US3058398A

US3058398A - Automatic machine gun with recoiling barrel and hydraulic accelerator

Info

Publication number: US3058398A
Application number: US861714A
Authority: US
Inventors: Irwin R Barr
Original assignee: Aircraft Armaments Inc
Current assignee: Textron Systems Corp
Priority date: 1959-12-23
Filing date: 1959-12-23
Publication date: 1962-10-16
Anticipated expiration: 1979-10-16

Description

2 Sheets-Sheet 1 Filed Dec. 25, 1959 INVENTOR.

[PW/IV A? BABE BY z a United States Patent 8 Claims. (Cl. 89-169) This invention relates in general to firearms and more particularly to an automatic machine gun having a variable rate of fire.

An object of this invention is to provide an automatic machine gun having a hydraulic accelerator for actuating the breechblock and allowing the firing rate of the gun to be controllably varied over a wide range.

Another object of this invention is to provide a machine gun of simple and rugged construction and which is dependable in operation.

Still another object of this invention is to provide a machine gun which is smoother in operation than machine guns of conventional construction.

Further and other objects will become apparent from a reading of the following detailed description taken in conjunction with the accompanying drawing wherein like numbers refer to like parts.

In the drawing:

FIGURE 1 is a fragmentary sectional side view of the machine gun of this invention.

FIGURE 2 is a section taken on line 22 of FIG- URE 1.

FIGURE 3 is a section taken on line 3-3 of FIG URE 1.

The machine gun as shown in FIGURE 1 includes a housing 2 having a generally cylindrically shaped opening 3 formed at its forward end for receiving a gun barrel 4. Suitable bearing means 5 are provided in cylindrical opening 3 for supporting barrel 4 and allowing only axial movement thereof relative to the housing. A barrel extension 6 forming a breech is rigidly connected to the inner end 7 of barrel 4 so as to represent an integral part thereof. As best shown in FIGURE 3 barrel extension 6 is supported within housing 2 by projections 8 formed on the inner wall of the housing so that it may move freely with the barrel.

A breechblock 9 slidably carried by barrel extension 6 provides the means for loading, firing and unloading the gun in response to axial recoil movement of the barrel.

Breechblock 9 includes a base member or bolt slide and a movable member or bolt block 26 slideably carried by the base member. A pair of door-like locking members or cam means 27 and 28 are swingably carried by movable member 26 through

pins

29 and 30. Pins 31 and 32 provided on members 27 and 28 engage cam-like slots 33 and 34 formed on base member 25. The shape of slots 33 and 34 and such that when movable member 26 is moved rearwardly relative to the base member, the door-like locking members 27 and 28 are caused to move outwardly and engage

notches

35 and 36 formed in barrel extension 6 and thereby lock the breechblock relative to the barrel extension. Thus, locking members 27 and 28 are similar to latches, and

notches

35 and 36 are similar to keepers. An accelerator rod 18, generally co-axially aligned with barrel 4, is fixedly secured to base member 25 of breechblock 9 by means of pin 19. The forward end of rod 18 is formed as a firing pin 37 which is adapted to project through an opening 38 in movable member 26. The forward end of movable member 26 is formed with a T-slot 39 for supportingly engaging the head of an ammunition round as best shown in FIGURE 2. The length 3,058,398 Patented Oct. 16, 1962 of rod 18 is such that firing pin 37 at the forward end thereof engages the head of bullet 40 and thereby causes it to fire when movable member 26 is moved rearwardly relative to base member 25 for locking the breechblock. This action occurs by pushing the base member 25 forwardly after the movable member 26 butts against the forward end of barrel extension 6.

A fluid-filled hydraulic cylinder 10 formed rigid with housing 2 is adapted to slidably receive a driving piston 11 adjacent its forward open end 12. In the opposite end of hydraulic cylinder 10 a shock absorbing bufier piston 13 is arranged to move axially of the housing against the action of a spring 14. As shown in FIGURE 1 the pressure exerted by spring 14 against buffer piston 13 may be varied by the adjusting plug 15.

