described below, the link plate 50 may yield outward from its link supporting position against the pressure of a spring 52 to permit downward movement of the round. The pressure of the spring 52 may be adjusted by means of a screw 54. Vertical feed unit Two feed fingers 56 (FIG. 5) serve to move the stripped rounds downward in the feeder mouth into position to be picked up by the breech bolt. The fingers 56 are pivotally secured to slides 60 by pins 58. The slides 60 are verticary movable iii guideways 62 formed in the wall 46. Means for imparting upward and downward movement to the slides are mounted in housin,-s formed in the wall 46 back of the guideways 62, the tops of the housings being closed by a front cover 64 (FIG. 2) and a rear cover 66 secured to the wall 46. The means for moving the slides 60 include bell crank levers 68 mounted to swing about pins 70 (FIGS. 2 and 5) secured to the wall 46 by screws 72 (FIG. 2). An arm 73 (FIG. 5) of each bell crank lever 69 fits into an opening formed in a curved projection 74 on the back of each slide 60. Counterclockwise movement of the bell crank levers 68, as seen in FIG. 5, by means to be described below, raises the slides 60 and fingers 56. Downward movement is imparted to the slides in the foffowing manner. A torsion spring 76 surrounds the pin 70 of the front bell crank lever 68, one end of the spring 76 being connected to the bell crank lever and the other to the pin. Acting on the rear slide 60 is a compression spring 78 which is mounted in a housing 80 (FIG. 2) integral with the rear cover 66 and which engages the upper face of the rear slide 60. The springs 76, 78 are energized by the counterclockwise movement (FIG. 5) of the bell crank levers 68 and upon release of the bell crank levers assume control of the slides 60 to impart downfeed movement to the slides. The forward ends of the feed fingers 56 are normally held in position to engage the top of a round, as shown in FIGS. 3 and 4, by means of springs 82 connected to pins 84 in the flngers 56 and to hooks 86 on. the projections 74 of the shdes 60. The springs 82 permit the fingers to yield inward and downward as a round passes the fingers during its downward movement out of engagement with the belt, at which time the slides 60 are moving upward. When the round has passed the fingers, the springs 82 immediately move the ends of the fingers outward into round engaging position in preparation for the downward feed. The stripping and vertical feed units may be actuated by either of two altemative forms of actuating means, the first, and preferred form, being shown in FIGS. 2, 6, 7, 8, 9 and 10 and the second, alternative, form being shown in FIGS. 4, 5, 11 and 12. These two forms of actuating means will now be described separately. Actuating means (modification 1) for stripping aiid vertical feed units The stripper 42 is moved up and down by means of a cam bar 88 (FIG. 2) mounted in ways 90 (FIG. 6) of the magazine slide 26. The cam bar has formed therein two cam tracks 92 (FIG. 9) in which pins 94 projecting from the back face of the stripper 42 engage. T'he cam bar 88 is moved longitudinally, widthwise of the feed mechanism, by means of a rod 96, a hook 98 on the rear portion of_ the cam bar 88 engaging in a notch ILOO (FIG. 6) formed in e forward end of the rod 96. 2,993,414 4 sion plate 102 of the frame 10. The rod portion extending rearward beyond the plate 102 is joined to a release mechanism 104 (FIGS. 6 and 7) carried by a bracket 106 secured to the gun. Thus, the rod participates in the recoil movement of the gun. In order more clearly to understand the actuation of the stripper and the vertical feed units, the release mechanism will first be described. The rod 96 extends through a rod guide 108, the forward end of which is threaded 10 into a socket provided in the plate 102 (FIG. 7). Adjacent to the rod guide 108 the rear end of the rod 96 is surrounded by a cage 110 containing six balls 112 (FIGS. 7 and 8). The diameters of the balls exceed the thickness of the cage in which they are mounted so that the 15 balls engage in a depression 114 (FIG. 7) of the rod 96 thus coupling the rod to the cage. Mounted on the forward end of the cage 110 is a sleeve 116 which maintains the balls 112, in the cage. An inward extending radial projection on the front end of the sleeve 116 engages an 20 outward extending radial projection on the rear end of the rod guide @109. The cage is joined to the bracket 106 by links 1:22 each secured at one end to the bracket 106 and at its other end to the cage 110 (FIG. 6). In addition, an annular portion 124 formed on the bracket 106 25 and surrounding the cage 110 abuts a projection 126 on the cage. The cage will thus participate in the movements of the bracket 106, and the gun to which it is secured during recoil and counteffecoil. During the recoil movement of the gun parts, the an30 nular portion 124 of the bracket 106 will force the cage 110 iearward. 