U.S. patent number 3,690,218 [Application Number 05/000,928] was granted by the patent office on 1972-09-12 for breech mechanism for automatic or semi-automatic guns.
Invention is credited to Bernard Maillard, 14, Chateau Banquet.
United States Patent |
3,690,218 |
|
September 12, 1972 |
BREECH MECHANISM FOR AUTOMATIC OR SEMI-AUTOMATIC GUNS
Abstract
The breechblock slides in a casing which in turn slides
non-rotatably in the breechcase. Mechanical means transform into
rotary movement of the breechblock at least a part of the
longitudinal movement of the casing, relative to the breechblock,
when the breechblock has substantially reached its front closing
position, for locking the breechblock by co-operation between the
barrel and locking lugs formed on the breechblock. At least a
portion of each one of (a) the external surface of the locking
lugs, (b) the external surface of the casing and (c) the internal
surface of the breechcase, lies on a common geometrical cylinder of
revolution such that the breechblock is guided along the internal
surface of the breechcase by the engagement both of the external
surface of the lugs and of the external surface of the casing on
the internal surface of the breechcase.
Inventors: |
Bernard Maillard, 14, Chateau
Banquet (Geneva, CH) |
Family
ID: |
26640010 |
Appl.
No.: |
05/000,928 |
Filed: |
January 6, 1970 |
Current U.S.
Class: |
89/185 |
Current CPC
Class: |
F41A
19/30 (20130101); F41A 25/12 (20130101); F41A
3/66 (20130101); F41A 3/26 (20130101); F41A
15/14 (20130101); F41A 9/49 (20130101); F41A
11/00 (20130101); F41A 15/16 (20130101) |
Current International
Class: |
F41A
11/00 (20060101); F41A 15/14 (20060101); F41A
15/16 (20060101); F41A 25/00 (20060101); F41A
15/00 (20060101); F41A 19/30 (20060101); F41A
9/00 (20060101); F41A 3/66 (20060101); F41A
25/12 (20060101); F41A 9/49 (20060101); F41A
19/00 (20060101); F41A 3/26 (20060101); F41A
3/00 (20060101); F41d 003/06 () |
Field of
Search: |
;42/16R,16A,17A,18A,19A,20A,25,25A ;89/171,172,184,185 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Stephen C. Bentley
Attorney, Agent or Firm: Larson, Taylor & Hinds
Parent Case Text
REFERENCE TO RELATED APPLICATIONS
This application discloses and claims subject matter disclosed and
claimed in my earlier applications, Ser. Nos. 717,621, filed Apr.
1, 1968 and issued as U.S. Pat. No. 3,507,187 on Apr. 21, 1970 and
U.S. application Ser. No. 810,863, filed Oct. 2, 1968 and issued as
U.S. Pat. No. 3,561,148 on Feb. 9, 1971, this latter application
being a division of my earlier application, Ser. No. 717,524, filed
Apr. 1, 1968 and issued as U.S. Pat. No. 3,447,418 on June 3, 1969.
Claims
I claim:
1. In a breech mechanism of the type for use with an automatic or
semi-automatic gun comprising a breechblock mounted in a breechcase
having a barrel cooperating therewith, said breechblock adapted to
be locked by cooperation between the barrel and locking lugs formed
on the breechblock, means at the forward end of the breechblock for
receiving the rear end of cartridges to be fired, a casing
non-rotatably mounted in the breechcase about the breechblock for
longitudinal sliding movement, and means for locking the
breechblock by transforming into rotary movement of the breechblock
at least a part of the longitudinal movement of the casing,
relative to the breechblock, which relative movement takes place
when the breechblock has substantially reached its front closing
position at which it closes off the rear end of the barrel, the
improvement wherein: the said means at the forward end of the
breechblock comprises a cup-shaped recess, and said locking lugs
are formed on and spaced apart about the periphery of the exterior
of the breechblock, a first longitudinal recess formed on the
exterior surface of the breechblock in a first space between the
locking lugs, for receiving a cartridge extracting means carried by
the breechblock, and a second longitudinal recess formed in the
exterior surface of the breechblock in a second space between the
lugs which is opposed from the first longitudinal recess, the depth
of the second longitudinal recess into the breechblock being
sufficient so that the second longitudinal recess intersects the
said cup-shaped recess at the forward end of the breechblock to
provide a passage for a cartridge ejector carried by the
breechcase, said extracting means comprising an extractor member
held in place to engage a cartridge by a heel part which pivotably
engages a front part of the breechblock, and including a leafspring
mounted in said first recess, the rearward end of this leaf-spring
being held against the breechblock and the forward end of the
leaf-spring being biased outwardly against said heel part, thus
maintaining the extractor member in place both radially and
longitudinally relative to the breechblock.
