Low inertia linear linkless ammunition feeding system

A linear linkless ammunition feeding system includes a magazine in which a major portion of an endless ammunition conveyor is supported in serpentine formation on upper and lower sets of opposed rails. Screw feeder elements convey this serpentine formation linearly to an exit end of the magazine where the serpentine conveyor loops thereof are successively unwrapped from the rails by a first shuttle mechanism and accelerated to conveyor gun firing velocity. A second, identical shuttle mechanism stationed at the entrance end of the magazine decelerates the conveyor coming from the gun and wraps it into serpentine loops on the rails.

The present invention relates to a system for dispensing articles from 
storage at high velocities and is specifically directed to feeding 
linkless rounds of ammunition from a magazine to a machine gun or cannon 
at a rapid firing rate. 
BACKGROUND OF THE INVENTION 
In the typical linear linkless ammunition feeding system, the individual 
rounds of ammunition are accommodated in separate carriers which are 
serially interconnected to form a conveyor. This conveyor is trained 
throughout the interior of the magazine in a manner to maximize packing 
density and exits the magazine to deliver the rounds seriatim to the gun. 
At some point in this delivery, the rounds are picked from the conveyor 
carriers and loaded into the gun for firing. In many gun system 
applications, it is required that the spent shell casings be saved rather 
than simply ejected from the system. In such case, the conveyor is 
typically made endless, and the spent shell casings are successively 
returned to the carriers of the conveyor for conveyance back into the 
magazine and stored. 
An ammunition handling system of this linear linkless type is disclosed in 
Stoner U.S. Pat. No. 4,573,395, wherein an endless ammunition conveyor is 
trained in a serpentine or folded accordian path through a magazine. The 
conveyor exits the magazine at one end to deliver live rounds to a 
rapid-fire gun and re-enters the magazine at the other end carrying spent 
rounds for storage. It will be appreciated that, in systems of the type 
disclosed in this patent, the entire conveyor must be driven at a 
requisite high velocity to satisfy the rapid firing rate of modern gun 
systems. This requires a large and powerful conveyor driving source, 
particularly where large ammunition is concerned. In addition, the power 
source must possess the further capacity to rapidly accelerate the entire 
conveyor and its ammunition cargo from a standing start to the full gun 
firing rate velocity. A magazine fully loaded with live rounds represents 
considerable inertia to be overcome during such rapid acceleration. 
To reduce the requisite conveyor velocity without prejudicing gun firing 
rate, resort has made to a two-bay or two-tier conveyor arrangement 
wherein the rounds of ammunition are conveyed to the gun in pairs. This 
approach theoretically reduces the conveyor speed by one-half relative to 
a given gun firing rate, but adds the complexity and cost of a merging 
mechanism for picking off each round of the pair for successive delivery 
to the gun. This merging mechanism also represents and additional source 
of power consumption. The linear linkless ammunition feeding system 
disclosed in Bacon et al. U.S. Pat. No. 4,424,735 is representative of 
this "tiered" feeding approach. 
Another approach to reducing the velocity of the bulk of the ammunition 
feeding motion is disclosed in Darnall U.S. Pat. No. 4,433,609. In this 
system, an ammunition round carrying conveyor is suspended at spaced 
points along its length from elevated, opposed side rails, such that the 
intervening segments of the conveyor hang loosely and uncontrollably from 
the suspension points as depending loops or pleats. As the gun fires, the 
conveyor loop segments are successively drawn off the exit ends of the 
side rails and thus freed for the delivery of rounds to the gun. Thus, 
only the freed conveyor loop segments travel at the high velocity to 
satisfy a rapid firing rate, while the suspended conveyor loop segments 
traverse the magazine toward the exit ends of the side rails at a 
significantly reduced velocity. The ammunition conveyor of this Darnall 
patent is open ended and thus cannot return fired shell casings to the 
magazine for storage. Moreover, loading the magazine with live rounds is 
strictly a time-consuming manual procedure. 
It is accordingly an object of the present invention to provide an improved 
ammunition feeding system. 
