Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates to the field of shell
feeders for automatic guns, and more particularly to shell
feeding apparatus for rapid fire, automatic cannon.
An extremely difficult role in modern warfare is
defending targets against low level, relatively close-in
attack by enemy aircraft. Because of difficulty in detecting
fast, low flying aircraft at sufficiently far distances to
enable effective use of surface-to-air missiles, this
critical defensive role is typically assigned to antiaircraft
weapons systems utilizing rapid fire, automatic cannon.
As a result of tradeoffs among such factors as range,
trajectory, firepower, mobility and cost, automatic cannon
in the calibre range of 30-40mm are commonly used in this
role. Maximum range of these type cannon is at least about
5000 meters; however, when used against low level aircraft
attacking at speeds up to about Mach 1 (approximately 340
meters per second at sea level) the most effective target
range has generally been found to be between about 1000
and 3000 meters.
2~ Because of their relatively high attack speed, low
level and maneuvering, attacking aircraft in the mentioned
optimum effective range can ordinarily be tracked for only
a few seconds during each attack pass. Therefore, to
enable a sufficlently high target.aircraft hit and kill
rate to protect vital targets and deter attack, the anti-
aircraft guns must be capable of such rapid firing rate
as to provide a defensive curtain of fire or shot gun
effect~
2 --
5~
In consequence, although usually fired only in
short bursts of 10-20 rounds because of generally limited
shell capacity, instantaneous firing rates of individual
antiaircraft cannon used for close-in defense must be at
least several hundred rounds per minute. Thus, as an
illustration, typical gas operated, automatic 35mm cannon
of the type commonly used in antiaircraft systems have
instantaneous firing rates of about 500-600 rounds per
minute. Ordinarily these cannons are used in pairs to
increase the firing rate to between 1000 and 1200 rounds
per minute.
Other types of substantially faster firing auto-
matic cannon, for example, multi-barrel, Gatling-gun types
and multi-chambered revolver types which may have more than
one barrel, have been developed and are available. However,
for a number of reasons, such types are principall~ designed
for airborne applications and are not widely used for ground
based antiaircraft roles, at least not in those requiring
high mobility and calibres greater than about 20mm.
A disadvantage of multi-barrel guns is that, because
of being relatively massive in large calibres as a result
of the several barrels used, the cannon require greater
amounts of power during operation to rotate the barrels
than is ordinarily availabe or feasible for mobile anti-
aircraft systems. An additional disadvantage is that asthe barrels are being rotated up to full speed, the first
` few shells fired are usually thrown off target in an un-
predictable manner. This causes initial portions of each
burst to be generally ineffective and wasteful of shells.
~0 Although not necessarily of severe disadvantages to small
calibre cannon having large capacity ammunition belts,
this characteristic is very disadvantageous for large
-- 3
.
5~
calibre cannon having only limited shell supplies and
firing only in short 10-20 round bursts. A still further
disadvantage of multi-barreled guns, as well as of multi-
chambered revolver-type guns, is that unfired shells left
in the barrels ~or chambers) at the end of a burst are
susceptible to being inadvertently fired by heat from the
barrel or chamber walls. Unless these shells are quickly
ejected, hence being wasted, potentially disastrous "cook
off" shell firing may occur.
Accordingly, assuming use of generally conventional,
gas operated cannon for close-in air defense weapons systems,
improvements increasing individual cannon firing rates are
necessary to offset continually improved performance of
attacking aircraft and their associated attack weaponry.
Even in applications in which existing cannon firing rates
are not unacceptable, improvements are needed to increase
reliability, since the cannons are operating at their
current limits of capability~
Because commonly used,gas operated antiaircraft
cannon operate on an axially reciprocating bolt principle,
in which shell loading and firing occur on a forward bolt
stroke and fired shell casing extraction and ejection
occur on a rearward bolt stroke, firing rates are dependent
on bolt cycling time. Accordingly, any increase in firing
rate requires a decrease in bolt cycling time, by increasing
bolt speed and/or by reducing length of the bolt stroke.
Bolt speed is, however, normally limited by mechanical
stresses caused by rapid acceleration and deceleration of
relatively massive moving bolt assemblies and from shell
pick up impact forces. As a typical example, bolt assemblies
of 35mm cannon may weigh about 20 pounds, the shells weighing
about 3.5 pounds. To prevent stress damage or excessive wear
of parts, maximum allowable 35mm bolt speed is currently
between about 50-60 feet per second~
.
- 4 ~
- - ,
Length of the bolt stroke is, on the other hand,
determined to a great extent bv the distance needecl for
picking up a shell and moving the shell inwardlY towards
the bore axis and forwardly into the breech. Given a
specific bolt forward speed, bolt stroke length is also
dependent upon the time required for feeding a shell into
the bolt pick up position between shots.
As is readily apparent, as bolt speed is increased
and bolt stroke is decreased to increase firing rate,
allowable shell feed time is decreased, as is lengt~ of
the shell path after pick up. Consequentlv, limitations
on reliable feeding of shells ordinarily dictate firing
rate of automatic cannon, shell feeding improvements being
necessary to further increase firing rate of such weapons.
As illustrations of problems encountered at high bolt
velocities and short bolt strokes, shells may sometimes
not be fed fast enough to be in position for picking up
by the bolt. As a result, the bolt closes on an empty
chamber and firing is interrupted while the cannon is
recharged. If the shell feed path after pick up is
marginally short, shells may become jammed as they are
driven forwardly, causing gun jamming and possibly also
dangerous impact-caused firings.
Belt feeding of shells, as is commonly used for
machine guns and small calibre cannons, generally cannot
be used, at least alone, for feeding shells to large
calibre, rapid firing automatic cannon. This is principally
because of the difficulty in rapidly advancing, without
damage, even relatively short portions of a fully loaded
belt of large calibre shells, due to combined weight of
the shells. Even if sufficient belt drive power can be
provided, usually from a source external to the cannon,
without causing slowing of the cannon firing rate, the
- 5
required grea~ belt advancing forces tend to pull belt
links apart or to damage shells to an extent making both
shell feeding of the cannon and fired shell casing extraction
and ejecting difficult and unreliable.
As an alternative to belt feeding, shell magazines
are used by most gas operated antiaircraft cannon. As a
typical example, in the shell feed apparatus used with
Oerlikon 35mm antiaircraft cannon, shells are clip fed
into a magazine attached to the cannon. Within the magazine,
the shells are stripped from the clips and are then fed into
a segmented, endless conveyor which then advances the shells
to a cannon shell pick up positionO A typical Oerlikon 35mm
cannon magazine holds seven, seven round clips, the con-
veyor advancing a series of eight shells. External power,
including an electrically wound, mechanical spring motor,
operates the Oerlikon magazine.
However, even with external power, the conveyor when
advancing eight shells, weighing a total of about 28 pounds,
cannot be driven fast enough, without damage to the shells
or conveyor, to enable firing rates much greater than about
550 rounds per minute. Furthermore, since the magazine
spring motor is capable of feeding only about 10 shells
before unwinding, the spring must be continually rewound
by the associated electric motor. If the auxiliary electric
power is lost, for example, due to battle damage, the spring
motor must be manually wound at least every ten rounds.
~7hen this is necessary, ability to rapidly fire series of bursts,
- as is often necessary in combat situations, is greatly im
paired and effectiveness of the entire weapons system is
; 30 consequently dangerously reduced.
. .
Because of these and other problems with heretofore
available (or disclosed) shell feeding apparatus or auto-
matic cannon, applicant has invented an improved, two stage
shell feeding apparatus which enables rapid, reliable shell
feeding without shell or feeding damage and at high firing
rates, without necessity for an external source of power.
In addition, applicant's apparatus provides controlled shell
feeding from the shell pick up position to the cannon breech,
thereby enabling reducing of bolt stroke length with subse~uent
reduction of bolt cycling time and increase in firing rate or
enabling improved feeding at current firing rates.
Accordingly, for a gun having a bolt operakive for
axially reciprocating past a loaded shell pick up position
which is offset from the barrel bore axis of the gun, to
sequentially pick up shells therefrom on forward bolt travel
for loading into a gun firing chamber, applicant's two stage
shell feeding apparatus comprises a first stage shell feeding
rotor having surface regions defining a plurality of peripheral
shell holding cavities spaced apart around the rotor, and shell
supply means for supplyinq shells, as free shells, to the
rotor. Means are provided for rotatably mounting the rotor
for enabling transfer thereby of shells from the supply means
into the shell pick up position. The rotor mounting means
are configured for positioning the rotor relative to the
shell supply means and the shell pick up position for causing,
when any one of the rotor cavities is indexed into the shell
pick up position, another one of the rotor cavities to be
positioned in shell receiving relationship with the supply
means.
-- 7 --
Included in the apparatus are relatively fast
first stage actuating means operated by pressurized gases
from firing of the gun, for causing, after the gun is
fired, and prior to the recoiling bolt moving rearward~y
of the shell pick up position, partial rotatlon of the rotor
to index a rotor cavity holding a shell into the shell pick
. up position to enable picking up of the shell by the bolt
on subsequent forward bolt travel and simultaneously to
index an empty cavity, preferably a cavity adjacent to the
cavity in the pick up position, into shell receiving relation-
ship with the supply means.
: Relatively slow second stage shell feeding means,
operated by pressurized gases from the same firing of the
gun, are provided for causing, after the first stage actu-
ation means has rotatably indexed the rotor and before a
next firing of the gun, the advancement of a plurality of
shells in the supply means toward the rotor and the transfer
of a free shell from the shell supply means into the empty
rotor cavity indexed therewith with the rotor being complete-
ly isolated from the shell supply during shell feeding
~ rotor rotation, resistance to said shell feeding rotor
: rotation being thereby minimized.
This structure permits the fast rotor action to
occupy only a minor part of the firing cycle (the time
between successive firing of shells during automatic firing),
: so as to leave the major part of the firing cycle for the
advancement of a plurality of shells in the shell supply
: and the feeding of a free shell into an empty rotor cavity
.. indexed with the supply. This results in a faster and
smoother operating over-all feeding apparatus, especially
~- for cannon-size shells, and enables the cannon to fire at
a higher rate of fire.