2. A breech mechanism as claimed in claim 1 wherein the angular
spacing measured between the adjacent lugs defining said first
space is twice the average angular spacings measured between the
remaining adjacent lugs.
3. A breech mechanism as claimed in claim 2 wherein said first
space is (2 (360.degree.))/(2n+1) and at least one of the remaining
spaces is 360.degree./2n+1, wherein "2n" equals the number of lugs
extending about the periphery of the breechblock.
4. In a breech mechanism of the type for use with an automatic or
semi-automatic gun comprising a breechblock mounted in a breechcase
having a barrel cooperating therewith, said breechblock adapted to
be locked by cooperation between the barrel and locking lugs formed
on the breechblock, means at the forward end of the breechblock for
receiving the rear end of cartridges to be fired, a casing
non-rotatably mounted in the breechcase around the breechblock for
longitudinal sliding movement in the breechcase and between a
forward position and a rearward position, relative to the
breechblock, means for forming a generally annular and generally
fluid tight chamber between the outside of the breechblock and the
inside of the casing in either of said forward or rearward
positions of the casing relative to the breechblock, and means for
locking the breechblock by transforming into rotary movement of the
breechblock at least a part of the longitudinal movement of the
casing, relative to the breechblock, which relative movement takes
place when the breechblock has substantially reached its front
closing portion at which it closes off the rear end of the barrel,
the said means at the forward end of the breechblock comprises a
cup-shaped recess, said locking lugs being formed on and spaced
apart about the periphery of the exterior of the breechblock, a
first longitudinal recess formed on the exterior surface of the
breechblock in a first space between the locking lugs, a cartridge
extracting member carried by the breechblock in said recess, and a
spring located in a groove formed onto the exterior surface of the
breechblock and having one end fixed to the breechblock within the
fluid tight chamber and biased radially outwardly of the
breechblock axis for urging the cartridge extracting member to its
cartridge holding position, said recess guiding said extracting
member to prevent lateral movement thereof relative to the
breechblock, and a second longitudinal recess formed in the
exterior surface of the breechblock in a second space between the
lugs which is opposed from the first longitudinal recess, the depth
of the second longitudinal recess into the breechblock being
sufficient so that the second longitudinal recess intersects the
said cup-shaped recess at the forward end of the breechblock to
provide a passage for a cartridge ejector carried by the
breechcase.
5. A breech mechanism as claimed in claim 4 said breechblock
including a raised annular enlargement formed thereon in the fluid
tight chamber, said enlargement engaging forward and rearward walls
of the fluid tight chamber to limit the forward and rearward
movement, respectively, of the breechblock, relative to the
casing.
6. A breech mechanism as claimed in claim 5, said means for locking
including a rod attached to the casing and engaging helical
surfaces in the said enlargement of the breechblock.
7. A breech mechanism as claimed in claim 5, including a nut fixing
the said one end of the spring in the fluid-tight chamber, said nut
formed in the said enlargement.
Description
The present invention relates to breech mechanisms for automatic
and semi-automatic guns of the type including a breechblock adapted
to be locked by rotation and which is provided, on the one hand, at
the front part thereof, with a cup-shaped recess in which is
engaged the rear part of a cartridge to be fired, and, on the other
hand, on the outside, with locking lugs which co-operate with lugs
provided in a sleeve rigid with the gun barrel, the breech
mechanism further comprising a casing surrounding the breechblock
and slidable longitudinally without rotation in a breechcase, means
being provided between said casing and the breechblock to transform
into a rotary movement of the breechblock (which is then locked) at
least a portion of the translatory motion that takes place between
the casing and said breechblock once the latter reaches
substantially its front closing position.
The object of the present invention is to provide a breech
mechanism which is better adapted to meet the requirements of
practice than those known at the present time.
According to a first feature of the present invention, in a breech
mechanism of the type indicated above, there are provided on a
common geometrical cylinder of revolution, on the one hand, the
external surface of the breechblock lugs and at least a portion of
the external surface of the casing surrounding the breechblock, and
on the other hand, at least a portion of the internal surface of
the breechcase, whereby the breechblock is guided along this
portion of the internal surface of the breechcase not only by the
casing but also by at least some of the breechblock lugs. For the
sake of convenience, said portion of the internal surface of the
breechcase will be called hereafter "cylindrical portion," it being
understood that this portion does not necessarily form an entire
cylinder, but may form only part or parts of a cylinder.
