Automatic Gun Breech Mechanism Having Latches To Hold The Breech Block Open

Abstract

A reciprocating barrel is provided with a breech ring supporting a breech block for vertical and rotatable movement between open and closed positions of the firing chamber. The breech block is mounted on a pin having semi-circular end portions which are positioned within slots in the breech ring which control the vertical and rotational movement of the breech pin carrying the breech block. An actuator operated by explosion gases opens and closes the breech block. Breech latches hold the breech block in its open position, and ejector slides operated by the breech block serve to lock the latches so as to hold the breech block in the open position. The ejector slides are engaged by an incoming round of ammunition to release the latches and the breech block to allow the actuator to close the breech block for the next firing cycle.

Description

This invention relates to an automatic gun or cannon particularly adapted to provide a high rate of fire for relatively large caliber ammunition. More particularly, the application is related to an improved means for opening, holding open, releasing and closing a breech block.

The invention is related to a patent entitled Automatic Gun, Ser. No. 662,614 filed Aug. 23, 1967 by Eugene M. Stoner, now U.S. Pat. No. 3,500,718 issued on Mar. 17, 1970; and a patent entitled Automatic Gun with Ejection Actuated Rammer, Ser. No. 858,398 filed Sept. 16, 1969 by Eugene M. Stoner, now U.S. Pat. No. 3,584,532 issued on June 15, 1971.

In these earlier applications, a reciprocating gun barrel is driven by springs loaded by recoil forces from the previous firing. An ammunition receiver located to the rear of the barrel and aligned with the barrel guides a round of ammunition toward the barrel chamber as the round is propelled by a lightweight rammer mounted on the receiver. The rammer drives a round of ammunition forwardly into the barrel as the spent cartridge from the previous round is being ejected. Overlapping the rammer feeding cycle with the ejection of the spent cartridge provides high-speed operation and hence it is necessary that the breech block open and close smoothly and efficiently to attain the high-speed operation.

Also, it is important that the breech block be opened as soon as possible after a round is fired and that the breech block be positively closed as soon as the next round is chambered. It is also necessary that the breech block be arranged so that it is locked in its closed position and cannot be released until the round in the chamber has been fired. In the applications referred to above, the operation of the breech block is controlled by the position of the reciprocating barrel with respect to a fixed member supporting the barrel. While this approach is workable, it is somewhat indirect in that the breech block position is more directly related to the ammunition being chambered and fired and the cartridges being ejected. Accordingly it is desirable that the breech block operation be responsive to such functions.

In accordance with this invention, the breech block is opened by explosion gases, the opening of the breech block actuates latches for holding the breech block open, and the breech block is released by the next round being rammed into the barrel firing chamber.

More specifically, there is provided a breech ring attached to the barrel and a breech block supported within the breech ring movable between a vertical position closing the firing chamber and an open position permitting access to the firing chamber. The breech block is mounted on a pin having guide portions on the ends which have a cross-section that is a segment of a circle. These guide portions are positioned within a cam slot on each side of the breech block that includes a vertically oriented upper section with a width approximately equal to the radius of the guide portion, with the cross-section of the guide portion being sized so as to permit vertical movement of the breech block when the guide portions are properly oriented. Each cam slot includes a lower section open to the upper section and large enough to permit rotation of the breech block when a guide portion is in the lower section.

The breech block is moved to and from its open and closed position by an actuator piston operated by explosion gases of the previous round of ammunition. Since this piston is arranged to automatically close the breech block once it has been opened, there is provided a pair of pivotally mounted latches positioned on opposite sides of the breech block to hold the block in its open position. Ejector slides operated by the breech block as it is opened lock the latches in their breech block holding position. As the next round of ammunition is driven forwardly by the next round of ammunition, it moves the ejector slides in a manner to release the latches and hence allow the breech block to close.

For a more thorough understanding of the invention reference may be had to the following detailed description and drawings in which:

FIG. 1 is a plan view of an automatic gun incorporating the improvements of this invention;

FIG. 2 is a cross-sectional view on line 2--2 of FIG. 1 illustrating the rammer mechanism with a round of ammunition therein, and the breech section of the gun with the breech block open to receive the round;

FIG. 3 is an enlarged cross-sectional view of the breech section of the gun with a round of ammunition partially in the firing chamber and with the breech block open;

FIG. 4 is a fragmentary view illustrating in elevation a portion of the breech block and its mounting pin with the block in an open position as shown in FIG. 3;

FIG. 5 is an enlarged cross-section of the breech section of the gun similar to that of FIG. 3 only with the round fully chambered and the breech block in its closed position;

FIG. 6 is an enlarged fragmentary view in elevation of the breech block pin and breech block in the closed position as shown in FIG. 5;

FIG. 7 is an end elevational view on the line 7--7 of FIG. 2 showing the breech block in the open position, and a portion cut away to show the breech latches;