:` 'A`
,~ .
~ _
~ ~ ~3~ ~t~
In the illustrated embodiment of the invention,
the relatively fast rotor actuating means is operatively
coupled to the relatively slow shell feeding means to produce,
upon each sequential firlng of a shell, se~uential operation,
first of the actuating means within approximately the first
25% of the firing cycle, and thereafter the shell advancement
and transfer of the shell feeding means during the remainder
of the firing cycle.
Further, because a free shell is supplied to the
rotor, as opposed to running belted or linked shells through
the rotor, the rotor operation is isolated from the shell
supply, and is not required to pull on a series of linked
rounds. Since the shells in the rotor are free (as opposed
to linked), a shell retaining means may be mounted intermed-
iate the rotor and the cannon adjacent the shell pick up
position for retaining in the rotor a free shell disposed
in whichever rotor cavit~ is indexed into the shell pickup
position.
The illustrated embodiment of the invention includes
various implementing features.
More specifically, the rotor mounting means include
a rotor shaft mounted for bidirectional rotoation, the rotor
being rotatably mounted on the rotor shaft. Means are in-
cluded for limiting rotor rotation to a single shell index-
ing direction while ratchet means are provided for inter-
connecting the rotor to the rotor shaft for enabling shell
indexing rotation of the rotor by the rotor shaft and sub-
se~uent return rotation of the shaft without rotor back up
movement.
g
The first stage actuation means is conencted to a
first end of the rotor shaft and second stage actuation
means, configured ~or actuating the second stage feeding
means, are connected to a seconcl end of the rotor shaft.
To prevent overtravel of the rotor and movement of
the shell indexed into the shell pick up position out of
such position, anti-surge means are provided for locking
the rotor against rotational movement during shell trans-
ferring of a shell from the supply means into the emptv
rotor cavity by the second stage feeding means. The ratchet
means are configured for causing disengagement or unlocking
of the rotor from the anti-surge means during initial shaft
rotation in response to a next firing of the gun and before
subsequent rotational indexing of the rotor by the first
stage feeding means.
Comprising the rotor shaft are a tubular main shaft,
to opposite ends of which first and second actuation means
crankarms are fixed, having disposed axiall~ therethrough
an elongate torsion bar. The torsion bar, fixed against
rotation at a first end and nonrotatablv connected to the
main shaft at a second end, provides rapid return rotation
of the main shaft without requiring any return driving forces
from the second stage feeding means which might slow oper-
ation thereof. The rapid return rotation of the main shaft
enables rotor locking by the anti-surge means before second
stage shell transferring into the rotor is completed to
` prevent rotor overdriving.
Shell retaining means are mounted intermediate the
rotor and the gun adjacent to the shell pick up position for
retaining in the rotor a shell contained in whichever rotor
cavitY is indexed into the shell pick up position. Config-
uration of the shell retaining means permits forward extrac-
tion of the shell from the indexed cavity by the bolt on
forward travel thereof past the shell pick up position.
-- 10 --
~,
The shell retaining means include flrst and second feed lip
members laterally spaced apart a distance enabling shell
pick up engagement therebetween, by the bolt, of a shell
contained in the rotor cavity indexed into the shell pick
up position.
The lateral spacing distance increases toward the
front of the pick up position so that the shell feeding lips
are diverging in that direction and are spaced and contoured
to continuously engage and guide the forwardly stripped shell
toward the cannon firing chamber along a substantial portion
of the shell path.
Means are also provided for enabling the bolt to be
seared up at the end of a burst in a fully charged condition
in readiness for a next firing, when conventional searing up
would otherwise require recharging of the gun before a sub-
sequent firing. Such means include sensing means for sensing
when no shell is in the rotor cavity indexed into the shell
pick up position and no shell is in a next-to-the-last shell
position, relative to shell transferring to the rotor, in
the shell supply means. An electrical signal adapted for
initiating bolt searing up the next time the bolt is in a
searing up position rearwardlY of the pick up position, is
provided in response to sensing that the shell pick up
; position and the next-to-the-last shell position are sim-
ultaneously empty of shells.
When the rotor is configured so that whenever one
cavity is indexed into the shell pick up position, an
adjacent cavity is in shell transferring relationship
with the shell supply means, firing is thus stopped with
shells contained in both the cavity indexed into the shell
pick up position and the next adjacent cavity indexed in
shell receiving relationship with the shell supply means.
The first stage actuation means includes a gas
cylinder having a piston, a crankarm fixed to one en~
of the rotor mounting shaft and means pivotally interconnect-
ing the piston to the crankarm. Included are means for
supplying pressurized barrel gases to the cylinder to
cause movement of the piston, and hence rotation of the
rotor shaft and rotor indexing in response to firing of the
gun. Thus no external shell feeding drive means, such as
electric or mechanical motors are required nor does oper-
ation of the apparatus slow operation of the gun. Included
in the second stage actuation means is an actuation element
connected to the second stage crankarm operative for causing
compressing of springs in slide portions of the second
stage feeding means in response to turning of such crankarm
by the rotor shaft. Upon return of the actuation element,
the slide springs connected to an advancing member of the
slide portion cause advancing of shells in the supplv means
towards the rotor and transferring of an end shell into the
adjacent rotor cavity.
To provide access to inner reglons of the feeding
apparatus, particularly the first stage feeding means, the
rotor mounting means mounts the rotor to the gun in a
manner enabling pivoting of the rotor away from the gun.
When the shell pick up position is laterally offset
from the barrel bore axis of the gun, feed path control
means are provided for controlling inward and forward move-
ment of shells as the shells are fed from the pick up pos-
ition into the firing chamber. Such feed path control
means include configuring rotor surface regions defining
the shell holding cavities and the shell retaining means
to have shell engaging surface regions cooperatively con-
figured for providing controlledand guided forward and
inward shell feeding movement as a shell, picked up from
the cavity indexed into the shell pick up position, is
~` :i
- 12 -
ariven by the bolt toward and into the gun firing chamber.
This feed path controlling is, particularly at high firing
rates assures reliable feeding of shells, without damage
thereto or jamming of the gun, into the firing chamber.
Such feed path control is adapted for application to many
types of guns. Accordingly~ for a gun having shell supply
means for containing shells to be fed into the gun and a
bolt operative for axially reciprocating past a shell pick
up position which is offset relative to a barrel bore axis
of the gun and for picking up shells therefrom on forward
bolt travel for loading into a gun firing chamber along a
preestablished shell feed path, shell feeding apparatus
comprises shell transferring means for transporting shells
from the shell supply means to the shell pick up position,
the transferring means including means defining at least one
cavity configured for holding a shell transferred into the
shell pick up position until the shell is picked up therefrom
the bolt. The cavity defining means is configured to
approximately match the external configuration of a free
shell around a substantial portion of the shell perimeter,
but is gradually longitudinally bowed inwardly toward the
axis of the rotor along its rearward portion to facilitate
a short steep shell feeding path while providing a guiding
surface for smooth movement of the shell from the rotor
cavity to the cannon firing chamber for at least substantial
portions of the shell feed path. ~ncluded is a pair of shell
feed lip members disposed adjacent the shell pick up position,,
the feed lip members being configured for preventing radial
movement of a shell from the pick up position towards the
barrel bore axis and being further configured for maintaining
guiding engagement by portions thereof with a shell being
picked up from the pick up position for at least substantial
portions of the shell feed path.
- 13 -
The shell cavity defining means is configured to
enable a rearward end of a shell picked up by the bolt from
the pick up position to move away from the barrel bore axis
to enable a steeper shell feed path.
Shell deflector means may be disposed forwardly of
the pick up position for causing additional shell deflection
towards the barrel bore axis, as may be desired for some gun
configurations and/or firing rates.
As a result of configuration of the two stage shell
feeding apparatus, a single shell (assuming a four cavity
rotor) is rapidly rotated into the shell pick up position
during an initial portion, for example, about 25 percent,
of the cycling time after firing so as to assure presence
of a shell for picking up by the bolt on counterrecoil. The
remainder of the cycling time is allowed for the slower
advancing of shells to load the rotor. The feed path control
continues controlled loading of the shells into the gun
firing chamber.
To prevent shell impact damage, which could cause
impact firing or affect subsequent casing extraction and
ejection after firing, shell accelerating means may be pro-
vided for causing, in response to forward bolt impact, for-
ward acceleration of a shell in the pick up position prior
to engagement between the bolt and the shell. The shell
accelerating means accelerates the shell in the pick up
position to approximately bolt forward velocity before the
bolt engages the shell base for continued forward driving
of the shell into the firing chamber.
~,
- 14 -
Comprising the shell accelerating means are a shell
accelerating element and means for pivotally mounting the
element rearwardly of a shell positioned in the pick up
position and along the path of bolt travel. The element
is formed having a forward, convex shell base engaging surface
and a bolt engagement portion. Forward impact b~ the bolt
against such bolt engagement portion causes the element to
pivot forwardly so that the shell base engaging surface drives
or pushes the shell forwardly ahead of the bolt. The pivotal
mounting means also enable the element to pivot rearwardly in
response to rearward bolt impact against the element, thereby
permitting the bolt to travel rearwardly under the element,
for example, during recoil after firing. r~eans are provided
for causing the shell accelerating element to return to a
central position in readiness for shell acceleration, after
the element has been provided either forwardly or rearwardly
by the bolt.
Preferably, the shell base engaginq surface of the
shell accelerating element is contoured to enable contact to
be maintained between the surface and the shell base without
bouncing as the accelerator element is pivoted forwardly by -
the bolt to cause shell acceleration. This reduces stresses
and parts wear and assures uniform shell acceleration.
Although particularly useful in the two stage shell
feeding apparatus because such apparatus is particularly
adapted for high firing rates having associated therewith
high bolt velocities, which could cause hi~h shell impact
stresses, the shell accelerating means is adaptable to other
types of shell feeding apparatus. That is, configuration
and operatior of the shell accelerating apparatus is relativelv
independent upon configuration of the shell feeding apparatus.