A piston chamber 16 formed as a part of housing 2 and generally co-axially aligned with barrel 4 is provided with an opening 17 at its forward end for receiving ac" celerator rod 18. A driven piston 20 slidably carried within chamber 16 is provided with an axial bore arranged to slidably receive the rearward end 21 of rod 18 extending within the chamber. A head 22 formed on the extreme rearward end 21 of rod 18 projecting beyond piston 20 butts thereagainst to limit the relative movement between the piston and the rod so that as piston 20 is caused to move rearwardly the breechblock is caused to move with it. A port 23 connects cylinder 10 with chamber 16 so that fluid within chamber 10, when pressurized through the action of driving piston 11, will exert a force on driven piston 20 in chamber 16. A radial cut-out 24 in the outer periphery of the driven piston at the forward end thereof allows the fluid pressure to exert a force urging the piston rearwardly within chamber 16 even when the piston is in the extreme forward position butting against the forward wall of chamber 16.

A breechblock buffer cylinder 41 is arranged rearwardly of chamber 16 and forms a part of housing 2. A buflfer piston 42, slidably received within cylinder 41, is urged in an extreme forward position, a shown in FIGURES l and 2, by means of a spring 43 acting between piston 42 and an adjusting plug 44. An aperture 45 formed in pis ton 42 and in the rearward end of chamber 16 permits rod 18 carried by the breechblock to extend into buffer cylinder 41 as required to allow the necessary movement of the breechblock for the loading and unloading opera tions of the gun. A breechblock return spring 46 acting between piston 42 and base member 25 of the breech block urges the latter into the forwardmost locked position shown in FIGURES 1 and 2. A guide pin 47 secured to piston 42 and extending into an opening 48 formed in breechblock 9 provides a suitable guide for spring 46.

A normally projecting extension 49 on barrel extension 6 carries a hammer 50 threadedly engaging extension 49 and co-axially aligned with opening 12 in the forward end of chamber 10. Thus as barrel 4 is moved rearwardly hammer 50 is caused to engage driving piston 11 in chamber 10 and compress the fluid stored therein whereby to exert a force on driven piston 20 for causing it to unlock and accelerate breechblock 9 rearwardly relative to the barrel and barrel extension. Hammer 50 is spaced a predetermined distance from piston 11 to permit barrel 4 and breechblock 9 to move rearwardly together a short distance while the gasses within the barrel produced by firing a round of ammunition are allowed to subside so as to avoid blowback and to permit unlocking of the breech block. By varying the distance of hammer 50 from piston 11, the firing rate of the gun may be varied since this adjustment controls the amount of energy which will be imparted to driving piston 11.

Additional control over the firing rate of the gun may be provided as shown in FIGURE 1 wherein piston 51 carried by extension 49 is arranged'to engage a spring 52 within a housing 53 so that the rearward movement of the barrel and its extension may be opposed by the spring for absorbing a part of the energy of the moving barrel. Adjusting means 54 may be provided for varying the amount of force exerted on piston 51 by spring 52.

Suitable means for urging barrel 4 into its forwardmost position is shown in FIGURE 2 wherein a pair of pistons 55 and 56 carried by barrel extension 6 engage springs 57 and 58 carried by housing 2.

Trigger means for controlling the operation of the gun is shown in FIGURE 1 wherein a latch 59 is pivotally carried by a piston 60 slidably supported for limited axial movement within bracket 61. A spring 62 within bracket 61 contacts piston 60 for absorbing shock loads applied to latch 59. A spring urged plunger 63 is carried by latch 59 so as to engage the wall of housing 2 and urge the latch into a downward position for engaging a notch 64 formed in breechblock 9. When the breechblock is moved to its rearwardmost position, so as to be engaged by latch 59, it is prevented from moving forward until the latch is disengaged. An actuating lever 65 pivotally carried by housing 2 through pin 66 engages a projection 67 on latch 59 so that by rotating lever 65 the breechblock may be unlocked and the gun allowed to operate.

A door 68 forming a part of housing 2 is hinged at 69 to provide access to the breechblock and other gun mechanism. Lock means 70.is provided for releasably securing door 68 in its closed position shown in FIGURE 1.

As best shown in FIGURE 3, openings 71 are provided on either side of housing 2 through which ammunition rounds may be fed to the gun. An opening 72, provided in the under side of barrel extension 6 and housing 2 provide a path for ejecting the empty cartridges from the gun breech after firing.