A second feature of the present invention consists, in a breech
mechanism of the type indicated above, in providing, in the lateral
outer surface of the casing, two diametrically opposed longitudinal
bosses, the lateral longitudinal faces of which co-operate with
guiding faces provided in the breechcase for the purpose of
preventing the casing from rotating inside the breechcase, one of
these bosses having a front face adapted to co-operate with a sear
for stopping the breech mechanism whereas the other of these bosses
has a front face adapted to co-operate with the device for
unlocking the breech mechanism from the breechcase, on the one
hand, and with the resetting device, on the other hand, which last
mentioned boss may possibly co-operate through the rear portion
thereof with an ejector for rocking this ejector.
A third feature of the present invention consists, in a breech
mechanism of the type indicated above, in separating the lugs of
the breechblock from one another by angular spaces one of which
accommodates an extractor carried by the breechblock whereas the
angular space diametrically opposed to the preceding one extends as
far as the inside of the cup-shaped recess to provide a passage for
an ejector carried by the breechcase.
A fourth feature of the present invention consists, in a breech
mechanism of the type indicated above, in providing, on the one
hand, directly between the breechblock and the casing, a blocking
device adapted to work at the end of the unlocking of the breech
mechanism, for imperatively maintaining said casing in the extreme
rear position with respect to the breechblock during the
reciprocating movement of the breech mechanism inside the
breechcase and, on the other hand, on the breechcase, a release
device adapted to act, at the end of the breech mechanism closing
operation, upon the blocking device for making it inoperative.
A fifth feature of the present invention consists, in a breech
mechanism of the type indicated above, in distributing the
breechblock lugs along at least two annular rows the rear active
faces of which are located on two identical but distinct skew
helical lines spaced axially at a distance from each other greater
than the pitch of said helical lines.
The present invention further relates to breech mechanisms for
automatic or semi-automatic guns of the type which comprise, on the
one hand, a breechblock provided, at the front end thereof, with a
cup-shaped recess into which is engaged the rear part of a
cartridge to be fired, said breechblock being adapted to be locked
with respect to an element rigid with the gun barrel, and, on the
other hand, a locking member for controlling (control stroke) and
maintaining (safety stroke) the locking of the breechblock, this
member being mechanically connected with a firing pin movable with
respect to the breechblock and subjected to the action of at least
one firing spring bearing upon the breechblock. This invention is
more especially, but not exclusively, concerned with breech
mechanisms of the type first indicated above, wherein this locking
member is essentially constituted by said casing and is adapted to
rotate the breechblock in one direction (control stroke) so that
the lugs it carries are screwed in front of the lugs carried by the
breechcase, then to perform a safety stroke preventing the
breechblock from rotating in the opposed direction.
A sixth feature of the present invention consists, in a breech
mechanism of this second type (and possibly also of the first type
indicated above), in using a semi-positive connection between the
firing pin and the locking member (casing) such that, when the
locking member has only partly completed the safety stroke, the
firing pin can reach the primer of the cartridge received in the
cup-shaped recess to fire it before the end of the safety
stroke.
Preferred embodiments of the present invention will be hereinafter
described with reference to the appended drawings given merely by
way of example, and in which:
FIG. 1 is a longitudinal sectional view of a breech mechanism made
according to the present invention and of the gun elements that
co-operate with this breech mechanism;
FIG. 2 is a view similar to FIG. 1 showing a breech mechanism made
according to a first modification;
FIG. 3 is a transverse sectional view, in particular on the line
III--III of FIG. 2, of one of the breech mechanisms of FIGS. 1 and
2;
FIG. 4 is a separate view of the breechblock in longitudinal
section analogous to that of FIGS. 1 and 2;
FIG. 5 shows, from the left hand side of FIG. 4, the same
breechblock with, in cross section, the ejector;
FIG. 6 is a view of the breechblock of FIG. 4 seen from above;
FIG. 7 is a longitudinal half-section showing some of the elements
of FIG. 1 in a different working position; and
FIG. 8 shows, similarly to FIG. 3, a breech mechanism made
according to a second modification.
The particular embodiments illustrated by way of example in the
drawings relate to automatic guns of calibre comprised between 20
and 40 mm.
The breech mechanism comprises a breechblock 1 which is locked by
rotation, this breechblock including, on the one hand, at the front
thereof, a cup-shaped recess 2 which engages the rear part of the
cartridges to be fired (not shown) and, on the other hand, at the
periphery thereof, locking lugs 3 adapted to co-operate with
corresponding lugs 4 provided in a sleeve 5 rigid with gun barrel
6. The breech mechanism further includes a casing 7 surrounding
breechblock 1 and slidable longitudinally without rotation in
breechcase 8. Means are provided between the casing 7 and the
breechblock 1 for transforming into a rotary movement of the
breechblock 1 (and to lock said breechblock by the intermediary of
lugs 3 and 4) at least part of the translatory motion which takes
place between the casing 7 and said breechblock 1 when said
breechblock arrives substantially in its front closing position
(position shown in FIGS. 1 and 2).
