US3763742A

US3763742A - Firing mechanism for firearm

Info

Publication number: US3763742A
Application number: US00267963A
Authority: US
Inventors: J Kotas; J Slattery
Original assignee: Individual
Current assignee: Desa International LLC; Remington Arms Co LLC
Priority date: 1972-06-30
Filing date: 1972-06-30
Publication date: 1973-10-09
Anticipated expiration: 1990-10-09

Abstract

A firing mechanism is provided which fires the firearm automatically as the breech block closes. The mechanism includes a hammer-engaging sear which is provided with a cam laterally offset from the sear, the cam being positioned above the operating arm for closing the breech block. As the operating arm is pivoted to close the breech block, it engages the cam and moves the sear to release the hammer.

Description

waited States Patent [191 Kotas et al.

[ Oct. 9, 1973 FIRING MECHANISM FOR FIREARM Inventors: John A. Kotas, Chicago Heights;

James V. Slattery, Oak Forest, both of Ill.

Filed: June 30, 1972 App]. No.: 267,963

US. Cl. 89/24, 89/27 R Int. Cl F4lf 11/02, F41f 13/04 Field of Search 42/14, 23, 24, 69 R;

References Cited UNITED STATES PATENTS Diaz 42/24 Primary Examiner-Stephen C. Bentley Attorney-John W. Chestnut et al.

[5 7] ABSTRACT A firing mechanism is provided which fires the firearm automatically as the breech block closes. The mechanism includes a hammer-engaging sear which is provided with a cam laterally offset from the sear, the cam being positioned above the operating arm for closing the breech block. As the operating arm is pivoted to close the breech block, it engages the cam and moves the sear to release the hammer.

9 Claims, 9 Drawing Figures PATENTED 91915 3.763.742

SHEET 10F 3 FIGJ v ,0

START 26 '7 sum 2 OF '3' PIC-3.3

F'IGA PATENTEU 91975 SHEET 3 BF 3 FIG.7

FIRING MECHANISM FOR FIREARM BACKGROUND This invention relates to a firing mechanism for firearms, and, more particularly, to a firing mechanism for firearms which include a breech block which is movable by an operating arm between unfired and fired posltions.

The invention finds particular utility in kiln guns such as described in co-owned U.S. Pat. Nos. 2,415,952 and 2,977,855 and will be described in conjunction therewith. As described in these patents, kiln guns conventionally include a vertically movable breech block which is movable between an open position in which a shell can be inserted into a shell chamber in the barrel and a fired or closed position in which the firing pin carried by the breech block is in position to strike the shell. The firing pin is actuated by a hammer, and the hammer is held in the ready to fire position by a scar. Heretofore, the sear has generally been disengaged from the hammer after the breech block is closed by pulling a lanyard connected to the sear or by a trigger. Firearms constructed in this manner require a two-step procedure to fire the gun after the shell is loaded. The breech block must first be closed, and then the sear must be released by pulling the lanyard or the trigger.

U.S. Pat. No. 2,977,855 discloses a means for releasing the sear as the breech block is closed, but this searreleasing means is not entirely satisfactory. A screw abutment for engaging the sear is carried by the breech block, and the adjustment of this screw abutment is rather critical since the screw must be positioned to release the sear exactly as the breech block reaches its fully closed position. If the sear was released prematurely, the shot misfired, and unless the adjustment was such that the releasing movement of the sear was initiated prior to the time the breech block stopped in its closed position, the sear might not release at all. Fur-' ther, even if the adjustment is proper, the relatively small contacting area between the screw and the sear is subject to wear, and the parts may lose their original setting.

SUMMARY The invention provides an automatic firing mechanism that releases the sear in timed relation to the closing of the breech block and which does not require adjustment once the initial timed relationship is set. The scar is provided with a cam which is directly engageable with the operating arm for the breech block, and the cam and the operating arm are engageable over substantially the entire width of the arm. Both the cam and the operating arm are formed of hardened steel, and the hard surfaces and the substantial extent of the engaging surfaces minimize wear of these parts. Since the parts are not adjustable, they are tamperproof and are not subject to human error. The cam is formed integrally with the sear, and the number of parts required for conventional guns is reduced. The automatic firing of the gun increases the speed of operation and reduces operating costs.

DESCRIPTION OF THE DRAWING The invention will be explained in conjunction with an illustrative embodiment shown in the accompanying drawing, in which:

FIG. 1 is a fragmentary side elevational view partially broken away, of a kiln gun equipped with the invention, the gun being shown in the ready to fire position;

FIG. 2 is a view similar to FIG. 1 showing the gun in the fired position;

FIG. 3 is an enlarged fragmentary sectional view taken along line 33 of FIG. 1;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3;

FIG. 5 is an enlarged perspective view of the camequipped sear;

FIG. 6 is another perspective view of the sear;

FIG. 7 is a side elevational view of the sear;

FIG. 8 is an end elevational view of the sear; and

FIG. 9 is a fragmentary plan view of the camming surface of the sear.

DESCRIPTION OF SPECIFIC EMBODIMENT Referring now to FIGS. 1 and 2, the numeral 10 designates a kiln gun generally of the type described in U.S. Pat. Nos. 2,415,952 and 2,977,855, to which reference may be had for details. The gun includes a frame or carriage 11 upon which are mounted a barrel l2 and a yoke 13. The barrel is threadedly secured to the yoke by barrel nut 14 and terminates adjacent a vertically extending breech block passage 15 (FIG. 3) provided through the yoke. A shell receiving chamber 16 in the barrel communicates with the breech passage An elongated vertically extending breech block 17 is slidably received by the breech block passage and carries a spring-retractable firing 18 which is mounted for horizontal sliding movement and a hammer 19 which is mounted for pivotal movement in a vertical plane. The hammer is mounted within a recess 20 in the rear of the breech block by a pin 21 and is urged to rotate toward the firing pin by a plunger 22 and spring 23 carried by the breech block.