The details of the gun mechanism for feeding the ammunition into the gun breech and for ejecting the shells is not shown since this mechanism does not form a part of this invention. Any conventional arrangement for performing this function may be employed. As shown in FIGURE 1, a lever 73 is pivotally carried by door 68 through pin 74 so that one end thereof will engage a groove 75 formed in the upper surface of breechblock 9 as best shown in FIGURE 3. Groove 75 serves as a cam whereby movement of the breechblock will produce controlled rotation of lever 73. The free end of lever 73 is provided with a pawl arrangement (not shown) for engaging a round of ammunition so as to pull it into position forwardly of the breechblock so that the head of the cartridge will engage T-slot 39 and thereby enable the breechblock to push it into firing position as shown in FIGURES 1 and 2.

The operation of the gun can best be described by assuming that the firing cycle begins with breechblock 9 being held in its rearwardmost loading position by latch 59 of the trigger mechanism. At that time an ammunition cartridge is positioned between the breechblock and the barrel in line with T-slot 39. As the trigger is pulled, rotating lever 65, latch 59 is caused to pivot so as to release the breechblock whereby return spring 46 forces the breechblock forwardly to the position shown in FIGURES 1 and 2. As the breechblock is moved forwardly, the loading mechanism (not shown) forces the round into coaxial alignment with barrel 4 and into engagement with T-slot 39 whereby when the breechblock reaches the forwardmost position shell 40 is secured within barrel 4. Further forward movement of breechblock base member 25 relative to movable member 26, which occurs after movable member 26 engages the forward wall of barrel extension 6, causes firing pin 37 to project through aper ture 38 and engage the head of shell 40 causing it to fire. The forward movement of base member 25 relative to movable member 26 also causes door-like locks 27 and 28 to swing outwardly so as to engage

notches

35 and 36 formed in barrel extension 6 and lock the breechblock into the forward most position for transmitting the reaction forces produced by firing the round to the barrel and barrel extension. Thus as the shell is fired, the reaction forces cause the barrel and its extension to move rearwardly against the action of barrel return springs 57 and 58. Breechblock 9 remains locked to the barrel extension 6 for a short distance of rearward recoil movement of the barrel to permit the gases produced by firing to subside. After the barrel is moved rearwardly a short distance, hammer 50 carried by extension 49 engages driving piston 11 and compresses the fluid within chamber 10. Rearward movement of barrel 4 is limited by extension 49 engaging the forward end 12 of the cylinder. The shockload applied to driving piston 11 is cushioned by bulfer piston 13 in cooperation with spring 14. The pressurized fluid reacts against driven piston 20 causing it to be driven rearwardly within its chamber 16. As piston 20 is driven rearwardly, rod 18 is also pulled rearwardly relative to member 26 causing door-like locks 27 and 28 to be swung inwardly as guided by cams 33 and 34 and unlock breechblock 9 from the barrel extension. Further movement of piston 20 causes the breechblock to be accelerated rearwardly with considerable force whereby the breechblock engages buffer piston 42 whence it is decelerated and started on its forward stroke. As the breechblock is moved rearwardly the loading mechanism, actuated by lever 73, positions a second round of ammunition ahead of the breechblock and in line with T-slot 39. While the breechblock is still moving rearwardly, the barrel and barrel extension is returned to the most forward position by the action of springs 57 and 58. The forward motion of breechblock 9, as effected by return spring 46, *actuates suitable mechanism (not shown) for ejecting the empty shell and for replacing it with the second round of ammunition in coaxial alignment with barrel 4. As the breechblock continues to move forwardly, the new round is pushed into firing position, the breechblock is locked relative to barrel extension 6, the firing pin moves forwardly relative to breechblock movable member 26 and is fired. The firing of the second round causes the barrel and its extension member to move rearwardly as previously described to actuate the breechblock accelerator and pull another round of ammunition into the gun to start another firing cycle. The gun will continue to fire in this manner so long as trigger member 65 is pulled to prevent latch 59 from engaging notch 64 on the breechblock. By releasing member 65, latch 59 is allowed to engage the breechblock notch and prevent continued operation.