Breechblock 1 is made of a single piece (see, in particular, FIGS.
4 to 6) of substantially cylindrical shape about axis X--X which
coincides both with the axis of rotation of this breechblock and
with the axis of barrel 6. Said breechblock 1 projects from casing
7, at the rear thereof, through a hole 9, whereby the rear face 10
(FIG. 1) or 10a (FIG. 2) of said breechblock 1 co-operates with the
conventional breech mechanism damping device 11 carried by the rear
portion of breechcase 8.
In the embodiment of FIG. 2, the rear face 10a of breechlock 1
co-operates directly with said damping device 11 (similar to that
diagrammatically shown by FIG. 1). According to the embodiment of
FIG. 1, the rear face 10 of the breechlock 1 constitutes a bearing
face for a plug 12 mounted on said breechlock by means of a bayonet
joint 13, the rear of this plug being interposed between said face
10 and damping device 11.
Whatever be the embodiment that is chosen, breechblock 1 extends
from the rear to the front of the breech mechanism and determines
substantially (that is to say except for the thickness of plug 12)
the length of the breech mechanism, which is thus greatly
reduced.
To facilitate assembly, casing 7 is advantageously made of two
casing elements or shells 7a and 7b adjoining each other along a
diametral plane (plane of FIGS. 1, 2 and 7) and ridgidly
interconnected in the longitudinal direction by radial studs 14
(for instance one stud carried by casing element 7a located between
two studs carried by casing element 7b, as shown by FIGS. 1,2, 3
and 7).
A transverse spindle 15 extends across breechlock 1 in a manner
that will be hereinafter explained. This spindle is connected,
inside breechlock 1, with a firing pin 16 (FIGS. 1 and 7) or 16a
(FIG. 2) to operate it; and spindle 15 is connected, outside this
breechlock 1, without play, to casing 7. Breechlock 1 is provided
with a longitudinal recess 17 which, in the absence of a plug such
as 12, is open towards the rear and receives the body of firing pin
16 and guides it with a translatory movement parallel to axis X--X.
Furthermore, to accommodate firing pin 16 or 16a, breechlock 1 is
provided, at the front thereof, with a passage 17a which opens into
cup-shaped recess 2.
According to the embodiments of FIGS. 1, 2, 3 and 7, spindle 15 has
one end thereof engaged in the element 7a of casing 7 and the other
end thereof in element 7b. According to the modification of FIG. 8,
wherein the elements are designated by the same reference numbers
as in the other figures, but increased by 100, spindle 115,
connected to firing pin 116, is located in the plane of assembly of
elements 107a and 107b and is therefore engaged, at each end
thereof, half in element 107a and half in element 107b.
According to a first feature of the invention, the outer surface of
the lugs 3 of breechblock 1 is located in the same geometrical
cylinder of revolution C (FIGS. 1, 2 and 5) as at least a portion
of the outer surface of casing 7. The diameter D of this cylinder
is equal to the inner diameter of a cylindrical portion 18 of
breechcase 8, along which cylindrical portion 18 move lugs 3 and
casing 7. It is pointed out that lugs 3, as visible in FIGS. 1 and
2, are not located in the plane of these figures (see FIG. 5),
which explains why their lower outline does not coincide with the
intersection of cylinder C and said plane.
Thus, during its reciprocating movement, breechblock 1 is guided
along cylindrical portion 18 not only by contact with casing 7 (in
the manner which will be hereinafter described) which is itself in
contact with said portion 18, but also by direct contact of at
least some of its lugs 3 with this portion 18.
In order to transform the translatory movement of breechblock 1
with respect to casing 7 into a rotary movement of said breechblock
about the axis of the gun barrel when the breechblock reaches
substantially its front closing position, illustrated by FIGS. 1
and 2, spindle 15 carries two cylindrical rollers 19 (FIG. 3)
adapted to co-operate with partly helical surfaces 20 (see also
FIG. 4) provided in a cylindrical enlarged portion 21 of
breechblock 1, at least one of the end faces 21a and 21b of this
cylindrical enlarged portion 21 limiting the longitudinal movements
between casing 7 and breechblock 1. As shown by FIG. 4, each of
said surfaces 20 comprises a helical rear portion of a length equal
to a, which corresponds to the locking stroke of casing 7, and a
rectilinear front portion parallel to axis X--X, of a length equal
to b, which corresponds to the safety stroke of casing 7.