A further object is to provide an ammunition feeding system of the 
above-character which is capable of accommodating rapid gun firing rates. 
Another object is to provide a linear linkless ammunition feeding system of 
the above-character wherein motive power requirements are dramatically 
reduced. 
A still further object is to provide a linear linkless ammunition feeding 
system of the above-character, wherein the inertial load resisting the 
rapid acceleration of the feeding system to full gun firing rate is 
significantly reduced. 
An additional object is to provide a linear linkless ammunition feeding 
system of the above-character which not only conveys live ammunition 
rounds from a magazine to a gun, but conveys spent shell casings back to 
the magazine for storage. 
Yet another object is to provide a linear linkless ammunition feeding 
system of the above-character wherein the storage of live ammunition 
rounds and spent shell casings within the magazine is effectively 
controlled. 
A further object is to provide a linear linkless ammunition system of the 
above-character which is economical in construction, efficient in 
operation, and reliable over a long useful life. 
Other objects of the invention will in part be obvious and in part appear 
hereinafter. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there is provided an ammunition 
feeding system of the linear linkless type comprising a magazine through 
which is trained in serpentine formation an endless conveyor equipped with 
ammunition round-accommodating carriers uniformly distributed along its 
length. This ammunition conveyor emerges through an exit in the magazine 
to successively deliver live ammunition rounds to a rapid-fire gun and 
successively accepts in exchange spent shell casings for conveyance back 
into the magazine through an entry thereof. 
The magazine is equipped with sets of opposed, linear rails for supporting 
at spaced intervals each of the depending serpentine loops of that portion 
of the ammunition conveyor arranged in serpentine formation within the 
magazine. A first, reciprocating shuttle mechanism, stationed at the exit 
of the magazine, includes cooperating sets of drive sprockets operating to 
successively unwrap serpentine conveyor loops from their supporting rails 
and accelerate them to conveyor rapid gun-firing velocity. A second, 
reciprocating shuttle mechanism, stationed at the entry of the magazine, 
includes cooperating sets of drive sprockets operating to decelerate the 
returning ammunition conveyor from gun-firing velocity and wrap it as 
serpentine conveyor loops on the supporting rails. 
The reciprocations and sprocket speeds of the first, unwrapping shuttle 
mechanism and the second, wrapping shuttle mechanism are coordinated for 
smooth ammunition feeding operation. In addition, a secondary conveyor, 
driven in coordination with the shuttle mechanisms, linearly conveys the 
serpentine formation portion of the ammunition conveyor en masse from the 
wrapping shuttle mechanism to the unwrapping shuttle mechanism at an 
appropriate velocity dramatically less than conveyor gun-firing velocity. 
The invention accordingly comprises the features of construction, 
combination of elements and arrangement of parts, all of which will be 
exemplified in the construction hereinafter set forth, and the scope of 
the invention will be indicated in the claims.

DETAILED DESCRIPTION 
The linear linkless ammunition system, generally indicated at 10 in FIG. 3, 
includes a magazine generally indicated at 12, whose overall construction 
can best be appreciated from FIG. 1. As seen therein, the magazine 
includes a front wall 14 and a back wall 16 which are maintained in 
spaced, parallel relation by a multiplicity of tie rods 18. Mounted to the 
interior sides of the front and back walls in opposed relation are upper, 
intermediate and lower parallel sets of linear rails, generally indicated 
at 20, 22, and 24 respectively. Only the back wall rail sets can be seen 
in FIG. 1, and their full longitudinal extend can be appreciated from FIG. 
3. Each upper rail set 20 includes four coextensive, vertically spaced, 
parallel rails 20a, 20b, 20c and 20d; each intermediate rail set 22 
includes two coextensive, vertically spaced, parallel rails 22a and 22b; 
and each lower rail set 24 includes four coextensive, vertically spaced, 
parallel rails 24a, 24b, 24c and 24d. 