It should be noted that the pin-and-

slot connection

31, 32, 33, 34 between

members

25 and 26 serves to couple the latter in a particular manner. When member 26 abuts the barrel adjacent the chamber, and spring 46 moves member 25 forwardly relative to member 26, the pin-andslot connection causes locking members 27, 28 to pivot outwardly into

notches

35, 36 as the firing pin 37 slides in opening 38 in member 26 to fire cartridge 40. When the hydraulic accelerator causes member 25 to move rearwardly relative to member 26 during recoil movement of the barrel, the pin-and-slot connection causes locking members 27, 28 to pivot inwardly out of

notches

35, 36. When member 25 moves further rearwardly relative to the chamber, the pin-and-slot connection couples member 26 to member 25 and causes such further rearward movement to slide member 26 to its unloading position. When return spring 46 moves member 25 forwardly on its counter-recoil stroke, a side of the barrel extension upon which the breechblock is slideably mounted prevents the locking members from rotating to their outward positions so that the pin-and-slot connection couples member 26 to member 25 and causes the former to move forwardly er time.

the change in stroke of piston 11. Additional control over the firing rate may be had by regulating the force exerted by spring 52 as shown in FIGURE 1 whereby to oppose the recoil movement of barrel 4.

The use of the buffer piston 13 for absorbing shock loads and preventing the occurrence of sudden pressure changes in the fluid also functions to accelerate the breechblock after the barrel and barrel extension have completed their rearward movement because of the energy stored in the buffer piston spring 14. This is most desirable since it allows the force applied to accelerate the breechblock to be continued over a longer period of time than with accelerators of conventional construction whereby peak loads may be less and still impart the same amount of energy to the breechblock as would be imparted by a larger accelerating force applied over a short- Therefore, the breechblock and its associated structure will not be stressed as heavily as those parts in conventional machine gun construction whereby the parts may be made less rugged and consequently lighter in weight. A further important operational advantage is obtained by reducing the peak accelerating loads, in that the gun will operate more smoothly.

Though the machine gun has been shown and described in considerable detail, it is to be understood that certain alterations, modifications and substitutions may be made without departing from the spirit and scope of the invention as defined by the appended claims.

As used in this application, the barrel is considered to be in battery" when it is fully returned from recoil, and the barrel is considered to be out of battery when it is not fully returned from recoil. The words recoil movement are used to mean the backward movement of the barrel or part thereof on firing caused by the backward pressure of the propellent gases, and the distance that the barrel or part thereof travels in this backward movement. The words counterrecoil movement are used to mean the forward movement of the barrel or part thereof returning to firing position (battery) after recoil.

This application is a substitution application for Serial No. 354,975, filed May 14, 1953, now abandoned.

What is claimed is:

1. An automatic machine gun comprising a housing, a chambered gun barrel mounted in said housing for recoil movement from a forward in-battery position to a rearward recoil position, a barrel extension attached to the rear portion of said barrel adjacent the chamber, a movable member slideably mounted on said barrel extension and having a firing position adjacent the rear portion of the barrel and a recoil position remote from said rear portion, a locking member pivotally mounted on said movable member, a base member slideably mounted on said barrel extension rearward of said movable member, connection means between said base member and said locking member, said base member having a firing pin rigid therewith for contacting a cartridge in the chamber to fire the same when the base member is at a foremost position relative to the barrel extension, a driving spring for moving said base member to said foremost position, means for causing said connection means to couple said 'movable member to said base member when said driving spring moves said base member toward said foremost position until said movable member is at firing position, movement of said base member to said foremost position causing said connection means to move said locking mem ber into locking engagement with said barrel extension for attaching said movable member to said barrel extension as said firing pin contacts and fires the cartridge in the chamber, firing of the cartridge causing an initial recoil movement of the barrel and barrel extension toward recoil position with said movable member locked to said barrel extension, movement on said barrel extension of said base member rearward of its foremost position first causing said connection means to move said locking member out of engagement with said barrel extension for detaching said movable member from said barrel extension and then causing said connection means to couple said movable member to said base member for moving said movable member to its recoil position, an hydraulic cylinder containing fluid, a driving piston for pressurizing said fluid upon actuation thereof, a driven piston connected to said base member, said driven piston being responsive to pressurization of said fluid for moving said base member rearward of its foremost position, and hammer means on said barrel extension engageable with said driving piston during recoil movement of the barrel toward recoil position for actuating said driving piston.