FIG. 8 is a view on line 8--8 of FIG. 2 taken in front of the breech latches showing the mounting of the breech ring in its supporting fixed member and showing the breech block opening buffer;

FIG. 9 is an enlarged cross-sectional view of the breech block opening buffer;

FIG. 10 is an exploded perspective view showing components of the buffer of FIG. 9;

FIG. 11 is an exploded perspective view of the breech block, the breech pin, the shoes for the pin, and the elements defining the cam slot for controlling movement of the pin;

FIG. 12 is a cross-sectional view on line 12--12 of FIG. 5 which illustrates the details of the mechanism for holding the breech block in an open position;

FIG. 13 is an enlarged cross-sectional view of a portion of the structure of FIG. 12 illustrating the ejector slides in their forward position;

FIG. 14 illustrates the ejector slides of FIG. 13 in their rearward position; and

FIG. 15 is a fragmentary cross-sectional view on line 15--15 of FIG. 4 showing the mounting of the breech block pin.

Referring first to FIG. 1, the gun may be considered to have several major assemblies including a barrel assembly 12; a breech ring assembly 14 attached to the rear of the barrel assembly; a fixed breech assembly 16, in which the combined barrel assembly and breech ring assembly are mounted for axial reciprocation; a drive spring assembly 17 connected between the fixed breech assembly and the combined barrel breech ring assembly; a rammer assembly 18 located to the rear of the fixed breech assembly 16 and axially aligned with the barrel assembly 12 for receiving a round of ammunition and for propelling the round forwardly into the barrel; and an ammunition feed mechanism 20 illustrated in phantom lines. The rear of the gun may be secured with a variety of mounts, depending on the use for the weapon. No particular mount is described herein, but for purposes of illustration, the fixed breech assembly 16 and the rammer assembly 18 are shown in FIG. 2 attached to a mounting plate 24 which in turn may be mounted for moving in suitable trunions (not shown).

RAMMER ASSEMBLY AND AMMUNITION FEED MECHANISM

Since the details of the rammer assembly and the feed mechanism do not form a part of the present invention, they will only be briefly described. Details of an ammunition feed mechanism may be had by reference to either of the two earlier mentioned applications. Details of the pneumatically operated rammer mechanism discussed below may be found in the second application referred to above. Referring to FIG. 2, the rammer mechanism 18 includes a tubular ammunition receiver 26 having an inner diameter adequate to receive a round of ammunition 28 shown positioned within the tube. While the gun can be made in a variety of sizes, the illustrated embodiment is designed for 35mm ammunition. The receiver 26 has openings on either side (not shown) for receiving ammunition from the feed mechanism 20. A pawl 30 mounted on the receiver positions the rear of the ammunition round 28.

The forward end of the receiver 26 is formed so that the upper portion is considerably shorter than the lower portion. This creates an outlet or port 27 between the tube and the breech block cam assembly 16 through which the empty cartridges are ejected. A cartridge deflector 38 having a forward curved surface extends completely across the front end of the receiver 26 and also extends somewhat above the receiver. This deflector is pivotally and slidably mounted on the forward end of the receiver to perform a variety of functions.

A rammer tube 40 is mounted on a back plate 42 and connected to a source of pressurized fluid not shown. A rammer piston 44 having a closed forward end is slidably mounted on the rammer tube 40 and includes an enlarged slider 44a carrying a pivotally mounted rammer pawl 46 which engages the rear of the round of ammunition 28. A spring 48 surrounds the forward end of the rammer piston 44 and extends between the enlarged portion 44a and a fixed support plate 50 in the forward portion of the rammer assembly. The rammer piston is mounted for slidable movement in its surrounding housing by suitable means not shown so that when high pressure air is applied to the rammer piston, the pawl 46 is driven forwardly driving a round of ammunition forwardly. A buffer assembly 52 includes a rearwardly extending piston 53 within the forward end of the spring 148 and the piston 53 is struck by the rammer piston at the end of its forward stroke to buffer and restrict is forward movement. The coil spring 48 returns the rammer piston 44 to its rearward position illustrated.

An elongated cylinder 54 is mounted on the upper part of the receiver 26 and supports a control rod 56 which extends forwardly from the cylinder 54 and engages the rear of the deflector 38. Movement of the control rod 56 as caused by the deflector 38 is utilized to control operation of the application of high pressure air to the rammer tube 40 and thus control of the ramming of shells forwardly towards the barrel. The remainder of the pneumatic control system is not shown in that it does not form a part of this invention. However, reference may be had to the later filed application mentioned above for such details if so desired.

BREECH SECTION AND SPRING CONNECTION

Refer now to FIGS. 2, 3, 7 and 8 as well as to FIG. 1 for a description of the breech section of the gun. A barrel 13 is shown in FIG. 2 with a firing chamber 32 without a round of ammunition positioned therein. In FIGS. 3 and 5 the round 28 is shown in the firing chamber. A breech ring 58 is shown attached to the rear of the barrel 13 by suitable circumferential ribs 58a on the ring and 13a on the barrel and by means of a pivotally mounted latch 60.