Cylindrical enlarged portion 21 has an external diameter equal to
the inner diameter of the recess 22 provided in casing 7 to
accommodate said portion 21. On either side of cylindrical enlarged
portion 21, breechblock 1 includes two cylindrical surfaces 23 and
24 on which elements 7a and 7b fit in a relatively fluidtight
manner so as to form between them said recess 22 the length of
which is sufficient to permit displacement of casing 7 with respect
to cylindrical portion 21, elements 7a and 7b fitting together in a
relatively fluidtight manner along their diametral plane of
separation (plane of FIGS. 1 and 2).
For this purpose, elements 7a and 7b are provided with two inward
annular projections 25 and 26 which limit recess 22 between them
and the inner diameters of which are equal (with the approximation
corresponding to clearance) respectively to the diameters of
cylindrical surfaces 23 and 24 against which these projections are
applied. Rear projection 26 has a front face 26a (forming the rear
wall of recess 22) which, as shown by FIGS. 1 and 2, constitutes an
abutment for the rear end face 21b of enlarged portion 21. Front
projection 25 has a rear face 25a (forming the front wall of recess
22) which, as shown by FIG. 7, constitutes an abutment for the
front end face 21a of enlarged portion 21. The movement of casing 7
toward the front may further be limited by contact of the front
face 25b of the projection 25 of said casing 7 with a shoulder 27
provided on breechblock 1 (FIGS. 1 and 2). Likewise, the movement
of casing 7 toward the rear may further be limited by contact of
the rear face 26b of projection 26 either with the front face of
plug 12 (FIG. 7) or with projections 39 (FIG. 2) provided at the
rear end of breechblock 1. It should be noted that radial studs 14
are provided at the level of rear projection 26.
Thus, recess 22 is made practically fluidtight, the openings
defined by surfaces 20 being closed by casing 7 whatever be the
relative axial position thereof with respect to breechblock 1.
Owing to this fluidtightness, there is obtained a protection of the
locking and unlocking mechanisms of the breechblock against the
penetration of dust, sand, powder combustion residues and the
like.
According to the modification of FIG. 8, the means for giving
breechblock 1 its rotary locking movement consist of two aligned
radial trunnions 28 carried by breechblock 101. Said trunnions 28
carry respective cylindrical rollers 119 engages in partly helical
surfaces 120 provided in casing 107. As shown by this FIG. 8,
trunnions 28 extend along a line at right angles to spindle 115.
Reference character A indicates the amplitude of the angular
displacement of breechblock 101 which produces its locking or its
unlocking. Like surfaces 20 (FIG. 4), surfaces 120 include, in
addition to a helical portion, a rectilinear safety portion.
According to a second feature, the lateral outer surface of casing
7 forms two diametrically opposed longitudinal projections 29 and
30, the longitudinal faces 29a and 30a of case 8, so as to prevent
casing 7 from turning inside said breechcase. Projection 29 is
provided with a front face 29b adapted to co-operate with a sear 32
(FIG. 1) to stop the breech mechanism in the open position whereas
projection 30 is provided with a front face 30b adapted to
co-operate with a device 33 (such as a push-piece actuated by a
gas-tap in the gun barrel) provided for releasing the breechblock
with respect to breechcase 8 (FIG. 1), on the one hand, and with
resetting device 34 (FIG. 2) which permits of resetting breechblock
1 before the beginning of the firing, on the other hand. Projection
30 may still, according for instance to the embodiment of FIG. 2,
co-operate at the rear with an ejector 35 (FIG. 5) for rocking it.
A suitable ejector of this type is shown in greater detail in my
copending application, Ser. No. 810,863, filed Oct. 2, 1968, now
U.S. Pat. No. 3,561,148 issued on Feb. 9, 1971, which is a division
of my previous application Ser. No. 717,524, filed Apr. 1, 1968,
now U.S. Pat. No. 3,447,418, issued June 3, 1969. On the contrary,
according to the embodiment of FIG. 1, it is the lower portion 38a
of plug 12 that is arranged to rock ejector 35. Anyway, projection
30 is provided with a longitudinal 30c for the passage of a part of
the ejector.
Preferably advantage is taken of the increased thickness
corresponding to projections 29 and 30 to provide therein the
radial studs 14, which, as stated above, extend inwardly as far as
projection 26.