2. An automatic machine gun in accordance with claim 1 wherein said hammer means is spaced from said driving piston when the barrel is at battery position so that the driving piston is actuated after limited recoil movement of the barrel whereby said base member is moved rearward of its foremost position after such limited recoil movement of the barrel.

3. An automatic machine gun in accordance with claim 1 including: a buffer piston, and spring means resiliently urging said buffer piston in one direction, said buffer piston being responsive to pressurization of said fluid for moving said buffer piston in the opposite direction to compress said spring means whereby said spring means absorbs shock loads applied to said driving piston and assists movement of said base member rearward of its foremost position.

4. An automatic machine gun comprising, a housing, a barrel extension, a barrel attached to said barrel extension, said barrel extension and barrel being slideably mounted in said housing for recoil movement as a unit from a battery to a recoil position, said barrel having a chamber adjacent one end of the barrel extension for holding a cartridge, a base member slideably mounted on said barrel extension for reciprocation thereon between terminal positions, said base member having a firing pin rigidly attached thereto, reciprocation of said base member to one terminal position adjacent said one end of the barrel extension causing said firing pin to contact and fire a cartridge in the chamber, a movable member mounted for reciprocatory movement on said barrel extension between operative and inoperative positions, the operative position of said movable member being adjacent said one end of the barrel extension for engaging the base of the cartridge to retain the same in the chamber, the inoperative position of said movable member being remote from said one end of the barrel extension for etfecting removal of a cartridge from the chamber, a locking member movably mounted on said movable member, notch means on said barrel extension adjacent said one end, said locking member being engageable with said notch means when the movable member is in operative position, said locking member when engaged with said notch means being effective to cause the movable member to retain the cartridge in the chamber against the pressure of the propellent gases generated when the cartridge is fired, connection means interconnecting said base member with said movable member so that reciprocation of said base member to said one terminal position simultaneously causes movement of said movable-member to its operative position and engagement of said locking member with said notch means as the firing pin contacts and fires the cartridge in the chamber whereby the barrel extension and barrel is caused to move as a unit from battery to recoil position, said connection means interconnecting said base member with said movable member so that movement of said base member from said one terminal position to its other terminal position initially causes disengagement of said locking member from said notch means and movement of said movable member to its in operative position, and means responsive to recoil of the barrel from battery toward recoil position to move said base member from said one terminal position on said barrel extension to said other terminal position while said barrel is recoiling for causing said connection means to effect first disengagement of said locking member from said notch means and then movement of said movable member from its operative position to its inoperative position while said barrel is recoiling.

5. In an automatic machine gun having a housing, a longitudinally movable barrel carried by said housing and a movable member carried within said housing for guided movement from a firing position adjacent said barrel to a loading position spaced from said barrel, releasable locking means on said movable member engageable with said barrel for releasably locking said movable member to said barrel when said movable member is at firing position, a base member engaged with said locking means and said movable member and movable from one terminal position where it causes said locking means to retain said movable member at firing position to another terminal position where it retains said movable member at loading position, and a hydraulic accelerator comprising, a fluid-filled chamber rigidly carried by said housing, a piston slideably carried within said chamber adjacent one end thereof for pressurizing the fluid upon actuation, p'iston actuating means rigidly carried by said barrel for actuating said piston and pressurizing the fiuid within said chamber in response to rearward recoil movement of said barrel, and actuating means connecting with said base member and responsive to the pressure generated in said fluid during said rearward recoil movement for forcefully moving said base member from said one terminal position to the other terminal position while said barrel is recoiling for first causing the release of said locking means and then movement of said movable member from firing position toward loading position while said barrel is recoiling.