~,, ,
A better understanding of the present invention may
be had from a consideration of the following detailed des-
cription, taken in conjunction with the accompanying drawinys,
in which:
Figure 1 is a partiallv cut away, perspective drawing
of a two stage shell feeding apparatus for an automatic gun,
according to the present invention, showing ~irst stage shell
feeding means for rotatably transferring shells to a shell
pick up or ram position of the gun and showing second stage
shell feeding means for advancing shells from a shell supply
means into the first stage shell feeding means;
Figure 2 is a partially cut away, perspecti~e drawing
showing the first stage feeding means and associated first and
second actuating means mounted to a gun cradle which is in
turn attached to a gun turret containing the shell supply
means, the gun cradle being shown in an open configuration
permitting access to the feeding apparatus;
Figure 3 is a perspective drawing, looking forwardly
from an under side of the cradle mounted portion of the shell
2Q feeding apparatus, showing shell rotor and feed lip portions
of the first stage feeding means and showing second actuating
means associated with the second stage feeding means;
Figure 4 is a perspective drawing, similar to Figure 3
but looking rearwardly from an under side of the cradle mounted
shell feeding portion, showing gas operated first actuating
means associated with the first stage feeding means;
Figure 5 is a partially cut away, exploded drawing of
rotor portions associated with the first stage feeding means,
showing configuration of rotor shell transferring cavities and
ratcheting and anti-surge means for controlling rotor rotation;
- 16 -
Figure 6 is longitudinal cross sectional view, taken
along line 6-6 of Figure 2, showing features of the shell
rotor and mounting means therefor, and shell accelerator
means mounted for engaging a base region of the shell;
Figure 7 is a partial longitudinal cross sectional
view, taken in the plane of Figure 6, showingl in enlarged
form, features of the rotor ratcheting and anti-surge means,
with the rotor locked against rotation;
Figure 8 is a transverse cross sectional view of the
cradle mounted portion of the shell feeding apparatus, taken
along line 8-8 of Figure 4, showing rotor and feed lip con-
figuration in a rearward region and showing associated portions
of the shell supply means in phantom lines;
Figure 9 is a transverse cross sectional view of the
cradle mounted portion of the shell feeding apparatus, taken
along line 9-9 of Figure 4, showing rotor and feed lip con-
figuration in a forward region;
Figure la is a cross sectional view, taken along line
l~lQ of Figure 4, showing features of the gas ~perated, first
2a actuating means associated with the first stage feeding means;
Figure 11 is a partially cut away, transverse sectional
view of the shell feeding apparatus, taken along line 11-11 of
Figure 2, showing the cradle of Figure 2 closed against the
turret side and showing the first and second stage shell feeding
means in operative relationship with the shell supply means
and t~e ~un;
Figure 12 is a transverse sectional view, taken along
line 12-12 of Figure 1, showing features of the shell advancing
slide and shell supply vane;.
Figure 13 is a cross sectional d~awing taken generally
in the plane of Figure 6, showing layout of a shell feed path
from the shell pick up position into the gun breech;
- 17 -
Figure 14 is a series of transverse cross sectional
views showing shell guiding along the shell feed path,
Figures 14(a) - 14~fJ being taken along lines 14(a) - 14(a)
through 14(f) - 14(f) of Figure 13;
Figure 15 is a series of two cross sectional views
similar to Figure 7, showing operation of the rotor ratchet
and anti-surge means; Figure 15(a) showing unlocking of the
rotor from an anti-surge ratchet during early rotor shaft
rotation; and, Figure 15(b) showing unlocking of the rotor
from a rotor ratchet during rotor shaft return rotation;
Figure 16 is a time sequence series of pictorial
diagrams depicting two stage shell feeding during gun
charging and firing; Figure 16(a) showing the rotor, at a
prefiring time, in shell receiving relationship with a
shell magazine segment, the empty rotor having been rotated
90 during a first part of a first charging operation; Figure
16(b~ showing second stage feeding of shell No. 1 into an
empty rotor cavity during the last part of the first charging
operation; Figure 16(c) showing additional 90 rotor rotation
during the irst part of a second charging operation, thereby
rotating shell No. 1 into the pick up position; Figure 16(d)
showing trans~er of shell No. 2 into an empty rotor cavity
during the last part of the second charging operation, the
~ gun being seared up ready for firing; Figure 16(e) showing,
after initiation of firing, shell No. 1 stripped from the
rotor by the unseared bolt; Figure 16(f) showing the rotor
rotated 90 in response to firing of shell No. 1, thereby
rotating shell No. 2 into the pick up position as the bolt
starts recoiling and, Figure 16(g) showing the subsequent
second stage advancing of shell No. 3 into the rotor;
- 18 -
; Figure 17 is a time sequence series of pictorial
diagrams depicting an end-of-firing sequence; Figure 17(a)
showing shell No. 8 (of 10 shells) rotated by the rotor into
the pick up position in response to firing shell No. 7;
Figure 17(b) showing shell No~ 9 being subsequently transferred
to an empty rotor cavity, with simultaneous advancing of shell
No. 10 to the last slide position, with shell No. 8 having
already been picked up by the bolt, a searing up signal being
provided by the next-to-the-last slide position and the pick up
position being simultaneously empty; Figure 17(c) showing
rotation of shell No. 9 into the pick up position, in response
to firing of Shell No. 8; Figure 17~dl showing subsequent
transfer of shell No. 10 into an empty rotor cavity, the bolt
being researed; and, Figure 17(~e) showing a next magazine
segment, holding shells 1' - 10', indexed into shell transfer-
ring relationship with the rotor which still contains shells
No. 9 and No. 10 from the first magazine segment; and
Figure 18 is a pictorial diagram showing an example
of relative displacements, versus time after firing, of the
2Q cannon bolt, the rotor and the shell advancing slide during
gun firing; Figure 18(a) showing ~olt displacement relative
to the gun breech; Figure 18(b) showing rotor angular dis-
placement; and, Figure 18(c) showing slide displacement.
In Figures l.and 2 a two stage shell feeding apparatus
20, according to the present invention, is illustratedmounted for feeding shells 22 from a shell supply means 2~
into an exemplary automatic cannon or gun 26 of a type adapted
for use in an antiaircarft weapons system 28, (Figure 2) only
portions of the latter being shown. For illustrative purposes,
the cannon 26 is depicted in Figure 2 as an open receiver,
gas operated type, an associated axially reciprocating bolt or
bolt assembly 30 being shown in a seared up position rearwardly
of the feeding apparatus 20.
By way of example, the cannon 26 is shown received into
a gun cradle 32 pivo~ally mounted, for opening and closing, to
a side pla~e 34 which is, in turn, rotatably connected, for
gun elevational movement, to a weapons system turret or cupola
36~ The cradle 32 is shown in a fully open, non-firing,
pOSition on the turret 36, as is used for access to the shell
- feeding apparatus 20 and other portions of the cannon 26.
As shown for illustrative purposes, the shell supply
means 24 comprises a rotating drum magazine 38 mounted inside
the turret 36, the shells 22 being fed from the magazine 38
to the cannon 26 through an aperture 40 in the side plate 34.
The exemplary magazine 38 is divided into a relatively large
number of pie-shaped drum segments 42, each holding, for example,
lQ, clip-mounted shells 22. ~owever, as will be apparent from
the ensuing description, the shell feeding apparatus 20 is
adaptable for use with virtually any type of shell supply
means, including hopper and belt types
Furthermore, although the shell feeding apparatus 20
is shown configured such that a major portion 44 thereof is
2a mounted directly onto the cradle 32, directly above the cannon
26 as is preferred for the particular type cannon 26 and
weapons system 28 shown, it is to be appreciated that the shell
feeding apparatus is readily adaptable for use with most types
of automatic cannon ~or guns) which operate on an axially :
reciprocating bolt principle. Thus, for the exemplary cannon
26, the bolt 30 is operative for stripping one of the shells
22 indexed.into a shell pick up or ram position 48 (shown in
Figure 13 in phantom lines) in the shell feeding portion 44
on a forward or counterrecoil stroke either rom an initial
rearward seared up position or in counter-recoil from a rear,
recoil buffer 50 and towards a cannon breech or firing chamber 52
(shown in Figure 1 in phantom lines). Thus, the bolt 30 passes
the loaded pick up position 48 both during recoil from the breech
; - 20 -
~a~
52 on firing and an counterr0coil from the buffer S0 there-
after, the longitudinal axis 5~ of the pick up position being
offset from (above in Figures 1 and 2) the bore axis 56 of
an associated cannon barrel 58.
As seen in Figure 1, the shell feeding apparatus 20
which, in response to firing of the cannon 26, feeds the
shells 22 from the shell supply means 24 into the cannon
in two steps, comprises generally rapid acting, rotary first
stage feading means 60 and typically slower acting, linear
second stage feeding means 62. Interconnected first and second
stage actuating means 64 and 66, respectively, are provided
for operating the first and second stage feeding means 60 and
62, as described below. Although other types of driving may
alternatively be employed to a~vantage, the first and second
actuating means 64 and 66 are shown configured for operation
by high pressure barrel gases, which are fed to the first
a ctuating means from the cannon barrel 58 (~;gure 2) by gas supply
means 70.
Included in the first stage feeding means 60 is a shell
rotor 76 formed having a plurality of longitudinal, external
, shell holding cavities 78 which are equally spaced around the
rotor periphery. For the rotor 76 shown, four cavities 78,
spaced at 90 intervals, are used. The second stage feeding
means 62 includes a linear shell advancing slide 80, made
sufficiently long to span all the shells 22, for example, ten,
contained in any of the drum segments 42, one such slide
being provided for each of the segments and rotati~g therewith.