Concerning plug 12 (FIG. 1), it advantageously comprises guiding
means which co-operate with breechcase 8 both to hold the plug
radially and to prevent it from rotating, this plug forming a
support on the one hand, toward the rear, for a counter-recoil
spring 36, and on the other hand, toward the front, for a firing
pin spring 37 housed in the recess 17 of the plug 12 at the rear of
firing pin 16. Counter-recoil spring 36 bears, at the front, either
against breechblock 1 (FIG. 1), or against casing 7 (FIG. 2). The
guiding means in question may consist of projections 38 which are
integral with plug 12 and which have a profile analogous to that of
casing 7 with its projections 29 and 30, which enables it to
co-operate on the one hand with cylindrical portion 18 (FIG. 3) for
radial guiding and on the other hand with guiding faces 31 for
maintaining a fixed angular position. The lower portion 38a of plug
12, which actuates the ejector, is then carried by the lower
projection 38. Of course, bayonet joint 12 must be adapted to
enable breechblock 1 to rotate with respect to plug 12 when said
breechblock is locked or unlocked by rotation.
The breechblock is thus guided not only, as explained above, by at
least some of its lugs 3 and casing 7, but also by plug 12. Due to
the fact that said plug has a fixed angular position,
counter-recoil spring 36 does not interfere with its operation.
In the embodiment of FIG. 2, plug 12 is replaced by a plug 12a
which is nearly wholly housed in the recess 17 of breechblock 1,
without the possibility of being acted upon by counter-recoil
spring 36, which can then bear against breechblock 1, or
preferably, as shown, against the rear of casing 7. Plug 12a, which
acts as rear support for firing pin spring 37, is provided with a
longitudinal slot 40 so that it is possible to deform it
resiliently by urging toward each other the projections 41 provided
at the rear thereof, for introduction into recess 17. Then said
projections 41 are allowed to move away from each other so as to
engage into notches provided on the inside of breechblock 1 (as
shown by FIG. 2).
According to a third feature, the lugs 3 of the breechblock 1 are
separated from one another by angular spaces c, d one of which
accommodates an extractor 42 (FIGS. 1 and 2) carried by breechblock
1 whereas the angular space diametrically opposed to the preceding
one extends as far as the inside of the cup-shaped recess 2 to
provide a passage 43 (FIGS. 1, 2 and 4) for ejector 35 which is
carried by the breechcase 8. In the embodiment shown by the
drawings, an angular space of 360.degree./(2n+1) is provided
between the lugs 3 of the breechblock 1, where 2n is the number of
lugs 3 (n being an integer). All the lugs 3 have the same
peripheral development, so that, between two particular adjacent
lugs 3 there is left an angular space c (FIG. 5) greater than the
angular space d extending between the other adjacent lugs taken two
by two. This large angular space c accommodates extractor 42,
whereas the small angular space d that is located opposite to said
large angular space c forms part of passage 43.
Extractor 42 is housed in a slot 44 (FIG. 4) provided between two
lugs 3 and it is kept toward the front and radially toward the
outside by a heel 42a carried by said extractor and engaged in a
recess 45 of breechblock 1 so as to form a bearing and pivoting
abutment as shown in FIGS. 1 and 2. This extractor is kept in
position longitudinally toward the rear by a leaf-spring 46 which
tends to make it penetrate into cup-shaped recess 2. Leaf-spring 46
is fitted at the rear into the cylindrical enlarged portion 21 of
breechblock 1, said spring 46 being itself held longitudinally by
an expansible ring 47. Breechblock 1 is provided with a passage 48
(FIGS. 4 and 6) whose width is equal to that of spring 46. Passage
48 extends rearwardly from recess 45 to the inside of enlarged
portion 21, overhanging edges 49 being provided in said enlarged
portion to hold spring 46 therein. Passage 48 is provided at the
rear thereof with a cylindrical housing 50 whose axis is radial,
and which is adapted to accommodate expansible ring 47. The latter
is of a height such that it is kept in position by casing 7 as
shown by FIGS. 1, 2 and 3.
According to the embodiment illustrated (see in particular FIG. 5),
n is equal to 3 so that breechblock 1 is provided with six lugs 3
spaced apart by 360.degree./7, with the exception of the two upper
lugs which are at 720.degree./7 from each other. These angular
spacings are measured from the middle axis of one lug to the middle
axis of the next lug, and thus do not take into account the
circumferential width of the lugs.
According to a modification (not illustrated), an angular space of
180.degree./(n+1) is provided between the lugs of the breechblock
distributed in two symmetrical groups, where 2n is again the number
of lugs which have substantially the same peripheral development.
There are two diametrically opposed large angular spaces of
360.degree./(n+1) one of which accommodates extractor 42 whereas
the other provides passage 43.
According to a fourth feature there is provided, on the one hand,
directly between breechlock 1 and casing 7, a blocking device
adapted to come into play at the end of the unlocking of the breech
mechanism, to hold casing 7 imperatively in its extreme rear
position with respect to breechlock 1 (position illustrated by FIG.