6. In a machine gun having a housing, a longitudinally movable barrel carried by said housing and a breechblock carried within said housing for guided movement from a firing position adjacent said barrel to a loading position spaced from said barrel, a first hydrauliccylinder containing fluid, a driving piston clideably mounted in said first cylinder adjacent one end thereof for pressurizing said fluid upon displacement toward the other end of said first cylinder, a second hydraulic cylinder connected to said first hydraulic cylinder, a driven piston slideably mounted in second cylinder for displacement therein in response to pressurization of said fluid, means connecting said breechblock with said driven piston so that displacement of the latter causes said breechblock to be moved from firing to loading position, and hammer means rigidly carried by said barrel engageable with said driving piston during recoil movement of said barrel for displacing said driving piston toward said other end of said first cylinder and pressurizing said fluid whereby said driven piston is displaced and said breechblock is moved to loading position.

7. In the machine gun of claim 6, a buffer piston in said first cylinder, and a compressible buffer spring, pressurization of said fluid when said driving piston is displaced by said hammer means acting on said buffer piston to displace the same and compress said bufier spring for absorbing shock loads applied to said driven piston and for pressurizing said fluid after recoil movement of the barrel is completed.

8. An automaic machine gun comprising: a housing, a gun barrel having an axial chamber in which a cartridge is adapted to be fired, said barrel being axially slideable on said housing for recoil movement from a forward inbattery position to a rearward recoil position; a barrel extension rigidly attached to said barrel adjacent the chamber; a base member having a firing pin thereon and mounted on said barrel extension so that said firing pin is coaxial with said chamber, said base member being axially slideable on said barrel extension for movement from a rearward recoil position remote from the chamber to a forward firing position adjacent the chamber where the firing pin is adapted to strike and fire a cartridge; a driving Spring acting on said base member for urging the latter forwardly toward firing position; an accelerator on said housing engageable by said barrel extension during recoil movement of said barrel for moving said base member from firing position to recoil position against the action of said driving spring; a bolt block having an aperture therethrough and mounted on said barrel extension between said base member and said chamber so that said aperture is coaxial with said chamber, said firing .pin being slideably mounted in said aperture and said bolt block being axially slideable on said barrel extension for movement from a rearward recoil position remote from the chamber to a forward firing position abutting the chamber; a locking member hinged to said bolt :block 'for rotation from an inward position substantially parallel to said axis to an outward position inclined relative to said axis; and a pin on one member engaged in a slot in the other member to define a pinand-slot connection means that connects said base member to said locking member; said connection means causing said locking member to rotate to its outward position when said base member moves forwardly relative to said bolt block sufiiciently to project said tiring pin forwardly of said bolt block, said connection means causing said locking member to rotate to its inward position when said base member moves rearwardly away from said bolt block sufficiently to withdraw said firing pin into said bolt block, said connection means coupling said base member to said bolt block when said locking member is in its inward position for causing said bolt block to move with said base member when the latter moves rearwardly; said barrel extension having a side engageable with said locking member when said bolt block is between recoil and firing position for preventing said locking member from rotating to its outward position, said connection means coupling said bolt block to said base member when said locking member is prevented from rotating to its outward position by said side while said driving spring moves said base member forwardly toward firing position for causing said bolt block to move forwardly with said base member until said bolt block reaches firing position, said barrel extension having a notch which effects rotation of said locking member to its outward position when said bolt block is at firing position, movement by said driving spring of said base member to firing position when said bolt block is in firing position causing said connection means to rotate said locking member to its outward position and into said notch and said firing pin to slide forwardly in said aperture until it projects forwardly to said bolt block and fires a cartridge in said chamber, said locking member when in outward position in said notch preventing rearward movement of said bolt block toward its recoil position whereby said bolt block is attached to said barrel extension when a cartridge is fired, initial rearward movement of said base member by said accelerator from firing position toward recoil position causing said firing pin to slide rearwardly in said aperture until it is withdrawn into said bolt block and causing said connection means to rotate said locking member out of said notch to its inward position whereby said bolt block is detached from said barrel extension, further rearward movement of said base member by said accelerator to recoil position causing said connection means to couple said bolt block to said base member whereby said bolt blmk is moved rearwardly to recoil position by said base member.

References Cited in the file of this patent UNITED STATES PATENTS Home Ian. 14, 1902 Thompson Aug. 31, 1920 Marek May 2, 1933 Lahti Jan. 15, 1935 Chadwick et al. Nov. 16, 1948 FOREIGN PATENTS Great Britain Apr. 15, 1959