As seen in FIG. 3, these opposed rail sets serve to support within the 
confines of magazine 12 a major segment of an endless ammunition conveyor, 
generally indicated at 26, in a serpentine formation, generally indicated 
at 26a. This ammunition conveyor may be and preferably is of the type 
disclosed in the commonly assigned Wetzel et al. U.S. Pat. No. 4,166,408, 
the disclosure of which is specifically incorporated herein by reference. 
Thus, conveyor 26 is comprised of an endless series of pivotably 
interconnected cradles or carriers, several being illustrated at 28 in 
FIG. 1, each accommodating a single round of ammunition, not shown. Each 
carrier is equipped with resilient means (not shown) for securely 
retaining the ammunition round until it arrives at a suitable 
stripper-feeder, generally indicated at 30 in FIG. 3, which is stationed 
proximate a pair of idler sprocket sets 31 rotatably mounted by the front 
and back magazine walls. The stripper-feeder successively picks the 
ammunition rounds from the arriving carriers for conveyance to rapid-fire 
gun 30a and successively deposits fired shell casings into the departing, 
just emptied carriers. It is understood that the stripper-feeder and 
rapid-fire gun are not material to the present invention and have been 
omitted from the text and drawings in the sake of brevity. 
Rotatably mounted at each end of each carrier is a roller 28a (FIGS. 1 and 
3) by which the ammunition conveyor is supported by the front and back 
wall rail sets in serpentine formation 26a. Thus, as seen in FIG. 3, three 
consecutive opposed carrier rollers 28a are captured between rails 20c and 
20d and between rails 20a and 20b of opposed upper rail sets 20 to provide 
support and longitudinal guidance for each upper fold or turnaround of the 
conveyor serpentine loops comprising formation 26a. Similarly, three 
consecutive opposed carrier rollers are captured between rails 24a and 24b 
and between rails 24c and 24d of opposed lower rail sets 24 for the 
support and longitudinal guidance of the lower folds or turnarounds of 
each conveyor serpentine loop. For enhanced control of the serpentine 
conveyor loops, opposed carrier rollers at the midpoints between the upper 
and lower folds are captured between rails 22a and 22b of the opposed 
intermediate rails sets 22. Disposed between rails 20c and 20d of the 
opposed upper rail sets 20 are coextensive screw feeder elements, one seen 
at 32 in FIG. 1, which are respectively rotatably mounted by the front and 
back magazine walls. Similarly, second, identical, longitudinally 
elongated screw feeder elements 34 are respectively rotatably mounted by 
the front and back magazine walls at locations between rails 24a and 24b 
of opposed lower rail sets 24. In addition, third screw feeder elements 
36, also rotatably mounted by the front and back magazine walls, are 
disposed coextensively between rails 22a and 22b of opposed intermediate 
rail sets 22. These screw feeder elements 32, 34 and 36 engage the 
opposed, rail-captured carrier rollers and are commonly driven in the 
manner described below to produce a controlled mass propagation or 
conveyance of the serpentine loops of formation 26a from left to right as 
indicated by arrow 37 in FIG. 3. 
Stationed at the right or exit end of magazine 12 (FIG. 3) is a first, 
unwrapping shuttle mechanism, generally indicated at 38, which is 
vertically reciprocated between the upper, intermediate, and lower opposed 
rail sets and operates to pick off the opposed carrier rollers 28a from 
these rails as they are conveyed to the exit or right ends thereof by the 
screw feeder elements 32, 34 and 36. An identical, second shuttle 
mechanism, generally indicated at 40 and stationed at the left of entry 
end of the magazine, is vertically reciprocated between the upper, 
intermediate, and lower opposed rail sets and operates to insert opposed 
carrier rollers between these rails at their left or entry ends. The 
unwrapping shuttle mechanism 38 and the wrapping mechanism 40 are driven 
in synchronous, in-phase relation, such that, as the former is picking 
carrier rollers from the rails to, in effect, progressively unwrap a 
serpentine loop at the right end of the serpentine formation, the latter 
is inserting carrier rollers onto the rails to, in effect, progressively 
form or wrap a serpentine loop at the left end of the serpentine 
formation. As each serpentine loop is formed, the screw feeder elements 
convey it to the right, making room on the rails for the next serpentine 
loop formation. 