Assuming precharging of the rotor 76, upon ~iring of
the cannon 26, the first actuating means 6~ immediately
rotates the rotor 76, in the direction of Arrow "A" (~igure
1), a partial turn (90 for the four cavity rotor shown) to
index a shell containing cavity 78 into the shell pick up
position 48. This rotor turning and shell indexing is prefer-
ably timed to occur, as described below, sufficiently in
- - 21 -
advance of the bolt 30 impacting the buffer 50 and rebounding
forwardly in counterrecoil to assure stable positioning of a
shell in the pick up position before pick up.
After such rotor indexing, and sometime during the
rest of the bolt cycle time, the slide 80, actuated by the
second actuating means 66, moves all the shells 22 remainin~
in the associated segment 42 one shell position (direction of
Arrow "B") to advance an end one of the shells into an
adjacent empty one of the rotor cavities 78.
When the segment 42 is fully loaded or contains a
number of shells 22, the second stage feeding operation
necessarily is slower than the first stage rotation ~f only
a single shell through 90. Thus, the rapid first stage
feeding assures a shell is stabilized in the shell pick up
position before the time of pick up and enables a relatively
slower~second stage shell transfer to the rotor 76. As an
example, and as more fully discussed below, the first stage
feeding typically occurs within the first 20-25 percent of
the firing cycle time, leaving the remaining 75-80 percent
of cycling time for the slower second stage feeding.
This two stage feeding is important because of the
difficulty of advancing an entire segment of shells 22 in a
single step fast enough to assure a shell is in position for
picking up on bolt counter-recoil. Thus, at least for
fully or nearly fully loaded segments 42, single step feeding
tends to be unreliable at even moderate firing rates.
More specifically, as seen in Figures 3 and 4, the
shell feeding portion 44, which is mounted on the cradle 32,
includes the first stage feeding means 60, the first and
second actuating means 64 and 66, rotor mounting means 82,
rotor rache~ing and anti-surge means 84, first and second
feed lip members 86 and 88, respectively, shell deflector
means 90 and shell accelerator means 92.
- 22 -
.
Comprising the rotor mounting means 82 are rigid,
spaced apart, front and rear end plates 98 and 100, respect-
ively, which are generally triangular in shape. Includedalso are a rigid rectangular side plate 102, which intercon-
nects the front and rear end plates 98 and 100, and a shaftassembly 104 mounting the rotor 76 and the associated ratchet
and anti-surge means 84 between such plates. Included also
are first and second, laterally spaced apart pivot rods 106
and 108, respectively, which extend between the front and
rear plates 98 and 100, at opposite lower corner regions
thereof, the rods functioning to pivotally and releasably
attach the rotor mounting means 82 to the gun cradle 32.
In addition, as further described below, portions of the
first rod 108 also function as part of the gas supply means
70.
Rigid longitudinal separation of the front and rear
plates 98 and 100, through which opposite end regions of the
rotor shaft assembly 104 are rotatably mounted, is by the
side plate 102, the feed lip members 86 and 88 and the rods
106 and 108.
As also seen in Figures 6 and 7, attached to a forward
surface 110 of the front plate 98, relatively adjacent to the
rotor shaft assembly 104, are the first actuating means 64,
a crankarm 112 of which is fixed to a forward end of such
shaft assembly. Also mounted to the forward surface 110, in
a position to engage the shell 22 as it is stripped forwardly
from the shell pick up position 48, are the shell deflector
means 90.
In a similar manner, the second actuating means 66 are
attached to a rearward surface 114 of the rear plate 100 rel-
atively adjacent to the rotor shaft assembly 104, a crankarm116 of the second actuating means being fixed to a rear end
of the shaft assembly. Also attached to the rear plate sur-
face 114, so as to be rearwardly adjacent to whichever shell
- ~3 -
22 is in the shell pick up position 48, is the shell
accelerator means 92.
Mounted to a forward surface 118 (Figure 8) of the
rear plate 100 are first and second, spring loaded shell
positioning and retaining detent means 120 and 122, respect-
ively. Mounted to an inner surface 128 of the side plate
102, for engagement with peripheral regions of the rotor 76
are ratchet-type spring loaded, rotor anti-backup means 130
(~igure 7~ which pr~vent reverse direction rotor rotation, as
described below.
Also as described below, the feed lip members 86 and
88, together with the shell deflector means 90 and whichever
one of the rotor cavities 78 is indexed into the pick up pos-
ition 48, cooperatively provide feed path control for shells
stripped from the rotor 76 by the bolt 30.
Because the feed lip members 86 and 88 are positioned
between the rotor 76 and the bolt path, opposing edge regions
of the members, adjacent to the pick up position 48, are later-
a lly separated a distance sufficient to enable shell stripping
engagement between the bolt 30 and whichever shell 22 is
indexed into the shell pick up position. Closest opposing
edge regions of the feed lip members 86 and 88 are thus
separated by~a gap 132 which is everywhere at least sufficiently
wide to permit longitudinal passage of a shell rammer 134
which is mounted to forward upper regions of the bolt 30.
However, in a rearward region 136, edges of the gap
132 are stepped apart to a width greater than that of narrow-
est gap regions immediately forward thereof to provide clear-
ance for an accelerator member 138 of the shell acaelerator
means 92. In a mid region 140 of the gap 132, edges of the
gap diverge in a forward direction to enable guided movement
of shells stripped from the pick up position 48 inwardly and
forwardly towards the firing chamber 52; while in a forward-
- most gap region 142, edges of the gap are stepped farther
- 24 -
~'
apart to enable shell passage therethrough.
The first feed lip member 86 is also configured for
confining, in the rotor 76, the shells 22 being transferred
by the rotor from the shell supply means 24 to the shell pick
up position 48 during rotor rotation. Accordingly, an
arcuate, rotor facing surface 148 ~Figure 8~ of the first
feed lip member 86 is formed having substantially the same
radius as outer surfaces of the rotor 76, the rotor facing
surface being spaced closely adjacent to the rotor in the 90
quadrant of rotor shell transfer.
To index the rotor held shells 22 in 90~ rotational
steps, between the shell supply means 24 and the shell pick
up position 48, incremental, unidirectional rotor rotation
(in the direction of Arrow "A". Figures 1, 8 and 9) is
required. However, due to piston operation, through the
shaft mounted crankarm 112, of the xotor shaft assembly 104
on which the rotor 76 is mounted, shaft rotation first in the
direction of rotor advancement and then return rotation to
the initial shaft position is necessary. This interrupted,
unidirectional 90 step indexing of the rotor 76 and recipro-
cating rotational movement of the shaft assembly 104 is
enabled by the rotor ratchet and anti-surge means 84, portions
of which couple the rotor to the shaft assembly, and by the
rotor anti-backup means 130 which prevents rotor counterrotation.
Return rotation, that is, counterrotation, of the shaft
assembly 104 is caused by torsional spring properties thereof.
This torsional spring action is enabled by constructing
the shaft assembly 104 to have an elongated torsion bar 154
disposed within a rigid tubular main shaft 156 (Figures 6 and
7). Only at rearward ends, corresponding to shaft connection
to the crankarm 116, are~the torsion bar 154 and the main
shaft 156 connected together. This connection may, as shown,
be by disposing a square cross sectional region 158 of the
torsion bar 154 within a corresponding squars cross section
- 25 -
.
aperture 160 at the rearward end of the main shaft 156.
At a forward end, however, the torsion bar 154 is
non-rotatably fixed relative to the front plate 98. A square
in cross section, torsion bar forward end region 162 is thus
non-rotatably received into a mounting bracket 164 which is,
in turn, fastened by several bolts 166 to the front plate.
Preferably, the bracket 164 is configured, and the bolts 166
are spaced, to enable incremental, rotational positioning of
the bracket relative to the plate 98, to thereby enable pre-
loading of the torsion bar 154.
Although rearward ends of the torsion bar 154 and the
main shaft 156 are fixed together, limited relative rotation-
al movement between the bar and main shaft is permitted in
other regions. Since the crankarm 112 is fixed only to the
main shaft 156, for example, by mating of square cross section
crankarm and shaft regions, rotational movement of the crank-
arm 112 by the first actuating means 64, and hence rotational
movement of the main shaft, causes twisting of the torsion
bar 154. Such torsion bar twisting provides the spring force
necessary for returning the main shaft 156, and hence the
crankarm 112, to their initial, unrotated positions. Because
of torsional rigidity of the main shaft 156, any rotational
movement of the crankarm 112 of the first actuating means 66
causes simultaneous, equal rotation of the crankarm 116
which is associated with the second actuating means 68.
Rotational mountiny of the main shaft 156, and
hence the rotor 76, is provided by a generally cylindrical
portion 172 of the crankarm 116, which is received into a
circular aperture 174 in the rear plate 1~0, and by a generally
cylindrical portion 176 of the crankarm 112, which is received
in a circular aperture 178 in the front plate 98 (Figures 6
and 7)O Confinement of the shaft assembly 104 against forward
~` axial movement is by a rearward surface 180 of the mounting
:`
- 26 -
~ ~ ~;r~ ~
bracket 164 bearing against a torsion bar annular shoulder
182 and by a shoulder 184 formed on the crankarm 116 which
bears against the rearward surface 114 of the rear plate 100
(Figure 6). Axially rearward ~ovement of the shaft assembly
104 is prevented by a rear rotor face 186 which bears against
! the forward surface 118 of the rear plate 100~ The rotor is
otherwise confined on the shaft assembly 104 by an annular
shoulder 188 formed around the periphery of the main shaft
156, which bears against a corresponding forward rotor face
region 190 (Figure 7).
Configuration of the ratcheting and anti-surge means
84 enables the rotor 76, after rotational indexing through
90, to remain indexed as the rotor shaft 104 is rerotated
to its initial position, and enables releasable locking of
the rotor against rotation which might otherwise occur when
shells are advanced by the second stage feeding portion 62
from the supply means 24 into the rotor. Comprising the
ratcheting and anti-surge means 84 are a rotor hub 192 which
forms a part of the rotor 76 and which is connected to a main
rotor portion 194 by a plurality of bolts 196; a rotor
ratchet 198; and anti-surge ratchet 200; a bearing member
202 and a compression-type ratchet spring 204.