'fhe balls 112 at first move along the inner face of the sleeve 116 held against movement by the rod guide 108. After five-eighths of an inch of recoil the balls are moved into a position opposite a space 35 128 (FIG. 10) formed by an enlarged portion at the rear end of the sleeve and opened by the recoil movement of the cage. At this time a preloaded spring 130, the forward end of which abuts an annular portion 132 on the rod 96 and the rear end of which abuts a plug 134 40 threaded into the end of the cage, forces the balls out of the depression 114 in the rod 96 and upward into the space 128, as shown in FIG. 10, thereby releasing the rod 96 which is then moved forward by the spring 130. The cage 110 continues its rearward rnovement with the 45 recoiling gun, the balls now moving along the inner face of the enlarged portion of the sleeve 116. During the counterrecoil movement of the gun the cage is moved forward with the gun parts by the links 122. The rod 96 is stationary at this time, having completed 5o its forward or return movement to its initial position. Thus the counterrecoil movement of the cage 110 relatively to the rod 96 will load the spring 130 in preparation for imparting forward movement to the rod during the next recoil movement of the gun. When the balls 55 112 reach their position of engagement with the inchned face formed by the inner end of the sleeve enlargement (FIG. 10) they move the sleeve 116 forward relatively to the rod guide 108. This movement of the sleeve compresses a spring 136 which surrounds the rod guide 108 6o between the sleeve and the plate 102. As the balls 112 again reach their position above the depression 114 of the rod 96 the spring 136 has been compressed sufficiently to prevent continued forward movement of the sleeve 116 and the balls are forced downward back into the 65 depression 114, again coupling the rod 96 and the cage 110. The spring 136 then moves the sleeve 116 reanvard to its initial position shown in FIG. 7. The force of the spring 136 may be vziried by two collars 138 threaded onto the rod guide 108. 7o The stripper and vertical feed units are actuated in the following manner. The recoiling cage 110, through the balls 112, moves the rod 96 accordingly, the rod carrying the- cam bar 88 with it. During the rearward movement of cam ar 8 pins 94 of t stripper -The forward end of the rod 96 is mounted in an exten7,5 42 will move downward in the cam tracks 92 of the bar
[3]9,998,4i4 5 88 and the stripper 42 will be moved downward, moving a round out of engagement with the belt. While moving rearward with the rod 96, the cam bar 88 simultaneously rotates the bell crank levers 68 in counterclockwise direction as seen in FIG. 5, a projection 140 (FIG. 9) on the 5 front end of the cam bar 88 engaging one arm of the front bell crank lever 68 and the rear edge 141 of the bar engaging one arm of the rear bell crank. Counterclockwise movement of the bell crank levers 68 moves the sedes 60 upward in preparation for their feed move- 10 ment, and simultaneously compresses the spring 78 aiad winds the spring 76. Forward or reverse movement of the rod 96, occurring after five-eighths of an inch of recoil, release the bell cranks 68, permittin- the springs 76, 78 to impart downward feed movement to the feed 15 fingers 56. At the same tiine the stripper 42 will be moved upward by the upwaxd movement of the stripper pins 94 in the cam tracks 92. Actuating means (modification 2) for stripping and v,@rtical feed units 20 A modified type of actuating means for the stripper and the slides 60 may be tised in place of that described above. In includes a stripper cam bar 142 (FIG. 5) siinilar to the bar 83 and mounted for movement width- 25 wise of the feed mechanism in guideways of the magazine slide 26. The stripper cam bar 142 is also provided with two cam tracks 144, like the cam tracks 92, in which the pins 94 on the stripper 42 engage. In accordance with the modification, a separate finger operating slide 146 is 30 provided for moving the feed shdes 60 upward and for energizing the springs 76, 78. The finger operating sede 146 is mounted for movement in the magazine slide 26 back of the stripper cam bar 142, the rear edge of the slide engaging the left arm (FIG. 5) of the rear bell 35 crank lever 68 and a projection 151 on the front end of the slide engaging the left arm of the front beR crank 66. To guide the finger operating slide 146 during its movement with, as well as during its movement relatively to, the strippor cam bar 142, a dowel 148 on the stripper 40 cam bar moves in a longitudinal slot 150 (FIG. 11) of the finger operating slide. The bar 142 and slide 146 .may be adjusted relatively to each other by a screw (not shown). The cam bar '142 and the slide 146 are coupled f6r 45 movement as a unit by means of a ball 152 (FIG. 11) seated in a cage 154 mounted for rotation in an opening of the stripper cam bar. The diameter of the ball 152 is greater than the width of the stripper cam bar opening and projects beyond said opening into a socket or depres- 50 sion 158 (FIG. 12) of the fin,-er operating slide 146. ne ball 152 is normary held in its upper position shown in FIG. 1 1 by means of a spring 160 which engages a face 161 on the cage 154. The spring 160 is partially