7), during the reciprocating movement of the breech mechanism in
breechcase 8 and, on the other hand, on said breechcase, a release
device located to act, at the end of the breech mechanism closing
movement, upon the blocking device to put it out of action.
Preferably, said blocking device comprises a strip 51 (FIGS. 1 and
7) carried by breechblock 1 and the rear end of this strip is
resiliently urged (preferable by the elasticity of the strip
itself) radially away from the external surface of breechblock,
that is to say into the path of the front face 26a of projection
26. The release device includes a piece provided with an inclined
face 52 carried by breechcase 8, a push-piece 53 housed in casing 7
being interposed between said inclined face 52 and strip 51.
Advantageously (as shown), said strip 51 has its front end tightly
held in the rear part of enlarged portion 21, which is provided for
this purpose with a passage 52 (FIG. 4) limited at the front by
projections 54a serving to wedge strip 51.
It should be noted that, in order to simplify the drawings, it has
been supposed in FIGS. 1, 2 and 3 that extractor 42, passage 43,
spring 46 and strip 51 are located in the plane of assembly of
shells 7a and 7b. In reality, this condition is complied with only
when (contrary to the case of FIGS. 1, 2 and 3) casing 7 is located
in its extreme rear position with respect to breechblock 1, as
shown by FIG. 7 where strip 51 is shown correctly in said plane of
assembly, due to the rotation of breechblock 1 with respect to
casing 7 as permitted by the recoil movement of the latter.
According to a fifth feature, the lugs 3 of the breechblock 1 are
distributed in two annular rows the active rear faces f of which
are located along two skew helical surfaces H.sub.1 and H.sub.2
(FIG. 6) identical to each other but distinct, and which are spaced
apart in the axial direction by a distance l from each other
greater then the common pitch p of said helical surfaces. Reference
characters 3a and 3b designate respectively the two rows of lugs 3.
The advantage of this construction consists in the lengthening of
at least some of said lugs 3 in the axial direction. This is due to
the fact that, if the faces f of all the lugs 3 were located in the
same helical surface, as usual, their axial length could be at most
equal to the differences between the pitch p and the axial length
of the lugs 4 of sleeve 5 which must pass between the lugs 3a and
3b of the two successive rows.
Furthermore, each beginning 56 and each end 57 of the rows of lugs
3a and 3b advantageously line the large angular space c (FIG. 5)
provided for extractor 42 (FIGS. 1 and 2), which facilitates the
machining of lugs 3 which would tend to be rather delicate in view
of the offsetting of helical surfaces H.sub.1 and H.sub.2.
According to a first solution, the helical surfaces H.sub.1 and
H.sub.2 and also the helical surface H.sub.3 in which are located
the front faces q of the rear lugs 3b, have inclinations such that
reversibility of the movement is prevented. The term "inclination"
designates the angle between two planes passing through any
perpendicular to the axis X--X of the helical surfaces, namely a
plane tangent to this helical surface and a plane perpendicular to
said axis. "Reversibility" means that a thrust exerted from left to
right on breechblock 1, from the position shown by FIGS. 1 and 2,
is capable of rotating said breechblock despite friction
phenomenons. In order to prevent reversibility the angle in
question may be given a value of about 5.degree. or less.
According to a second solution, helical surfaces H.sub.1, H.sub.2
and H.sub.3 have inclinations such that reversibility of the
movement is permitted, the angle defined above being then generally
at least equal to 6.degree. or 7.degree..
The lugs 3 of the breechblock 1 may also be distributed in at least
one row whose rear face f would be located in a plane perpendicular
to the axis of the breechblock.
According to the preceding description, the gun comprises locking
means (casing 7) for controlling (control stroke a, FIG. 4) and
maintaining (safety stroke b) the locking of breechblock 1 with
respect to an element (sleeve 5) rigid with the gun barrel 6, this
means being mechanically connected with firing pin 16a movable with
respect to breechblock 1 and subjected to the action of at least
one firing pin spring 37 bearing upon the breechblock.
According to a sixth feature, which is preferably applied to the
locking means described above but which may be applied to locking
means of a different type (for instance adapted to operate locking
members carried by a non-rotary breechblock), a semi-positive
connection is used between the firing pin 16a and the locking
means, such that, while the locking means (casing 7) have moved
only a portion of the safety stroke, firing pin 16a can reach the
primer of the cartridge (that is to say project into cup-shaped
recess 2) and fire it before the end of said safety stroke.
According to the embodiment of FIG. 2 it suffices for this purpose
to provide firing pin 16a with a slot 55 elongated in the direction
of the axis X--X, extending through firing pin 16a. Preferably,
firing pin 16a is given a weight such that it opposes rebounding of
the locking means or casing 7. This feature will be better
understood by comparing the structure of FIG. 2 with that of FIG. 1
where spindle 15 extends through firing pin 16 through a hole
leaving no longitudinal play and where the firing pin is of smaller
volume and therefore less heavy.