The fixed assembly 16 includes a large U-shaped fixed support member 62 which receives the breech ring 58 and the barrel 13 as may be seen from FIGS. 7 and 8. A pair of large keys 64 fit within mating grooves formed in the support member 62 and the breech ring 58 to slidably support the breech ring and barrel within the fixed support member 62.

The drive spring assemblies 17 positioned on each side of the barrel 13 are connected to react between the breech ring 58 and the support member 62 by being connected to outwardly extending lugs 59 shown in FIGS. 1 and 7 on the breech ring and lugs 66 shown in FIG. 1 on the U-shaped support member 62. The drive spring assemblies 17 are connected to urge the barrel to its forwardmost position so that as a round of ammunition is fired, and the barrel recoils rearwardly it is in opposition to the spring assembly, with the result that the springs drive the barrel forwardly after being loaded by the barrel being driven to its rearwardmost position.

BREECH BLOCK

Referring to FIGS. 2, 3 and 11, there is shown a breech block 68 keyed to a breech pin 70 which is supported by the breech ring 58. The breech pin 70 includes an inner portion 70a closest to the breech block 68 which has a completely circular cross-section, and an outer guide portion 70b that has a semi-circular cross-section. A square breech pin shoe 72 having an opening for receiving the circular portion 70a of the breech pin 70 is mounted for vertical reciprocation within a cam slot 74, which as seen in FIGS. 4 and 15, is in the inner wall of the breech ring 58. It should be understood that there is a shoe 72 on each side of the breech ring. The width of the slot 74 is just large enough to receive the width of the shoe 72; however, the height of the slot 74 is greater than the height of the shoe 72. Consequently, the shoe carrying the pin 70 and the breech block 68 may reciprocate vertically within the slot 74.

BREECH BLOCK CAM LOCK

Still referring to FIGS. 4 and 15, positioned outwardly from the slot 74 on each side of the breech ring is a second slot 76 whose forward edge 76a is an outward extension of the forward edge of the slot 74 while the rear edge of the slot 76 is positioned further to the rear than the rear edge of the slot 74. The height of the slot 76 is greater than the slot 74, their upper edges being at the same height but the lower edge of the slot 76 being below that of the slot 74. Within the slot 76 is positioned a cam lock element 78 having an upper leg 78a, a lower leg 78b and an interior edge 78c having somewhat of C-shape or semi-circular shape as may be seen in FIGS. 4 and 11. The width or front to rear dimension of the cam lock element 78 is less than the width of the slot 76 as may be seen from FIG. 4. Thus, the element 78 can reciprocate in a horizontal direction within the slot 76. However, the height of the element 76 is approximately equal to the height of the slot 76 so that the element 78 does not reciprocate vertically within the slot 76.

For urging the element 78 forwardly or to the right as viewed in FIG. 4, there is provided a pair of springs 81 having cylindrical caps 80 thereon that fit within mating sockets in the lock element 78. The springs 81 within the cups 80 urge the cam lock 78 toward the right so that the lower leg 78b engages the forward edge 76a of the slot 76. The forward edge 76a of the slot 76 is spaced from the forward edge 78b of the upper leg 78a of the element 78 so that together they define a vertically extending slot 79 slightly greater in width than the radius of the pin 70. Thus semi-circular guide portion 70b of the breech pin 70 can reciprocate within the slot 29 when the breech block is oriented in an upright position as shown in FIGS. 11 and FIG. 16. The edge 78d which is the rear wall of the slot 79, is approximately vertically aligned with or slightly to the rear of a vertical plane passing through the center of the breech pin 70. Since the interior edge 78c in the lower portion of the element 78 has a radius approximately equal to that of the breech pin guide portion 70b and this portion fits within the space defined by the edge 78c and the slot edge 76a, the breech pin guide portion 70b can rotate therein.

BREECH BLOCK ACTUATOR AND ACTUATOR BUFFER

Referring to FIG. 3, there is provided an actuator for opening and closing the breech block 68 including a cylinder 84 attached to the breech ring by the fastener 83. A central wall 84c and a tubular bumper 85 divides the cylinder into a forward chamber 84a and a rear buffer chamber 84b. A cylinder extension 86 is attached to the forward end of the cylinder 84 and defines a chamber 86a. Connections 87 attached to the forward end of the extension 86 lead to a source of pressurized air (not shown). A piston 88 extends through the bumper 85 and has formed on its forward end a piston head 89 which slides within the cylinder 84 and separates the chambers 84a and 86a.