As seen in Figures 5-7, the bearing member 202, which
: is generally tubular in configuration, is mounted over the
main shaft 156 to extend partially forwardly through the
`~ front plate 98 to form a bearing for rotation of the crank-
arm 112. A sidewardly projecting annular flange 206 at the
forward end of the bearing member 202 is bolted to a front
plate rearward face 208 by the bolts 166 which attach the
` 30 bracket 164 to the front plate 98. Several additional bolts
210 may also be used to attach the flange 206 to the front
plate 98. A rearwardly extending, tubular portion 212 of the
bearing member 202 is internally splined for receiving
portions of the anti-surge ratchet 200.
- 27 -
. -: , ~ , . . .
Forming the anti-surge ratchet 2~0, which is mounted
over the shaft assembly 104 rearwardly of the bearing member
202, is an externally splined, forwardly extending portion
214, which is slidingly disposed within the bearing portion
212, and a rear, sidewardly projecting flange 216. Disposed
around the overlapping tubular portions 212 and 214, respect-
ively, of the bearing member 202 and the anti-surge ratchet
200, the spring 204 biases or urges the anti surye ratchet
rearwardly towards the rotor hub 192.
Since the bearing member 202 is fixed to the front
plate 98 and because of the splined interconnection, the
anti-surge ratchet 200 is permitted only axially sllding
movement. Both the bearing member 202 and the anti-surge
ratchet 200 are internally configured to permit rotation of
the main shaft 156 therewithin.
Spaced 180 apart on the periphery of the anti-surge
ratchet flange 216 are two generally rectangular, radially
projecting ears or teeth 218 ~Figures 1, 5 and 7) for engaging
the rotor hub 192, as described below. Sides of the teeth
218 rearwardly converge at a small angle of, for example,
about 10. Formed orthogonally to a line through the teeth
218 and forwardly into a flat transverse rearward surface 220
of the flange 216, is a narrow, transverse ratchet recess 222.
Such recess 222 extends through a rotational axis 230 of
the anti-surge ratchet 200, and hence of the rotor 76 and the
rotor shaft assembly 104. Side edges of the recess 222 are
chamfered to enable smooth ratcheting disconnection.
Formed at the rear end of the rotor hub 192 is a
rigid, sidewardly projecting flange 232 through which the
30 rotor attaching bolts 196 are installed. Peripheral recesses
238 in the flange 232 continue, and thus form forward end
regions of, the rotor cavities 78. Extending forwardly from the
.
~ - 28 -
flange 232 and defining a forward hub recess 236, is a
tubular hub portion 240~ Formed into a forward edge 242 of
such portion 240 at 90 spaGing are four rectanyular recesses
244, with chamfered sides, configured for locking engagement
by the anti-surge ratchet teeth 218. When so engaged, the
rotor hub 192, and hence the entire rotor 76, is locked to
the front plate 98 against rotational moveme.nt, through the
anti-surge ratchet 200l to prevent any rotational driving
of the rotor 76 as shells are advanced thereinto from the
supply means 24.
Formed rearwardly into a hub recess bottom or forward
face 246 at 90 spacings are four generally rectangular radial
recesses 248 with chamfered sides, for ratcheting engagement
with the ratchet 198.
Disposed within the hub recess 236, between the
rotor hub face 246 and the anti-surge ratchet flange 216,
the ratchet 198 is nonrotatably, but axially slidably,
mounted over the shaft assembly 104. To provide for rotation/
ratcheting of the rotor and the anti-surge ratchet 200, the
generally cylindrical ratchet 198 is formed having ratchet
teeth on both axial ends.
Two diametrically opposed, forward teeth 254 formed on
the ratchet 198 project forwardly from a ratchet forward face
256 for driving engagement with the anti-surge ratchet recess
222 (Figure 7). Corresponding single side surfaces 258 of the
teeth 254 are beveled at an angle of about 45 in a direction
enabling the teeth 254 to slide or ramp out of the anti-surge
ratchet recess 222 in response to rotation of the main shaft
156, ~nd hence of the ratchet 198, in the shell transferring
~0 direction of Arrow "A".
29 -
., .
Formed on the ra~chet 198 to project rearwardly from
a ~atchet rearward face 260, are four equally spaced, rearward
teeth 262 configured for driving engagement with the rotor hub
recesses 248. Corresponding side surfaces 264 of all the rear-
ward teeth 262 are beveled oppositely to the surfaces 258 of
the forward teeth 254 at angles of about 45, and thus in a
direction enabling the rearward teeth to ramp out of the rotor
hub recesses 248 when the main shaft 156, and hence the rotor
198, is return rotated (direction of Arrow "C", Figures 1 and 9)
to enable rotatable decoupling of the rotor 76 from the shaft.
Relative axial lengths of the rotor 198 and the rotor
hub portion 240 are such that when the ratchet forward teeth
254 are fully received into the corresponding anti-surge
ratchet recess 222 and the ratchet rearward teeth 262 are
fully received into the rotor hub recesses 248, the anti-
surge ratchet teeth 218 are received, in rotor-locking
relationship, within a pair of the rotor hub forward edge
recesses 244.
In such double tooth-recess engagement condition, the
2a rotor 76 is non-rotatably locked, through the rotor hub 192,
the anti-surge ratchet 200 and the bearing 202, to the front
plate 98. Hence, shell transferring rotation of the rotor
76 cannot occur until the anti-surge ratchet 200 is forwardly
displaced sufficiently far to disengage the teeth 218 thereof
from the corresponding rotor hub recesses 248. Towards this
end, the rotor hub 192, the ratchet 198 and the anti-surge
ratchet 200 are relatively configured so that with the ratchet
rearward teeth 262 fully received into the corresponding hub
recesses 248, but with the ratchet forward teeth 254 out of
the corresponding anti-surge ratchet recess 222, and thus in
sliding contact with the anti-surge ratchet rearward surface
220, the anti-surge ratchet teeth 218 are out of locking
engagement with the corresponding rotor hub recesses 244.
- 30 ~
5~8
Several degrees of initial main shaft 156 rotatlon is
required to ramp the rotor forward teeth 254 out of the anti-
surge ratchet recess 222, thereby pushing the anti-surge
ratchet 200 forwardly out of locking engagement with the hub
19~ and unlocking the rotor 76 for shell transferring rotation.
Thus, the ratchet rearward teeth 262 and corresponding rotor
hub recesses 248 are relatively configured to permit initial
main~shaft rotation, for example, of about 7 degrees before
such ratchet teeth come into driving engagement with the
rotor hub 192.
Accordingly, as operatively described below, ,although
the rotor 76 (for the four cavity rotor illustrated) is
rotated in 90 incremental steps, the main shaft 156, and
hence the ratchet 198, is actually rotated (and must be
then counterrotated)through 97 by the first actuation means 64
;~ in order to provide the necessary rotor unlocking prior to
rotor rotation.
As shown in Figure 10, the first actuation means 64
includes a gas cylinder 272 having a piston 274 slidingly
disposed therein. Opposite ends of a rigid, intermediate
link 276 are pivotally connected to the piston 274 and to
the crankarm 112, respectively, by first and second transverse
pivot pins 278 and 280. Axial movement of the piston 274
in the cylinder 272 consequently causes, through the link
276, rotational movement of the crankarm 112 and, hence,
the main shaft 156.
Pressurized barrel gas, caused by firing of the
cannon 26, is fed into a gas chamber 282 in the cylinder
272, through an inlet 284 of the gas supply means 70, to
cause axial movement of the piston 274, in the direction of
Arrow "D", to rotate the rotor 76 in the shell advancing
direction (Arrow "A", Figures 1, 8 and 9).
Other portions of the gas supply means 70 include a
gas line 292 (Figures 2 and 10) interconnec~ing the inle~ 284
to the barrel 58. Conventional quick-disconnect means (not
shown) may be provided in the line 292.to permit easy removal
of the feeder portion 44 from the cradle 32, as may sometimes
be necessary. To accommodate cannon recoil and counterrecoil
relative to the feeding apparatus 20, end portions 2g4 of the
inlet 234 may be slidingly disposed, in gas sealing relation-
ship, in the line 292.
Return axial movement (direction of Arrow "E") of the
piston 274 after rotor indexing, is caused, through the mainshaft 156, the crankarm 112 and the link 276, by spring action
of the torsion bar 154.
Very rapid return rotation of the main shaft 156 is
desirable so that the rotor 76 may be locked, through the
rotor hub 198 and the anti-surge ratchet 200, against rotation
before shell advancement from the supply means 24 into the
rotor is completed to prevent rotor over travel. In addition,
such rapid return rotation is preferred so the second stage
feeding portion 62 may be unimpeded during operation by exert-
ing any return forces on the crankarm 116, as might slowadvancing of shells into the rotor 76.
To provide this rapid return.rotation, in addition
to the rotor shaft return rotation forces provided by the
torsion bar 154, conventional gas venting means (not shown)
are provided to vent high pressure gas in the cylinder chamber
282 when the rotor advancing stroke of the piston 272 is
completed.
3~.
- 32 -
Spring compressing movement of portions of the
second stage slide 80, is provided by a slide actuator 298,
which forms part of the second actuation means 66 and is con-
nected to the crankarm 116 (Figure 11). Conventional means
300, mounted o the rear surface 114 of the rear plate 100,
are provided for converting rotary movement o the crank 116
into linear movement of the slide actuation 298, and hence
portions of the slide 80. Thus, rotational movement of the
crank 116 in the rotor indexing direction of Arrow "A", causes
linear outward spring compressing movement of the slide actuat-
or 298 ~Arrow "F"), for slide cocking purposes. Conversely,return rotation (direction of Arrow "C") of the crankarm
116 causes return movement (direction of Arrow "B") of the
slide actuator.
Comprising the slide 80 are a fixed track 302 (Figures
1 and 12) mounted to, or formed as a part of, the drum segment
42; a linearly reciprocating, shell advancing portion 304, and
spring means 306. Interconnecting the track 302 and the recip-
rocating portion 304, the spring means 306, which may comprise
a side-by-side, pair of elongate compression springs 308,
urge or bias the reciprocating portion towards the rotor 76
(in the direction of Arrow "B").