As seen diagrammatically in FIG. 3, unwrapping shuttle mechanism 38 is 
equipped with cooperating sets of drive sprockets 42 and 44 for engaging 
therebetween the conveyor carrier rollers 28a and forcibly drawing them 
off the exit ends of the rails. Shuttle mechanism 38 also includes a set 
of idler accumulator sprockets 46 which are also reciprocated, but at half 
the velocity and half the stroke length of sprockets 42 and 44. Thus, 
while the vertical stroke of sprockets 42 and 44 extends substantially the 
full height of magazine 12, the vertical stroke of sprockets 46 extends 
only to approximately the level of intermediate rail sets 22. Their 
reciprocations are in phase such that sprockets 42, 44 and sprockets 46 
reach their respective upper and lower stroke limits simultaneously. From 
the unwrapping sprockets 42, 44, ammunition conveyor 28 is trained 
downwardly around accumulator sprockets 46, upwardly to and around a set 
of idler sprockets 48 journalled by the magazine front and back walls, 
across the top of the magazine past the idler sprocket sets 31 at 
stripper-feeder 30, and around a second set of magazine-mounted idler 
sprockets 50 to a set of accumulator sprockets 52 included with wrapping 
shuttle mechanism 40. This shuttle mechanism, being identical to 
unwrapping shuttle mechanism 38, thus further includes cooperating sets of 
drive sprockets 54 and 56 to which ammunition conveyor 26 is trained from 
accumulator sprockets 52 and between which the opposed carrier rollers 28a 
are engaged. As in the case of unwrapping drive sprockets 42, 44, wrapping 
drive sprockets 54, 56 are reciprocated through a vertical stroke 
extending the full height of the magazine to rack carrier rollers onto the 
opposed rail sets 20, 22 and 24, and thus wrap conveyor 26 into serpertine 
loops. The accumulator sprockets 52, like accumulator sprockets 46, are 
vertically reciprocated at half the velocity and half the stroke length of 
drive sprockets 54, 56, i.e., only from the level of the lower rail sets 
to approximately the level of the intermediate rail sets. Also, the 
reciprocations of sprockets 54, 56 and sprockets 52 are in-phase such that 
they simultaneously reach their respective upper and lower stroke limits. 
As noted previously, the reciprocations of the wrapping and unwrapping 
shuttle mechanisms are also driven in synchronous phase relation, such 
that all sprocket sets achieve their respective upper and lower stroke 
limits simultaneously. 
It will be appreciated that, in addition to successively unwrapping the 
serpentine loops from the rails, sprockets 42, 44 are driven at a rate 
necessary to accelerate the unwrapped serpentine conveyor loops from 
essentially zero velocity up to the requisite velocity to satisfy the 
prevailing gun firing rate. It will be seen that sprockets 42 and 44 are 
only required to accelerate the mass of the unwrapped serpentine loop, 
which represents a small fraction of the total mass of the conveyor and 
the live and spent ammunition rounds carried thereby. This represents a 
dramatic savings in ammunition feeding power requirements. Sprockets 54 
and 56 of wrapping shuttle mechanism 40, on the other hand, operate to 
decelerate the conveyor from gun-firing rate velocity to essentially zero 
as the carrier rollers are racked on the rails to form serpentine loops. 
The sets of accumulator sprockets 46 and 52 operate to take up conveyor 
slack during shuttle mechanism reciprocations. The bulk of the combined 
mass of conveyor 26 and its ammunition cargo is in serpentine formation 
26a and is thus supported by the rails sets. Moreover, this serpentine 
formation portion of the ammunition conveyor need be conveyed by the screw 
feeding elements 32, 34 and 36 at a very low velocity, e.g., five to ten 
percent of the gun firing rate velocity. These factors further reduce the 
ammunition conveyor power requirements. For example, a 30 millimeter gun 
system utilizing the present invention with a 1000 round magazine capacity 
would consume less than one horsepower at a 2400 shots per minute firing 
rate. This compares to a power consumption of nearly twenty horsepower for 
the same gun system equipped with a conventional ammunition feeding system 
wherein the entire ammunition conveyor is accelerated up to and driven at 
gun-firing rate velocity. 