The piston 88 has attached to its opposite end a connecting slide 90 by a key 88a. The slide 90 has spaced fingers which interleave with a pair of links 92 and a centrally positioned hammer 94, which is pivotally attached to the slide by a pivot pin 91. As may be seen from FIGS. 3 and 11, the other ends of the links 92 and the center of the hammer 94 are pivotally attached by a pin 93 to the lower end of the breech block 68. The hammer 94 extends upwardly into a slot 68a in the rear of the breech block 68 to engage a spring mounted firing pin 95. The slide 90 guides the piston rod 88 in its horizontal reciprocation by projections (not shown) which slide within grooves 107 in the breech ring 58.

Two columns of overlapping buffer ring springs 96 are positioned in the buffer chamber 84b of the cylinder 84 surrounding a portion of the piston 88. The forward end of the buffer ring columns engage the rear surface of the bumper 85 and the rear end of the buffer spring columns engage a rear tubular bumper 87 limited in its rearward movement by a cap 98 in the rear of the cylinder 84.

The chamber 84a within the cylinder 84 is connected by a passage 99 leading to an elongated conduit 100 positioned in a groove in the lower wall of the barrel 13, and leading to a port 101 shown in FIG. 2 which opens to the interior of the barrel 13. With such an arrangement, explosion gases are vented through the port 101 into the cylinder 84 so as to urge the piston 89 forwardly.

BARREL SEAR

Beneath the mechanism for operating the breech block is a pivotally mounted barrel sear 102 and a fluid operated actuator 104 having an output piston 103 connected through a link 105 to operate the barrel sear 102. The barrel sear cooperates with a suitable notch 106 in the breech ring, FIG. 4, for holding the barrel in its rearwardmost position when desired.

BREECH BLOCK BUFFER

For buffering the opening action of the breech block, there is provided a pair of buffers 110 as may be seen in FIG. 3 located at the rear of the breech section. Referring to FIGS. 9 and 10 the buffers include a buffer piston 112 positioned within a cylindrical chamber 113 formed within a housing 114 attached by suitable fasteners 114a to the breech ring 58. The housing 114 also is supported by the grooves in the breech ring. Two overlapping columns of buffer springs 115 extend between the head 112a of the buffer piston and the other end of the chamber 113. The buffer piston -112 has a forward portion 112b of rectangular cross-section which extends through an opening in the forward end of the chamber 113 and includes a recess 112c spaced from the forward end and having one wall defined by a downwardly and rearwardly sloping cam surface 112d.

As may be seen from FIGS. 8 and 10, a buffer plunger 116 is positioned between the forward portions 112b of the buffer pistons 112. The buffer plunger includes a pair of outwardly extending wings 116a which extend over the forward portions 112b of the pistons 112. The wings include depending portions 116b which fit within the recesses 112c and have lower surfaces defining downwardly and forwardly spacing cam surfaces 116c which engage the cam surfaces 112d of the plunger pistons 112. As can be appreciated by reference to FIGS. 9, 10 and 3, a downward force applied to the wings 116a on the buffer plunger 116 will cause the cam surfaces 112d and 116c to engage so that the vertical force applied to the plunger 116 is converted to a horizontal force applied to the buffer piston 112 and its rings 115 which buffer the force. To limit the upward movement of the plunger 116, there is provided a pair of outwardly extending pin stops 118 which are located below the piston forward portions 112b.

BREECH BLOCK LATCHES

For a description of the means for holding the breech block in its open position, refer now to FIGS. 7 and 12 where there is shown a pair of latches 120 mounted to pivot transversely with respect to the barrel axis on pins 121 in the breech ring on opposite sides of the breech block. The latches 120 include inwardly extending surfaces 120a which slope downwardly and inwardly to be engaged by the breech block as it is opening. The lower end of these surfaces 120a terminate in hook-like portions 120b which engage the leading edge of the breech block to hold the breech block in its open position as seen in FIG. 7. Spring loaded plungers 122 located on opposite sides of the breech ring are urged upwardly to bias the latches inwardly into the path of the breech block.

The forward surfaces 120d of the latches 120 are notched on the outer corner as shown at 124 by dotted lines in FIG. 7 and solid lines. Each latch has an outwardly extending projection 120c, FIG. 7, which rides within a groove 125 formed in the fixed member 62 as may be seen in FIG. 8. The groove extends below the level shown in FIG. 8 in a forward portion of the fixed member 62 to permit the latch hooks 12b to pivot outwardly.

EJECTOR SLIDES

The closing force introduced by the actuator piston 88 on the breech block is sufficient to overcome the inward force of the spring loaded plunger 122 so that the latches can be moved out of the path of the closing breech block. Accordingly, to lock the latches, there is provided a pair of ejector slides 130 which may be seen in FIGS. 12-14. These ejector slides 130 are slidably mounted in suitable axially extending grooves in the breech ring 58. The forward end of each ejector slide includes a spring loaded ejector lug 132 which extends inwardly into the annular groove 133 near the rim 133a at the end of the carriage 28, as may be seen in FIG. 13.