Pivotally connected to the reciprocating slide portion
304 are pairs of transversely spaced apart, spring loaded
first shell advancing pawls 310. The number of pairs of the
first pawls 310 corresponds to the number of the shells 22
which can be held in the drum segment 42, spacing of pairs
of the pawls 310 corresponding to spacing between the shells
(or shell positions) in the segment.
` ?
- 33 -
Spring mounting of the pairs of first pawls 310 is
such that when the reciprocating portion 304 is pushed out-
wardly in the direction of Arrow "F" by the slide actuator
298, each of the pawls is upwardly deflected and rides over
the adjacent shells, stroke of the reciprocating portion 304
being equal to, or only slightly greater than, a single shell
spacing in the segment. During outward movement of the slide
portion 304, after riding over the adjacent shell, the first
pawls 310 pivot back downwardly into shell engaging position.
Thus, on the return stroke of the sliding portion 304, caused
by the spring means 306, all the she~ls 22 in the segment 42
are advanced by the pawls 110 one position towards the rotor
76, the shell closest to the rotor being thereby advanced or
transferred into the adjacent one of the rotor cavities 78.
Backing up of the shells 22 in the segment 42, as the
slide portion 304 is moved outwardly, is prevented by pairs
of second, spring loaded pawls 318 t which are mounted to upper
regions of the below adjacent track 302~ These pairs of second
pawls 318, which correspond in number and spacing to the number
and spacing of the first pawls 110~ and hence of shell
positions in the segment 42, are configured to deflect or
retract downwardly under the shells 22, as the reciprocating
slide portion 304 advances the shells towards the rotor 76.
However, the extended second pawls 318 prevent movement of
the shells away from the rotor 76, as might otherwise be
caused by outward movement of the slide portion 304.
To enable charging of the cannon 26 prior to firing,
by feeding two of the shells 22 into an initially empty
rotor 76, an end 320 of the slide actuator 298 remote from
3~ the slide portion 304, is preferably configured for driving
engagm~nt by charging means (not shown). Starting with an
empty rotor 76, two cyclings of the slide actuator 304 by the
charging means advances two shells 22 from the segment 42 into
adjacent rotor cavities 78, as is necessary for firing.
- 34 -
Searing up control of the bolt 30, as more particularly
described below, may be provided by first and second shell
sensing elements 324 and 326, respectively, (Figures 3, 4, 11
and 17) which may, for example, be of conventional microswitch
or of Hall Effect type. As shown the first shell sensing
element 324 is mounted, through the second feed lip member 88,
to sense presence of a shell in the pick up position 48~ The
second shell sensing element 326 is mounted through the fixed
track 302, to sense presence of a shellis in the next-to-the-last
(No. 9) shell feeding position relative to shell transferring
into the rotor 76. In response to a first, simultaneous
sensing of absence of shells by both the elements 324 and 326,
searing up of the bolt 30 is signalled or initiated and firing
ceases, as described below, with two shells in the rotor.
Accordingly, no charging before a next firing is required.
At high bolt velocities, such as those associated
with high firing rates enabled by the two stage shell feeding
apparatus 20, high impact stresses can be caused when the
bolt 30 picks up shells indexed into the pick up position 48
for stripping and loading. Since such impact is on a base 322
of the shell 22 (Figure 6), high impact stresses can, if
sufficiently great, cause detonation of the shell being picked
up with usually disastrous results. Less severe impact stresses
may damage or deform a lower, shell base impact region 334
sufficiently to cause problems with shell casing extraction
and ejection after firing. This results from the shell base
impact region 334 being subsequently moved downwardly, as the
shell 22 is loaded into the breech 52, into gripping engage-
ment by a conventional bolt mounted extractor 336 which,
3a during shell casing ejection after firing, also functions as
a hinge point about which the ejected casing pivots. Impact
damage to the base region 334 affects ability for the extractor
to properly grip the shell base 332.
;~ i
- 35 -
To eliminate shell base impact damage on pick up,
the shell accelerator means 92 accelerates the shell 22 in
the pick up position 48 to a velocity approximately equal to
bolt velocity before bolt-shell engagement occurs. Comprising
the accelerator means 92 is a housing 338 which is mounted to
the rear plate surface 114 and in which the shell accelerator
member 138 is pivotally mounted on a transverse pivot pin 340.
Spring means 342 are provided between the housing 338 and the
accelerator member 138 to urge the accelerator member into a
shell engaging, intermediate position shown in Figure 6, while
permitting the accelerator member to pivot rearwardly and
upwardly ~direction of Arrow "H") about the pivot pin 340 in
response to engagement by the recoiling bolt 30. Conventional
spring loaded detent means 344 are provided for releasably
retaining the accelerator member 138 in the intermediate
position.
A forward, generally arcuate shell base engaging sur-
face 346 of the accelerator member 138 is configured to causean increasing velocity of the shell 22 during initial shell
stripping. This enables controlled engagement between the
accelerator surface 346 and the shell base 332 to be maintained,
without bouncing, as the accelerator member 138 is pivoted
forwardly (direction of Arrow "J") and the shell 22 is pushed
forwardly (direction of Arrow "K").
Curvature of the accelerator surface 34~, which can be
rigorously developed by laying out a sequence of accelerator
member and shell posi~ions, can be closely approximated, to
the extent normally required for satisfactory operation, by
a single radiusD
3n
ji` ~
- 36 ~
A lower, central region 348 of the accelerator member
138 is notched to permit passage of the bolt mounted rammer
134. Function of the rammer 134 is to prevent bolt underride
of the shell 22 being picked up from the pick up position 48
in the event the accelerator member 138 malfunctions or breaks.
Under ordinary operation, the shell 22 is sufficiently moved
ahead by bolt impact on the accelerator member 138 that by the
time the bolt 30 reaches the shell, the shell base region 334
will have moved down into a bolt engagement position not requir-
ing use of the rammer 134. Spring loading of the rammer 134
towards the upwardly extended, shell pick up position shown
enables the rammer to pivot downwardly (direction of Arrow
"L") as the bolt 30 recoils rearwardly under shells in the
pick up position 48.
Side regions of the accelerator member surface 346
may be configured, in a manner not shown, for causing rear-
ward pivoting of the accelerator member 138 to the intermediate
position, from the forwardly pivoted position, in response to
. rotational indexing of the rotor 76.
As an alternative to the transversely pivoted accelerator
member 138 shown, a correspondingly configured accelerator member
may be pivotally mounted on a vertically disposed (as seen in
Figure 6) pivot pin in a manner not shown.
It is to be appreciated that for lower firing rates not
resulting in damaging shell impact stresses, the accelerator
- means 92 may be eliminated, in which case, the rammer 134 is
then operative for forwardly strippiny the shell 22 from the
pick up position 48.
As is typical of most automatic cannon, the longitud-
inal axis 54 through the shell pick up position 48 is parallel
to, but offset from, (above in Figure 13) the barrel bore axis
56 a radial distance "r", which may, for example, be abaut
equal to a maximum shell diameter "d". Such shell offse~ting
is necessary to enable moving a shell into the pick up position
- 37 -
.
4~ sufficiently rapidly to assure availablility of a shell
for picking up by the bolt 30 on counterrecoil, while still
permitting relatively unimpeded bolt recoil past the pick up
position. In practice, moving shells even a short distance
inwardly towards the bore axis 56 after the rotor indexing
has proven to be very difficult and unreliable.
As a consequence of such off-bore axis positioning of
the shell pick up position 48, shells stripped or rammed for-
wardly from the rotor 76 are required to move in a generally
S-shaped feed path, indicated by the reference number 352
(Figure 13), forwardly and inwardly towards the breech 52.
When the bolt stroke is short and bolt velocity is
high, to achieve high cannon firing rates otherwise enabled
by the two stage shell feeding apparatus 20, the feed path
352 is relatively sharply curved, since rearward positioning
of the rotor 76 from the breech 52 is necessarily minimized.
For example, for the exemplary cannon 26, a distance, "1",
between a projectile nose end 354 of shells 22 in the pick up
position (Figure 13) and a rear face 358 of the breech 52
2~ surrounding a breech opening 360 is between 25-35 percent of
overall shell lenght "L", depending upon breech recoil/
counterrecoil position.
In fast firing automatic guns having high forward
shell feeding velocities and short shell feed paths, cor-
responding to the path 352, problems frequently can occurin feeding shells from an offset pick up position into the
breech. Magnitud and incidence of such problems are
increased when breech recoil/counterrecoil mo~ement causes
the feed path length to vary from one firing to another.
If, as an illustration, movement of the stripped shells is
not adequately controlled along the feed path, the projectile
may completely miss the breech opening and impact the sur-
rounding breech surface. Ordinarily this causes gun jammingand may cause explosion of the shell. Or, when the pro-
- 38 -
jectile strikes the breech surface onl~ a glancing blow before
entering the breech opening, the projectile may be damayed to
an extent adversely affecting weapon system effectiveness,
particularly if the projectile is of a fused type.
Since feeding of shells 22, along the feed path 352,
from the pick up position 48 into the breech 52, is an im-
portant adjunct to transferring shells from the supply means
24 into the pick up position, and to avoid or substantially
reduce shell feed path related problems, control of shells
moving along the feed path is provided. Such feed path con-
trol is enabled by configuring inner walls 362 of the rotor
cavities 78, the feed lip members 86 and 88 and the deflector
means 90 so that guiding engagement is maintained with the
shells as the shells transverse the feed path 352 and until
the shells are sufficiently far into the hreech 52 that con-
trol is no longer needed.
Cooperating with the rotor cavity walls 362, feed
lip members 86 and 88 and the deflector means 90 to provide
shell control along the feed path 352 are means defining a
2Q U-shaped, shell base receiving slot or recess 370 at a forward
face 372 of the bolt 30. The bolt face recess 370 is open
in upper regions to enable entrance of the shell base 332.