Owing to the anticipated firing thus achieved, a higher rate of
firing and an improved safety of operation are obtained.
The breech mechanism described above works as follows: Before
firing, casing 7 is held in a rear position by sear 32 (FIG. 1)
which co-operates with its face 29b. Breechblock 1 is also held in
a rear position. Casing 7 is further held in its rear position with
respect to breechblock 1 (as shown by FIG. 7) by the fact that
strip 51, fixed to said breechblock, bears upon the face 26a of the
casing. Firing pin 16 or 16a is also kept in its rear position,
against the action of spring 37, with respect to breechblock 1 by
spindle 15 rigid with casing 7.
By acting upon sear 32, the gunner releases the whole of the breech
mechanism with casing 7. The whole breech mechanism is thrust in
the frontward direction by counter-recoil spring 36 and receives in
cup-shaped recess 2 a cartridge which is introduced into barrel 6.
Once push-piece 53 comes to the level of inclined face 52, strip 51
is retracted into the position of FIGS. 1 and 2 and releases casing
7 with respect to breechblock 1. When said breechblock has reached
approximately its closing position, shown by FIGS. 1 and 2, its
lugs 3 come ahead of the lugs 4 of sleeve 5, which permits rotation
of the breechblock. Firing pin spring 37, acting through firing pin
16 or 16a and spindle 15, drives toward the front casing 7 which is
guided in such manner that it can have no movement of rotation
about itself. It follows that spindle 15, which carries rollers 19,
first assumes a movement corresponding to the helical portion a of
inclined surface 20 (FIG. 4), thus rotating breechblock 1 and
screwing the lugs 3 thereof in front of the lugs 4 of sleeve 5.
Then spindle 15, moving along the rectilinear portion b (safety
stroke) of surface 20, prevents a reversing of the rotation which
would release the breechblock. At the same time, firing pin 16 or
16a is driven frontwardly and enters recess 2, thus firing the
primer of the cartridge present in the barrel.
According to the embodiment of FIG. 2 the longitudinal play
permitted by slot 55 enables firing pin 16a to strike the primer
before the end of the safety stroke b (advanced firing), then to
come into contact with breechblock 1 which limits the forward
movement of said firing pin. As the time of firing of the cartridge
is of the order of 2/1,000 of a second, casing 7 and spindle 15
keep moving forward up to the position (end of stroke) shown by
FIG. 2 and, in case said casing and spindle 15 rebound (for
instance when the time of firing exceeds 2/1,000 of a second), they
meet during their rearward movement, resulting from rebounding, the
rear end of the slot 55 of firing pin 16a which, due to its weight,
will stop their movement.
After the cartridge has been fired, the gases developed in barrel 6
(or any other equivalent device) cause push-piece 33 to move
rearwardly, breechblock 1 remaining stopped by its lugs 3. Spindle
15, which carries rollers 19, after having moved through safety
stroke b, reaches helical path a and causes breechblock 1 to rotate
in the unlocking direction. At the end of the unlocking stroke, the
elements come back into their relative mutual positions of FIG. 7
where they are maintained by strip 51. According as the gunner
continues or not to act on sear 32, the breech mechanism is either
driven again in the frontward direction or retained by said
sear.
In view of the inclination of the faces f and g of the lugs 3 of
breechblock 1 and of the corresponding faces of the lugs 4 of
sleeve 5 (with or without reversibility), a longitudinal relative
movement takes place during the locking and unlocking strokes.
This leads to the following advantages.
On the one hand, during locking, breechblock 1 can be in rotation
(due to the relative longitudinal displacement of the casing caused
by the firing pin spring and the counter-recoil spring 36) before
it comes into abutment at the end of the frontward stroke (about
1.5 mm), and on the other hand, during unlocking, breechblock 1,
which drives the extractor in its relative rearward movement,
permits of detaching the cartridge case to be extracted from the
cartridge chamber when the residual pressure in the gun barrel is
still relatively high and before the casing reaches the end of its
unlocking stroke toward the rear.
In the case of reversibility, there is further obtained a self
unlocking of the breech mechanism, after the controlled recoil of
casing 7 in the safety stroke b (FIG. 4) owing to the thrust
transmitted by the case of the cartridge that has just been fired,
which could, for example, permit the rate of fire to be
increased.
While the above description discloses preferred embodiments of the
invention, it should be understood that said invention is not
limited thereto, as there might be changes made in the arrangement,
disposition and form of the parts without departing from the spirit
or scope of the invention.
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