On the exterior of the ejector slide 130 there is positioned a detent 134 having conical outer surface which is urged outwardly by a spring 133. This conical outer surface on the detent 134 is adapted to mate with a suitable recess 136 formed in a detent plate 138 mounted in the wall of the breech ring 58.

An enlarged slot 140 is shown in FIGS. 3, 13 and 12 on the inner wall of the ejector slide adjacent the breech block. Within a transverse bore extending through the breech block, there is positioned a pair of pins 142 which are urged outwardly by a coil spring 144. The pins can also be seen in FIG. 11. The outer ends of these pins 142 slide within the slots 140 in the ejector slides 130 to move the slides rearwardly.

On the rear end of each ejector slide 130, there is positioned a locking tang 146 which extends rearwardly slightly further than the remainder of the ejector slide. This locking tang 146 is adapted to be received within the notch 124 on the forward face of the latch 120 when the latch is suitably positioned.

OPERATION

Assume that the gun is in the position shown in FIG. 2 wherein a shell 28 is positioned within the rammer receiver tube 26 and positioned to be rammed forwardly toward the barrel. No shell is in the barrel and the breech block 68 is held in open position. The breech block is urged into a closed position by compressed air in the chamber 86a in the cylinder extension 86 as shown in FIG. 3. Normally during operation of the gun this air is compressed by the piston 89 when the breech block is being opened; however, at the beginning cycle it may be necessary to apply compressed air through the fitting 87 to the chamber 86a to urge the breech block into the closed position. Preventing the breech block from closing is the pair of latches 120 which as seen in FIG. 7 has its hooks 120b engaging the upper surface of the breech block holding it in the open position. This condition is also shown in FIG. 3.

As mentioned, the closing force introduced by the piston 89 through the chamber 86a is normally sufficiently great such that the breech block could simply push the latches 120 out of the way against the urging of their spring loaded plungers 122, FIGS. 7. However, the latches 120 are held in their locking position by the ejector slides 130 which are in their rearwardmost position as shown in solid lines in FIG. 14. As may be seen, the tang 146 on the rear of the ejector 130 is within the notch 124 in the forward face of the breech block latch 120, thus preventing the latch from pivoting outwardly to release the breech block. The ejector slides 130 are held in this locking position by their spring loaded detents 134 received in the recess 136 as shown in full lines in FIG. 14.

To commence operation of the gun, compressed air is applied to the rammer tube 40 shown in FIG. 2 thus driving the rammer piston 44 carrying the pawl 47 and driving the round of ammunition 28 forwardly towards the barrel. The deflector 38 is pivoted upwardly by the shell, and the round is rammed into the barrel firing chamber. As the round 28 is being rammed forwardly, the barrel sear 102 is released by its pneumatic actuator 104, thus allowing the barrel to be driven forwardly by the spring assemblies 17, FIG. 1, which had been loaded by the previous firing or by suitable pneumatic or hydraulic means for first round operation. The round is thus driven into the barrel chamber as the barrel is moving forwardly and the breech block 68 is also closed as soon as the round is driven into the chamber.

In accordance with the invention, the breech block 68 is released and allowed to close by the round 28 at the point where it is almost completely chambered. Referring to FIGS. 3 and 13, as the round is driven into the chamber, it engages the forward surface of the inwardly extending lugs 132 on the extractor slides 130. Being spring loaded, the lugs 132 are forced outwardly out of the path of the shell until the annular groove 133 at the rear of the shell is passed by the lug 132, at which point the lug is pushed inwardly by its spring and causes the rear rim 133a on the cartridge 128. This causes the ejector slides 130 to be pulled forwardly by the round so that the rearwardly projecting tang 146 on the ejector slide 130 is withdrawn from the notch 124 in the breech latch 120, thus releasing the latches 120. It should be understood that the force applied to the ejector slide by the round is sufficient to force the detent 134 out of its mating recess 136.

With the latches released, the piston 89 and the piston rod 88 are forced rearwardly by the pressurized air within the chamber 86a. This force is applied through the links 92 attached to the base of the breech block. The force applied is both rearwardly and upwardly since the line of force is below the pivot pin 93 on the breech block. This results in a clockwise force as viewed in FIG. 3 causing the breech block to push the latches 120 outwardly and rotate into an upright position.

Note from FIG. 4 that the breech block pin 70 cannot move upwardly when the breech block is in a horizontal position because its guide portion 70b is in the lower semi-circular portion of the cam slot defined by the cam lock element 78, and oriented so that it interferes with the upper leg 78a of the element. It is necessary that the breech block be maintained in its lower position in that otherwise the upper end of the breech block would interfere with the depending lug 58b on the breech block ring as shown in FIGS. 3 and 5. Thus, the breech block must be first rotated to an upright position.