Lower, inner recess wall regions 374 stop inward movement of
the shell base when the shell is generally aligned with the
barrel bore axis 56. In addition, means defining a small,
arcuate recess 376 inside the breech 52, in a shell casing
shoulder abutting portion 378 thereof, mav be provided for
projectile nose end 354 clearance. The recess 376 is formed
in lower regions (as seen in Figure 13) of the breech where
projectile nose ends 354 of shells 22 being loaded might
otherwise hit a breech inner wall 380.
- 39 -
~ ~f`'~
Depending, for example, upon such factors as the gun
firing rate, the pick up position offset distance "r" and
the distance "1" between the shell end 354 and the breech 52,
either, or both, the breech recess 376 and the shell deflection
means 90 may be unnecessary for providing adequate shell feed
path control.
Configuration and contour of the rotor cavity wall
362, the feed lip members 86 and 88, the deflector means 90
and the breech recess 376 are determined, as shown in Figure
13, by plotting or laying out a sequence of desired intermediate
shell positions 386 between the pick up position 48 and a fully
chambered shell position 388. This sequence of shell positions,
in effect, defines the feed path 352.
After the shell feed path 352 has been so defined, the
cavity walls 362, the feed lip members 86 and 88 and the de-
flector means 90 are correspondingly configured so that, as
shown in the various spaced apart cross sections of Figure 14,
shell guiding engagement is maintained until a shell projectile
390 is well inside the breech 52.
Contours of the rotor cavity walls 362 conform gener-
ally to those of the associated shells 22, so the shells 22
are relatively closely contained in the cavities 78 d~ring
rotational transporting. However, to reduce length of the
feed path 352 by enabling the forwardly stripped shells 22
to be deflected towards the barrel bore axis 56 at a greater
angle than would otherwise be possible, rearward cavity wall
regions 392, 362 (Figure 13) are gradually lon~itudinally
bowed inwardly toward the axis 230 of the rotor. Accordingly,
as the shells 22 are stripped forwardly, and a cavity shoulder
394, corresponding to a necked down shoulder or projectile
retaining region 396 of the shells 22, deflects the projectile
nose end 354 inwardly towards the barrel bore axis 56 (Figures
14(a) - (c)), the shell base 332 is enabled to move slightly
outwardly away from the bore axis into the bowed or recessed
~; ~ 40 -
cavity region 392, 36Z (Figure 13). The bowed cavitv region
392, 362 provides a guiding surface for smooth movement of
the shell from the rotor cavity to the cannon firing chamber.
- As shell stripping continues, upper surfaces of the
shells 22 are guided along cavitv edges or corner regions
398 (Figures 14 (d) and (e)) of smaller radius cavity
regions, which correspond to shell projectile radius. During
such shell stripping movement, lower surfaces of the shells
22 are guided along opposing side edges 400 of the feed lip
member intermediate gap region 140.
Downwardly and forwardly sloping lower surfaces 402
(Figures 6 and 13) of the deflector means 90 are configured
so that, as forward and inward shell movement continues,
engagement between such surfaces and the shell shoulder 396
causes the shell base 332 to pivot inwardly towards the
barrel bore axis 56 and into the bolt face recess 370. At
this point, the shell base 332 passes freely downwardly
between the feed lip members 86 and 88 in the gap region
142 (Figure 14 (f)). Lower central regions of the deflector
means 90 are cut away to provide clearance for the shell
xammer 134.
As the shell 22 pivots into alignment with the barrel
bore axis 56, with the base 332 moving into full engagement
with the bolt face recess 370, the projectile nose end 354
may pass through the breech block recess 376. When one of
the shells 22 is completely chambered in the breech 52, con-
tinued forward movement of the bolt carrier 404 associated
with the bolt 30 drives a firing pin 406 into firing engage-
ment with the shell (Figure 6).
- 41 -
It is to be appreciated that feeding of the shells 22
from the supply means 24 into the shell pick up position 48
in time for picking up by the bolt 30 on bolt counterrecoil,
and subsequently controlling movement of the shells from the
pick up position into the breech 52 for firing involve two
related, but nevertheless relatively separable operations.
Accordingly, the two stage feeding apparatus 20 can be em-
ployed to advantage even when no subsequent feed path control
is required or other feed path control means are provided.
Conversely, the described shell feed path control can be
utilized on other types of guns not requiring the two stage
feeding.
OPERATION
-
Operation of the two stage shell feeding apparatus 20
with shell acceleration and feed path control is generally
apparent from the foregoing description of the apparatus.
Assume the bolt 30 is initially seared up rearwardly
of the rotor 76 and a shell 22 is indexed into the pick up
position 48. When unseared, the bolt 30 travels forwardly,
driven by conventional recoil springs (not shown), and im-
pacts the accelerator member 138 (Figure 6) which, in turn,
starts accelerating the shell forwardly from the pick up
position 48 so that when the bolt 30 "catches up" with the
shell base 332, impact therewith is reduced because of for-
ward shell velocity.
After ramming the shell forwardly and inwardly along
the feed path 352 (Figure 13) into the breech 52, the shell
22 is fired by the bolt carrier mounted firing pin 406. As
the projectile starts moving down the barrel 58, high pressure
gases caused by propellant ignition, are directed by the gas
supply means 70 to the chamber 282 (Figures 2 and 9) of the
first actuation means 64, thereby driving the piston 274
outwardly (direction o Arrow "D"). In turn, the moving
piston 274 causes rotation of the crankarm 112 and, hence,
- 42 -
~ 5~
of the main shaft 156 and the ratchet 198 (direction of
Arrow "A", Figures 2, 7 and 15).
During the initial several degrees, for example,
seven degrees of the main shaft and ratchet rotation, as
the forward r~tchet teeth 254 ramp out of the anti-surge
ratchet recess 222 (Figure 15(a)), the ratchet 198 pushes
the anti-surge ratchet 200 forwardly (direction of Arrow
"K"), compressing the spring 204. As the anti-surge ratchet
200 is pushed forwardly in th is manner by rotation of the
main shaft 156 and the ratchet 198, the anti-surge ratchet
teeth 218 are withdrawn from engagement with the corres-
ponding rotor hub recesses 244. This unlocks the rotor 76
for 90 shell transferring rotation (direction of ~rrow "A")
during the remaining outward travel of the gas piston 274
and rotation of the crankarm 112 and the main shaft 156.
After the rotor unlocking, the ratchet teeth 254 slide along
the anti-surge ratchet rear surface 220.
Assuming one of the shells 22 was initially loaded
into the rotor cavity 78 next adjacent to the pick up
position 48 in the direction of rotor rotation, subsequent
90 rotor rotation indexes such shell into the shell pick
up position before or during initial bolt recoil movement
from the breech 52.
At the same time that the rotating crankarm ll2 causes
rotational indexing of the rotor 76, the crankarm 116,
associated with the second actuation means 66 and fixed to
- the main shaft 156 for simultaneous rotation with the crank-
arm 112, causes outward, spring compressing movement of the
slide portion 304 (direction of Arrow "F", Figures 1 and 11)
through the actuating member 298.
- 43 -
S~s~
After complete (97) rotation of the main shaft 156
by the crankarm 112, barrel gas is vented from the gas chamber
282 and the torsion bar 154 causes ranid rerotation (direction
of Arrow "C", Figure 15(b)) of the main shaft and, hence,
of the ratchet 198. However, reverse rotation of the rotor
76 (including the rotor hub 192) is prevented by the anti-
back up means 130 (Figure 9) which engage peripheral regions
of the rotor 76. Return rotation of the main shaft 156 is
enabled by the rear ratchet teeth 262 ramping up out of the
corresponding rotor hub recesses 248, thereby pushing the
ratchet 198 and the anti-surge ratchet 200 forwardly (direction
of Arrow "~") against the spring 204. During return rotation
of the main shaft 156 and the ratchet 198, the ratchet rear
teeth 262 slide along the rotor hub recess bottom 246.
Upon completion of q7 return rotation of the main
shaft 156 and the ratchet 198, the ratchet teeth 262 and 254
drop into the corresponding rotor hub and anti-surge ratchet
recesses 248 and 222. When this occurs, the anti-surge
ratchet 200 is driven rearwardly by the spring 204, moving
the anti-surge ratchet teeth 218 back into rotor locking
engage~ent with the rotor hub recesses 244.
This main shaft rerotation and consequent rotor
locking occurs at least before complete transfer of a next
shell from the magazine segment 42 into the rotor 76,
thereby preventing continued, normal direction rotation of
the rotor, as might otherwise be caused by pushing shells
into the rotor cavities.
In response to the slide portion 304 being pushed
outwardly (direction of Arrow "F", Figures 1 and 11), the
pawls 310 mounted thereto ride up over corresponding ones
of the shells 22, outward movement of the shells 22 in the
segment 42 being prevented by the pawls 318 mounted to the
fixed member 316. Outward movement of the slide portion
~ 304 compresses the slide springs 308. Consequently, ~hen
'..~
- 44 -
the slide actuator 298 is returned (direction of Arrow "~")
to its initial position by the crankarm 116, the springs
308 push the slide portion 304 back towards its initial
position (also direction of Arrow "B"). As the slide portion
304 is returned, the attached pawls 310 push the shel~s 22
one shell position in the segment 42, thereby advancing the
shell in the number 10 position ad~acent the rotor 76 into
the indexed, empty rotor cavity 78. During such shell
advancing, the shells 22 deflect the fixed member pawls 318
downwardly to permit shell passage thereover.
As mentioned above, the first detent means 120
(Figure 8) prevents overrotation of the rotor 76 during
the first stage feeding operation by abutting the shell
22 indexed into the shell pick up position 48. Portions
of the second detent means 122, which prevent the adjacent
(end) shell 22 in the segment 42 from moving into rotor
contact during first stage rotor turning, deflect or retract
to enable shell advancing into the rotor cavity 78 during
the second stage feeding operation by the slide portion 304.
During forward, counterrecoil bolt travel, the shell
22 now indexed into the pick up position 48 is stripped
forwardly from the rotor 76 and moved along the feed path
352, as depicted in Figure 13, into the breech 52 for
firing by the bolt carrier mounted firing pin 404. Con-
ventional means, not shown, are provided for locking the
bolt 30 to the breech 52 during firing.