Turning to FIG. 2, to drive unwrapping shuttle mechanism 38, a first, 
vertically oriented shaft 60 is mounted by journals 61 to the exterior of 
front magazine wall 14 adjacent its right vertical edge. This shaft mounts 
a series of three spur gears 62, 64 and 66 adjacent its upper end. Gear 62 
is engaged by a gear belt 68 to impart driving rotation to shaft 60. Gear 
64 drives a gear belt 70 trained around a spur gear 72 affixed to the 
upper end of a vertically oriented second shaft 74 which is mounted by 
journals 75 to the front magazine wall. The third gear 66 meshes with a 
spur gear 76 affixed to the upper end of a vertically oriented shaft 78 
which is mounted to the magazine front wall by journals 79. It is thus 
seen that all three shafts 60, 74 and 78 are rotated off the drive 
imparted by gear belt 68. 
Shaft 60 carries an elongated spline section 60a on which is slidingly 
received a worm 80 in meshing engagement with a worm gear 82 carried on 
the end of the shaft 42a mounting the set of shuttle sprockets 42. This 
shaft, whose ends are extended through vertically elongated slots 14a and 
16a in the front and back magazine walls 14 and 16, respectively, also 
carries a spur gear 84 which meshes with a spur gear 86 carried on the end 
of the shuttle sprockets 44 mounting shaft 44a also extending through wall 
slots 14a and 16a. These shafts 42a, 44a are journalled at their extending 
ends by tie blocks, the frontal one seen at 87 in FIG. 3, which serve to 
fix their vertically spaced relation and thus maintain the sets of shuttle 
sprockets 42, 44 in opposed carrier roller-engaging relation. An extension 
of front tie block 87 serves to mount worm 80. From this description, it 
is seen that shuttle sprockets 42 and 44 are driven off of shaft 60 in 
counter rotation to successively unwrap serpentine loops from the 
serpentine formation 26a and accelerate them to gun firing rate velocity. 
Still referring to FIG. 2, shuttle sprocket shaft 42a carries at each end 
follower gears 88 which mesh with internal, vertically elongated 
racetrack-shaped gears, one seen at 90. These racetrack gears are affixed 
to plates 92, which, in turn, are spaced from the front and back magazine 
walls by standoff posts 93 to which they are loosely pinned by bolts 94 
extending through longitudinally elongated plate slots 92a. By virtue of 
this mounting arrangement, the racetrack gears 90 are constrained against 
vertical movement, but are permitted a limited degree of longitudinal 
motion. The opposed racetrack gears are further formed with a recessed cam 
track 90a, of conforming racetrack shape, in which are received 
close-fitting, annular cam followers 88a carried at the very ends of 
shuttle sprocket shaft 42a. It will be appreciated that the cam followers 
are constrained to move only along the paths of their cam tracks, and thus 
serve to maintain follower gears 88 in continuous meshing engagement with 
their associated racetrack gears 90. Since these follower gears are being 
driven off of shaft 60, both rotation and vertical reciprocation of 
unwrapping shuttle sprockets 42 and 44 result. It will be noted that the 
racetrack gears are free to shift longitudinal positions as the follower 
gears negotiate the upper and lower turnaround gear sections thereof in 
effecting reversals in shuttle stroke direction. By virtue of this gearing 
arrangement the unwrapping shuttle sprockets are rotationally and 
reciprocatingly driven off the same drive shaft 60. 