With the block in an upright position, the semi-circular guide portion 70b of the breech block pin70 is positioned as shown in FIGS. 11, 5 and 6 wherein it can be seen that the guide portion is now able to be received within the upper portion of the cam slot 79 shown in FIG. 4. In other words, the straight diametrical surface 70c of the guide portion is vertically oriented so that it faces the forward edge 78d of the leg 78a on the lock element 78. Consequently, the continued force applied through the piston 89 through the piston rod 88 and and slide 90 allows the breech block pin carrying the breech block 68 to slide upwardly on its shoes 72 within the cam slots 74 in which the shoes are positioned. Moving the breech block upwardly closes the rear of the firing chamber and locks the breech block in this position since its upward end engages the lug 58b on the breech ring 58 as may be seen in FIG. 5.

After the breech block pivots to an upright position, the latches 120 are once more pivoted inwardly by the plungers 122. This inward movement is limited by the outwardly extending projections 120c engaging the upper edge of the groove 125 in the support member 62.

The pivoting of the breech block through the links 92 also pivots the hammer 94, and as the breech block is closed, an overtravel of a piston 88 causes the hammer 94 to be pivoted a slight amount further so as to engage the firing pin 95 and thus detonate the round of ammunition 28.

Upon firing of the ammunition round, some of the explosion gases are vented through the port 101, FIG. 2, through the passage 100 and the conduit 99 into the chamber 84a in the cylinder 84 as viewed in FIG. 5. These high pressure gases immediately force the piston 89 forwardly thus applying a force on the link 92 connected to the breech block causing the movement of the breech block to be reversed so that it is once more returned to an open position. An initial movement can only be downward by virtue of the interference of the guide portions 70b on the breech block pin 70 with the elements 78 defining the cam slots 79. Since these elements 78 are not designed to take considerable amount of force, its spring loaded caps 80 enable the element 78 to move slightly to the rear, the cam slot 74 supporting the shoes 72 receiving the bulk of the thrust. As the breech block is pulled downwardly from its locked position, the guide portions 70b on the guide pin once more are moved into the lower portion of the slot as defined by the cam lock elements 78 and the adjacent slot wall so the breech block can then pivot to the open position as shown in FIGS. 3 and 4.

Referring now to FIGS. 12, 13 and 14, during the rotating opening movement of the breech block 68, the spring loaded pins 142 are moved in an arc in the slots 140 of the ejector slides 130 to move the slides rearwardly as shown by the arrow in FIG. 14. Since the extractor lugs 132 are engaging the rim 133a of the spent cartridge of the shell 28, this action withdraws the cartridge from the firing chamber. In actual practice, the force of the explosion is such that the explosion gases force the spent cartridge rearwardly at a high velocity so that the ejector slides are really not needed to withdraw the cartridge except in a misfire or jammed condition.

As the ejector slides are moved rearwardly by the spring loaded pins 142, the breech block latches 120 are being moved outwardly by the breech block against the urging of their spring loaded plungers 122 shown in FIG. 7. Consequently, the rearwardly extending tangs 146 on the ejector slides 130 engage the forward surface 120d of the latches 120 as indicated by broken lines in FIG. 14, thus preventing further movement of the ejector slides. In this temporarily stalled condition, the spring loaded detent 134 is positioned as shown by broken lines in FIG. 14 just at the entry to its mating recess 136. As the breech block 68 is moved to its completely open position, the breech latches 120 once more snap inwardly to the position shown in FIG. 7 so that its hooks 120b engage the upper surface of the breech block 68 to hold the breech block in the open position. To lock the latches in this latching position, the ejector slides 130 are now free to be moved rearwardly a further additional amount "x" indicated in FIG. 14 so that the slide tang 146 engages the notch 124 in the forward end of the latches 120 as shown in solid lines in FIG. 14. This additional amount is provided by the spring loaded detent 134 as it snaps into its mating recess 136. These various actions occur very quickly, of course, so that it is simply a continuous movement of the breech block opening and being locked in its open position.

As the ejector slides reach their rearwardmost position and the breech block continues to open each of the pins 142 carried by the breech block engage a suitable ramp 141, FIG. 3, on the slide 30 so as to force the pins 142 out of the slot 140 and inwardly into the breech block. This movement is reversed when the breech block closes.

Since the breech block is opened vary quickly, the overtravel of the excess force produced by the piston 88 is received by the buffer ring springs 96 as shown in FIG. 3. This prevents damage to the breech block and its linking mechanism. Also, as the breech block is snapped into its open position, its back surface engages the buffer plunger 116 shown in FIGS. 3 and 10. This downward force applied to the plunger 116 causes its cam surfaces 116c to forcefully engage the cam surfaces 112d on the buffer pistons 112 located in the housing 110 as seen in FIGS. 3, 7 and 9. The interaction of the cam surfaces 112d and 116c produces a forward force on the buffer piston 112 so as to compress the buffer ring springs 115 by virtue of the head 112a on the buffer piston. Thus the downward force is buffered by the buffer ring springs 115.