Operation of the apparatus 20 is further su~mari~ed
diagrammatically in Figures 16 and 17 in which the drum
segment 42 is shown initially holding ten shells 22,
30` numbered 1 through 10.
.,
- 45 -
J~
- When the associated cannon is to be fired from an
empty rotor condition, a double charging operation is required,
during which the slide actuator 298 is mechanically cycled
twice by conventional charging means (not shown). As the
actuator 248 is pushed outwardly a first time (direction of
Arrow "F", Figuxe 16(a)), the empty rotor 76 is indexed one
cavity position (direction of Arrow "A") and the sliding
portion 304 is pushed outwardly (direction of Arrow "F").
As the slide springs 308 return the sliding portion 304
(direction of Arrow "~", Figure 16(b)), to its initial position,
the number "1" shell is advanced into the adjacent one oE the
rotor cavities 78.
Charging the actuator 298 a second time (Figure 16(c)),
rotates the rotor 76 another 90, to index shell No. 1 into
the shell pick up position 48 and pushes the sliding portion
304 outwardly again. Upon return movemen~ of the sliding
portion 304, shell No. 2 is advanced into the ad~acent one
of the rotor cavities 78 (Figure 16(d)). At this point,
the cannon 26 is ready for firing, assuming the bolt 30 is
already seared up rearwardly of the pick up position 48.
Upon unsearing, the bolt 30, which is driven forwardly
by conventional drive means (not shown), picks up shell No. 1
from the pick up position 48 (Figure 16(e)), then pushing the
shell forwardly into the breech and firing it. Immediately
in response to pressurized gases caused by firing shell No.
1, the rotor is rotated 90 (Arrow "A", Figure 16(f)) to
index shell No. 2 into the pick up position 48. Simultaneously,
the sliding portion 304 is pushed outwardly (Arrow "F") com-
pressing the slide springs 308. As the sliding portion 304
returns (Arrow "B"), shell No. 3 is advanced into the
adjacent one of the rotor cavities 78 (Figure 16(g)). By
the time shell No. 3 is advanced into the adjacent rotor
cavity 78, shell No. 2 will ordinarily already have been
picked up by the counterrecoiling bolt for firing.
- 46 -
'
Since in combat situations the time required for the
above described double charging operation may be critical,
stopping of firing by bolt searing, for example, at the end
of the burst, with the apparatus 20 in a fully charged con-
dition with two shells left in the rotor 76 is necessary
for an effective weapons system. Then, for a next firing
all that is required is unsearing of the bolt 30.
Figure 17 depicts the se~uence by which ceasing
firing with the apparatus 20 in the charged condition is
accomplished. Assuming shell No. 7 has just been fired, in
response thereto, the rotor 76 is rotated 90, indexing shell
No. 8 into the pick up position 48 (Figure 17(a)). The last
shell No. 10 now occupies a next~to-the-last shell position
in the segment 42; that is, the shell position initially
occupied by shell No. 2. At that instant, as for corres-
ponding instants associated with previous shell firings, the
sensing means 324 and 326 still sense, respectively, presence
of a shell (No. 8) in the pick up position 48 and a shell (No.
10) in the next-to-the-last segment position.
However, during the second stage portion of the
feeding operation (Figure 17 (b)), after the bolt 30 strips
shell No. 8 from the pick up position 48, shell No. 9 is
completely transferred by the slide 80 into the rotor 76,
thereby advancing shell No. 10 from the next-to-the-last
segment position into the last segment position. Now, both
the sensors 324 and 326 simultaneously sense no shells in
either the pick up position or in the next-to-the-last
segment position. In response, the sensors 324 and 326
provide electric signals to searing means (not shown)
directing searing up of the bolt 30 the next time the bolt is
at the searing position. The bolt is however, still moving
forwardly in counterrecoil at this time with shell No. 8. -
- ~7 -
.
In response to firing shell No. 8, the ro~or 76 is
rotated 90 (Figure 17(c)) to index shell ~o. 9 into the
pick up position ~8. Although the bolt 30 then sears up on
counterrecoil, leaving shell No. 9 in the pick up position
48, shell No. 10 is still advanced into the rotor 76 (Figure
17(d)) by the returning sliding portion 304. The feeding
apparatus 20 is now in the fully charged condition of Figure
16(d) with the bolt 30 seared up, and will be ready for
firing again when a subsequent drum segment 42a (Figure 17(e)),
containing a second group of ten shells numbered 1' - 10',
is indexed into rotor feeding position.
It is to be appreciated, however, that whenever firing
is interrupted during a burst, as determined by drum segment
capacity, or if a continuous, belt-type shell supply were
alternatively used, firing would automatically cease with
two shells in the rotor 76 and the gun ready for firing even
though there was no simultaneous sensing of empty positions
by the sensors 324 and 326.
It is further to be appreciated, that when searing
up is accomplished in the above described manner for ten
shell segments 42, only eight shells are fired from the first
segment, the ninth and tenth shells remaining in the rotor
76 after searing up. In subsequent firings, however, full
ten shell bursts can be fired.
At the end of firing, the two shells 22 remaining
in the rotor 76 may be removed, for example, by operation
of the charging means or by opening the cradle 32 (Figure
` 2) and pivoting open the feeder portion 44 and manually
removing the shells from the rotor.
- 48 -
s~
Figure 18 depicts, by way of specific illustrative
example, time sequence operation of the two stage feeding
apparatus 20, showing relative displacement of the bolt 30
(Figure 18(a)), the rotor 76 (Figure 18(b)) and the shell
sliding portion 304 (Figure 18(c)), all plotted against a
common time axis calibrated in milliseconds after firing.
The plots of Figure 18 were experimentally obtained for a
35mm automatic cannon having a bolt assembly mass of about
20 pounds, an individual shell mass of about 3 1/2 pounds and
a firing rate of approxiately 600 rounds per minute or 100
milliseconds per round. A ten round capacity drum segment
42 was used. Stroke length of the bolt (corresponding to
the bolt 30) and of the sliding portion (corresponding to
the sliding portion 304) were ahout 22 inches and 2.5 inches
respectively. Rotor indexing was 90 per shell fired.
As shown in Figure 18(a), unlocking of the bolt 30
occurs during a time interval of about 5-15 milliseconds
after firing, thereby enabling recoil movement of the bolt
to start about 12 milliseconds after firing. Bolt-buffer
50 interaction occurs between about 47-53 milliseconds after
firing. That is, the recoiling bolt impacts the buffer 50
about 47 milliseconds after firing, compressing spring
elements in the buffer; at about 53 milliseconds after
firing the bolt leaves the buffer in counterrecoil. Shell
acceleration (by the acceleration means 90) occurs between
about 55-59 milliseconds after firing, with shell ramming
or movement along the feed path 352 occuring from about
59 to 95 milliseconds after firing.
From Figure 18(h) it is seen that rotor rotation
starts only about 5-6 milliseconds after firing, and 90
rotation thereof is completed only about 17-18 milliseconds
after iring - at a time when the bolt 30 has traveled only
a few inches in recoil and nearly 40 milliseconds before
the bolt counterrecoils ~o the shell acceleration position
_ ~9 _
54~
(Figure 18(a)). Return ratchet rotation of the main shaft
156 and gas venting is completed by about the time the bolt
30 impacts the buffer 50.
Outward, cocking movement of the sliding portion 304
is seen from Figure 18(c) to occur simultaneously with rotor
rotation (Figure 18(b)), as is expected because of the two
crankarms 112 and 116 are fixed to the main shaft 156
(Figure 6) to rotate in unison.
Shell transfer from the segment 42 into the rotor
76 is seen from Figure 18(c) to be dependent upon the number
of the shells 22 required to be simultaneously advanced the
single shell position.
As is expected, complete transferring of one of the
shells 22 from the segment 42 into the rotor 76 is slowest
when the shell is the first shell of a ten shell segment.
That is, shell transferring from the segment 42 into the
rotor 76 is slowest, being completed about 68 milliseconds
after firing, when ten shells, having a total mass of about
35 pounds, must be advanced by the slide springs 308. In
contrast, when only one shell (the No. 10 shell) remains
in the segment 42, transferring of such shell into the
rotor 76 is completed about 43 milliseconds after firing.
In any event, it can be seen from Figures 18(b) and
(c) that the rapid, first stage, rotor rotation of a shell
into the pick up position 48, by about 17-18 milliseconds
after firing, leaves about 82-83 milliseconds, or over four
fifths of the cycle, for the second stage shell feeding.
Thus, for example, Figure 18(c) indicates that with
ten round segments, wherein both stages of the feeding cycle
are completed about 68 milliseconds after firing, the two
stage feeding apparatus 20 has potential for feeding shells
from the segment 42 into the pick up position 48 at firing
rates approximately 50 percent higher, or at firing rates
about 900 rounds per minute.
_ 50 -
5~
It should be appreciated that although the rotor
76 is shown and described as having four cavities 78 and
as being rotatably indexed through 90 during each feeding
cycle, different gun and shell supply arrangements,
particularly if the feeding apparatus 20 is adapted for
use with preexisting weapons systems, may dictate different
rotational angles and different numbers of rotor cavities.
For example, for some weapons systems, a three cavity rotor
indexed through 120 may be more advantageous.
Since, however, rotational indexing speed of the
rotor 76 is dependent to a large extent on rotational angle
and mass to be rotated, including that of the shell or
shells being rotated, percentage division of time betwaen
first and second stage shell feeding may vary from the illus-
trative example shown according to rotor configuration.
Although there has been described above a specific
arrangement of two stage shell feeding apparatus with shell
acceleration and feed path control for automatic cannon and
the like, in accordance with the invention for purposes of
illustrating the manner in which the invention may be used
to advantage, it will be appreciated that the invention is
not limited thereto. Accordingly, any and all modifications,
variations or equivalent arrangements which may occur to
those skilled in the art should be considered to be within
the scope of the invention as defined in the appended claims.
- 51 -
' '