mounted on a pin 162 positioned in a slot extending from 55 the cage opening, the free end of the spring - projecting into the opening to engage the cage. The stripper cam bar 142 is reciprocated by a rod 164, a projection 166 (FIG. 5) on the rear end of the bar 14Z engaging in a notch in the rod 164. The Tod 164 is 60 mounted for movement in the frame 10 and projects beyond the frame where it is secured to the recoiling gun parts (not shown). As the rod 164 moves rearward during recoil it moves the stripper cam bar 142 accordingly. The pins 94 move along the tracks 144 to lower 65 the stripper 42, disengaging a round from the belt. Since the finger operating slide 146 is coupled to the bar '142, it also participates in the movement of the rod 164, swinging the bell crank levers 68 in c ounterclockwise direction, as seen in FIG. 5, to move the slides 60 upward 70 and energize the springs 76, 78 ' Mounted in a longitudinal slot in the magazine shde 26, back of the finger operating shde 146 is a compression spring 168 the rear portion of which is supported by a guide pin 169 also seated in the slot. The front end of 75 the spring 168 abuts a proi - ection 170 on the slide 146, the projection compressing the spring 168 during its recoil movement. After five-eighths of an inch of recoil, the spring 168 has acquired sufficient force to counteract the rearward movement of the finger operating slide 146 and thus to force the ball 152 out of the depression 158 and into the upper path of a track 172 (FIGS. I 1 and 12) formed in a guide piece 174 which is secured to the wall 46 adjacent to the stripper cam bar 142. This disengages the sude 146 from the stripper cam bar 142. The spring 168 then moves the released finger operating slide 146 in reverse direction back to its initial position permitting the springs 76, 78 to impart downward feed movement to the slides 60 and thus to the feed fingers 56. In this form of the invention, the stripper cam bar 142 and the rod 164 continue their rearward movement with the recoiling gun parts, the ball 152 now moving in the upper path of the track 172i During the counterrecoil the rod 164 moves the stripper cam bar 142 in reverse direction, again raising the stripper 42. As the ball 152 moves alona the downward inclined path of the track 172, it rotates the ca@e 154 clockwise (FIG. 11) compressing the spring 160 When the ball reaches its position in the lower path of the track 1172, the stripper cam bar has again reached its initial position relatively to the finger operating slide 146 and the ball is opposite the depression 158. The spring 160, sufficiently compressed by the ball 152, then forces the ball 152 out of the track 172 and back into the depression 158, simultaneously rotating the cage 154 counterclockwise (FIG. 1 1) so that the ball resumes its position shown in FIG. I I in the upper end of thedepression 158, again coupling the bar 142 a-@id slide 146. Sprocket locking slide In both r@iodifications the horizontal feed of the ammunition belt by the spr6ckets 40 is periodically limited by an escapement slide 176 (FIGS. 3 and 5) mounted to reciprocate in the frame 10, the inner end 178 of the slide projectitig into the feeder mouth upon inward movement of the slide. Joined to the outer end of the slide 176 adjacent to the sprocket tube 34 is a lever 180@ which fulcrums about the edge of an opening in the frame 10, the lower end of the lever 180 passing through the opening. A spring 182 (FIG. 3) one end of which is attached to the lever 180 and the other etid of which is joined to the frame 10 tends to draw the escapement slide toward the sprocket tube. Whelq the sprockets,40 are rotated to feed the belt, they engage cam faces 184 formed on the outer end of the escapement slide 176 and move the slide inward against the action of the spring so that the sprockets can pass the slide. The inner end 178 of the escapement slide extelids into the feeder mouth, i.e., into a vacancy in the path of the cartridges, at th;s time. However, when the breech bolt is recoiling, the loose rounds in the feeder mouth are in the path of mcvvement of the escapement slide 176 and thus prevent movement of the slide toward the 4Leeder mouth by the sprockets 40, lockin.- the sprockets temporarily against rotation until the loose rounds have be,-n fed downward. The horizontal component of the sprocket force at this time is exerted against the side of the round in the path of the escapement slide and the vertical compolient of the sprocket force is exerted against the escapement slide itself. Since the direction of the sprocket force is substantially downward, most of the force is taken up by the escapement slida and not transmitted to lips 17 of the feeder moi-ith, thereby safeguarding the lips and permitting th-- breech bolt to recoil without too much resistance. When the breech bolt has passed to the rear of the loose rounds and while it is moving forward in counterrecoil, the vertical feed fingers 56 move the loose roupds down@,vard out of the path of theescapement slide. The sprockets 40 are then released and resume the cross@feed of the belt.