As will be appreciated, the air in the chamber 86a, FIG. 3, is compressed by the piston 89 during the breech block opening operation. The compression of this air also serves as a buffer spring for buffering the action of the opening force. In addition, this compressed air forms a "pneumatic spring" which is available as a source of energy to urge the breech block into a closed position for the next firing operation. It should be kept in mind that the firing of this gun is at a very rapid rate, such that there is very little time for the compressed air within the chamber 86a to be dissipated and sufficient air pressure is maintained to operate the breech block. As mentioned above, during a first round firing operation, external compressed air can be applied to the chamber for closing the breech block.

Referring to FIG. 2, the ejected cartridge of the round 28 which is moving rearwardly strikes the deflector 38 and is deflected upwardly out the ejector port 27. The movement of the deflector caused by the ejecting cartridge moves the rod 56 rearwardly to actuate the rammer piston 46 for ramming the next round of ammunition towards the barrel for the next firing cycle.

Claims

I claim:

1. In a gun having a barrel with a firing chamber therein, a breech ring attached to the barrel, and a breech block supported within the breech ring movable between a substantially vertical position closing the firing chamber and an open substantially horizontal position permitting access to the firing chamber, the improvements comprising:

a breech pin extending transversely through and fixed to the breech block, each end of the pin having a guide portion with a cross-section which is a segment of a circle;

said breech ring having means defining a cam slot on each side of the breech block for receiving said pin guide portions, said cam slots each having a vertically oriented upper section with a width approximately equal to the radius of said guide portion, the cross-section of the guide portion being sized so as to permit vertical movement of the breech block when the guide portions are properly oriented while preventing rotation of the pin, and said cam slots having a lower section open to the upper section and large enough to permit rotation of said pin breech block when the guide portions are positioned therein.

2. The gun of claim 1 including:

a second vertically oriented slot formed in said breech ring on each side of the breech block inwardly from said cam slot;

a shoe rotatably mounted on said breech pin inwardly from said guide portion on each side of the breech block positioned within said second slot, the shoe having a rectangular cross-section with a vertical dimension which is less than said second slot such that the shoe can reciprocate vertically within the second slot.

3. The gun of claim 1 wherein said breech block is in its vertical position closing the end of the firing chamber when said guide portions are aligned with said upper slot sections.

4. The gun of claim 3 wherein said guide portions have a semi-circular cross-section and the semi-circular surface of each guide portion faces toward the forward end of the gun when said guide portion is vertically oriented.

5. The gun of claim 1 wherein said lower section includes a rear edge of semi-circular curvature, the center of which is approximately vertically aligned with the rear edge of said upper slot section.

6. The gun of claim 1 wherein said means defining said cam slot includes a rectangular slot in the side wall of the breech ring, and a cam lock element positioned within said wall slot, the cam lock element being prevented from vertical movement by said wall slot, the cam lock element having somewhat a C-shaped interior with an upper leg being spaced from the forward edge of said wall slot to define said cam slot upper section, and a lower leg engaging said forward edge of said wall slot, the curved interior of said lock element in cooperation with said wall slot forward edge defining said cam slot lower section.

7. The gun of claim 6 wherein the width of said cam lock element is less than the width of said wall slot, and including spring means urging said cam lock element forwardly in a direction to maintain said lower leg in engagement with the forward edge of said wall slot.

8. The gun of claim 1 including a pair of breech latches movably mounted on said breech ring on opposite sides of the breech block, the latches having an inward position in the path of the breech block engaging the breech block in its open position to hold the breech block in its open position, and having an outward position out of the path of the breech block.

9. The gun of claim 8 including means for locking said breech latches in their inward position to prevent the breech block from forcing the breech latches outwardly.

10. In a gun having a barrel and breech ring attached thereto with a firing chamber formed therein, means supporting the barrel and breech ring, a breech block movable between a substantially vertical position closing the firing chamber and a substantially horizontal open position permitting access to the firing chamber and means locking said block in its closed position, the improvements comprising:

means supporting and guiding said breech block in said breech ring in a manner to permit it to move vertically into and out of its locked position only when properly oriented and to permit it to rotate between the open and closed positions only after the block is unlocked; and

means connected to said breech block for opening said breech block and operated by explosion gas produced by the firing of a round of ammunition, said opening means comprises a gas operated actuator having a piston attached to the lower end of the breech block and a piston head mounted on the other end of the piston positioned within a cylinder, with gas from the firing explosion being in communication with the cylinder in a manner such that explosion gas will drive the piston and move the breech block into its open position.