As also seen in FIG. 2, shaft 78 carries three vertically separated worms, 
the upper and lower ones seen at 96, which drivingly mesh with worm gears 
98 carried on the ends of screw feeder elements 32, 34 and 36 operating in 
the front magazine wall-mounted upper, lower and intermediate rail sets 
20, 24 and 22, respectively. To provide drive for the back magazine 
wall-mounted screw feeder elements 32, 34 and 36, a vertical shaft (not 
shown) analogous to shaft 78, is mounted thereto and also carries worms 
for drivingly engaging the three screw feeder element worm gears, two of 
which can be seen at 98 in FIGS. 2 and 3. These two shafts each carry spur 
gears, the frontal one seen at 100, which are drivingly interconnected by 
a gear belt 102. It is thus seen that all six screw feeder elements are 
also commonly driven off of shaft 60 to convey the serpentine formation 
portion of the ammunition conveyor toward the unwrapping shuttle 
mechanism. 
It still remains to provide the reciprocating drive for accumulator 
sprockets 46 of the unwrapping shuttle mechanism. To this end, and as seen 
in FIG. 1 and 2, shaft 74 carries a level wind gear 104 which engages the 
frontal end of accumulator sprocket shaft 46a protruding through a 
vertically enlongated slot 14b in front magazine wall 14. This shaft 74 is 
duplicated beyond back magazine wall 16 to provide an identical level wind 
gear engaged by the rear end of accumulator sprocket shaft 46a protruding 
through a vertically elongated slot 16b in the back wall. Spur gears 106, 
affixed to the lower ends of these level wind gear shafts, are drivingly 
interconnected by a gear belt 108. As a result, the front and back level 
wind gears are driven in unison off of shaft 60 to reciprocate the 
accumulator sprockets 46 in coordination with the reciprocation of the 
unwrapping sprockets 42, 44 as described above. 
The geartrain described above for driving the unwrapping shuttle mechanism 
38 stationed at the exit or illustrated right end of magazine 12 is 
duplicated at the opposite or entry end of the magazine to drive wrapping 
shuttle mechanism 40 thereat. Shafts 60 of the frontal portion of the two 
geartrains are drivingly interconnected by gear belt 68, as seen in FIG. 
1. As illustrated, shaft 60 of the wrapping shuttle mechanism geartrain is 
extended at its upper end so as to carry a spur gear 110 which is engaged 
by a gear belt 112 driven by a suitable prime mover (not shown) for the 
ammunition feeding system 10. 
From the foregoing description, it is seen that the low inertia linear 
linkless ammunition feeding system of the present invention accommodates a 
dramatic reduction in the system prime mover power requirements. In 
addition to energy savings, reductions in prime mover size and weight are 
made possible, all of which are extremely important design considerations. 
It will be appreciated that the above-described shuttle mechanism 
drivetrains are merely illustrative and that modifications thereof in form 
or type will readily occur to those skilled in the art. While in the 
disclosed embodiment, the shuttle sprockets provide the sole means of 
driving the ammunition conveyor at the gun firing rate velocity, one or 
more of the illustrated sets of idler sprockets may also be driven to 
share this task. For certain applications, mid-level control and 
conveyance of the multiple serpentine loops may be unnecessary, permitting 
the omission of the intermediate rail sets 22 and the screw feeder 
elements 36 operating therein. While the screw feeder elements are 
illustrated as being driven at both ends, a single-ended drive may be 
found to work satisfactorily. It may also be found desirable to cushion 
the longitudinal position shifts of the racetrack gears 90 occurring when 
the shuttle sprockets reverse stroke directions. This would entail simply 
spring biasing the racetrack gears toward positions mid-way between their 
extreme longitudinal positions. In addition, rather than drivingly 
reciprocating the sets of accumulator sprockets 45, 52, it may be 
sufficient, particularly for small ammunition round sizes, to simply 
spring-bias them downwardly. While ammunition system 10 has been described 
with respect to the particular orientation shown in the drawings, it will 
be appreciated that it is operable in any spatial orientation. 
It is seen that the objects set forth above, including those made apparent 
from the foregoing description, are efficiently attained, and, since 
certain changes may be made in the disclosed construction without 
departing from the present invention, it is intended the the details 
embodied therein shall be taken as illustrative and not in a limiting 
sense.