11. The gun of claim 10 wherein the cylinder surrounding said piston is closed on both ends, such that when the piston is moved to open the breech block, air is compressed between the other end of the cylinder and the piston, thus creating a "pneumatic spring" for urging said breech block into its closed position.

12. The gun of claim 11 including resilient buffer means associated with said piston rod to buffer the force of the piston movement at the ends of its stroke.

13. In an automatic gun having a barrel, a breech ring attached to the barrel, means supporting the barrel and breech ring in sliding reciprocation, and a breech block mounted for vertical and pivotal movement from a closed position to an open position within the breech ring, the improvements comprising:

an actuator operated by gas from an exploding round of ammunition connected to move the breech block from its closed position to its open position, said actuator includes a piston rod attached to the lower end of the breech block and a piston mounted on the opposite end of the rod positioned within a cylinder to form two chambers, one of the chambers being in communication with gases from an exploding round of ammunition in a manner to move the breech block into its open position.

14. The gun of claim 13 wherein the other chamber formed by the piston and cylinder is sealed so that as the piston is moved by the gases from an exploding round of ammunition, the air within said chamber is compressed, such compressed air being usable to close the breech block.

15. In a gun having a barrel with a firing chamber therein a breech ring attached to the barrel, a breech block supported within the breech ring to close the firing chamber and means for automatically opening and closing the breech block, the improvement comprising:

means operated by the opening movement of said breech block to latch the breech block in the open position, said latch means includes a pair of latches mounted on the breech ring, said latches being spring loaded into the path of the breech block and movable by the breech block out of the path of the breech block, and lock means responsive to opening movement of the breech block for locking the latches in their position holding the breech block in its open position.

16. The gun of claim 15 including means operated by a round of ammunition being advanced into the firing chamber for actuating the lock means to release said latch means, permitting the breech block to close.

17. In a gun having a barrel with a firing chamber therein a breech ring attached to the barrel, a breech block supported within the breech ring to close the firing chamber and means for automatically opening and closing the breech block, the improvement comprising:

means operated by the opening movement of said breech block to latch the breech block in the open position, said latch means includes a pair of latches pivotally mounted on opposite sides of the breech block on axes parallel to the barrel axis to be pivotable into and out of the path of the breech block.

18. The gun of claim 17 including:

a pair of ejector slides mounted within said breech ring for reciprocation on lines parallel to the barrel axis and positioned on opposite sides of the breech ring adjacent the breech latches, the slides including tangs which engage the latches to lock the latches in the path of the breech block holding the breech block in its open position.

19. The gun of claim 18 including a means carried by said breech block for moving said ejector slides rearwardly into engagement with the latches as the breech block is opening.

20. The gun of claim 19 including:

means carried by said slides for moving said ejector slides rearwardly an additional amount into locking engagement with the latches after the block is fully opened.

21. The gun of claim 19 wherein:

said breech latches are spring biased into the path of the breech block and are movable out of the path of the breech block by the breech block;

said ejector slides carry spring loaded detents which cooperate with mating sockets in the breech ring, the sockets being located such that the detents are just starting to enter the sockets when the ejector slides are initially moved rearwardly by the breech block and engage the latches as they are moved out of the path of the breech block, and the sockets and detents being sized such that the ejector slides are moved rearwardly a further additional amount by the bottoming of the detents in the sockets as the latches are snapped inwardly into the path of the breech block after it is open, the rear portions of the ejector slides entering notches in the latches as the latches move inwardly into the path of the breech block and the detents bottom in the sockets whereby the slides lock the latches in the path of the breech block.

22. The gun of claim 18 wherein said slides include spring loaded ejectors extending inwardly to engage a rear annular groove in the cartridge of a round of ammunition, the ejectors being oriented to be engaged by a round of ammunition as it is thrust forwardly into the barrel whereby the round drives the slides forwardly to release the latches and thus release the breech block allowing it to pivot into its closed position.

23. In a gun having a barrel with a firing chamber therein a breech ring attached to the barrel, a breech block supported within the breech ring to close the firing chamber and means for automatically opening and closing the breech block, the improvement comprising:

means operated by the opening movement of said breech block to latch the breech block in the open position;

said means for opening and closing the breech block including an actuator operated by the firing of the previous round of ammunition.

24. The gun of claim 23 wherein the actuator is operated by explosion gases from the firing of the previous round.

25. In a gun having a barrel with a firing chamber therein, a breech block, means for moving the breech block to open and close the firing chamber and locking means for holding the breech block open, the improvement comprising:

means operated by a round of ammunition being rammed into the firing chamber for releasing said locking means to allow said breech block to be closed, said releasing means includes a pair of ejector slides slidable in said gun adjacent the entry path to the firing chamber, said slides having spring loaded ejectors which extend into the path of said round of ammunition and are received in the annular groove in the rear of the cartridge of said round of ammunition so that the slides are moved by the round of ammunition, the movement of the slides being used to release the breech block.