The breech block can be moved vertically within the breech passage by means of an elongated operating arm 24 which is connected to shaft 25 for pivoting in a vertical plane. The shaft is rotatably mounted in the frame 11 and is rotatable by lever arm 26 which is connected thereto. The operating arm is provided with an elongated slot 27 which slidably receives a rotary stud shaft 28 extending transversely from the breech block, and as the operating arm is rotated by the lever arm, the breech block is caused to slide vertically within the yoke.

The upper end of the breech block is provided with a shell loading and ejecting channel 30 (FIG. 4) which will expose the shell-receiving chamber 16 of the barrel when the breech block is lowered to its loading position by rotating the lever arm clockwise to the position indicated in phantom in FIG. 1 at 26'. When the breech block is raised to its fired position illustrated in FIG. 2 by rotating the lever arm forwardly or counterclockwise, the firing pin 18 will be generally horizontally aligned with the shell casing.

A sear 31 is pivotally mounted within a recess 32 (FIGS. 3 and 4) in the yoke 13 by pivot pin 33, and the sear is urged to pivot forwardly, or clockwise as viewed in FIGS. 1 and 2, by a spring 34. One end of the spring is received in an opening 35 (FIGS. 6 and 8) in the rear of the sear, and the other end abuts the yoke.

The sear is shown in detail in FIGS. 5-9. The sear includes planar vertically extending

side surfaces

36 and 37, a curved front surface 38, and a rear surface 39. The upper portion of the sear extends forwardly to provide a hammer-engaging tooth 40, and the lower portion of the sear extends rearwardly to provide a stop foot 41 which is engageable with the yoke to prevent excessive forward rotation of the sear. A cam 42 extends laterally outwardly from the side surface 36 and includes a flat camming bottom surface 43, a Hat front surface 44 which extends generally perpendicularly to the surface 43, and a curved upper surface 45. The sear and cam are preferably formed integrally, as by casting, and a bore 46 extends through the cam and the sear for rotatably receiving the pivot pin 33.

Referring now to FIG. 4, the operating arm 24 extends alongside the breech block offset from a vertical center plane through the hammer, scar, and breech block and within a recessed or cutaway portion in the bottom of the breech block. The width of the operating arm and the width of the recess in the breech block are seen to be substantially the same, and the right side of the arm as viewed in FIG. 4 is substantially aligned with the right side of the upper non-recessed part of the breech block. The cam 42 extends laterally from the sear above the upper surface of the operating arm to such an extent that substantially the full width of the arm is engageable with the cam.

The gun is loaded by moving the lever arm 26 to the position shown in phantom at 26 in FIG. 1. This rearward movement of the lever arm rotates the operating arm 24 clockwise about the pivot provided by the shaft 25 and lowers the breech block to expose the cartridgereceiving chamber of the barrel. After the shell is inserted, the lever arm 26 is pushed forwardly to raise the breech block. When the tooth 47 of the hammer 19 engages the tooth 40 of the sear, further upward movement of the breech block will cause the hammer to pivot about its mounting pin 21 to depress the plunger 22 and spring 23. When the sear engages the hammer as illustrated in FIG. 1, the sear extends generally in the position shown in FIG. 7 in which the flat camming surface 43 extends angularly downwardly with respect to the horizontal.

The kiln gun is shown in its ready to fire position in FIG. 1. The hammer 19 has been engaged and cocked by the sear, the firing pin 18 is approaching horizontal alignment with the shell, and the top surface 48 of the operating arm 24 is just below the cam 42. As the lever arm 26 is rotated forwardly from the position shown in solid in FIG. 1, the top surface of the operating arm will engage the camming surface 43 of the cam and cause the sear to rotate clockwise about the mounting pin 33. The relationship between the camming surface and the operating arm is such that the sear will be rotated suffciently to release the hammer after the firing pin is raised sufficiently to strike the shell properly but before the operating arm reaches its upper limit of travel.

The kiln gun is shown in its fired position in FIG. 2. The operating arm has reached its fully raised position in which the upper surface thereof extends generally horizontally, the sear has been rotated clockwise to release the hammer, and the spring-actuated plunger 22 has swung the hammer into engagement with the firing pin 18.

As can be best seen in FIG. 4, the operating arm engages the cam across substantially the full width of the operating arm, and this substantial area of contact minimizes wear of these parts. Also, both the upper surface of the operating arm and the camming surface are flat, and even if the points of initial contact become worn, this will not affect the timed release of the hammer. When the operating arm reaches its upper limit of travel, the portion of the upper surface of the operating arm which engages the camming surface and the camming surface are substantially in facing contact.

I have found it advantageous to provide the sear and cam from hardened steel to further minimize wear, and in one specific embodiment the sear and cam were cast integrally from AISI 4330 steel and hardened to a Rockwell hardness of from about 48 to about 52. I have also found it advantageous to harden the operating arm, or at least the upper surface thereof, and in one specific embodiment the operating arm was cyanide hardened to a file hard surface. This permits some initial adjustment of the relationship between the operating arm and the cam. If the operating arm disengages the sear from the hammer prematurely, the upper surface of the operating arm can be filed away until the desired timed relationship is established. This initial adjustment can be made at the factory, and once it is made, no further adjustment is necessary or desired. Accordingly, the firing mechanism has no parts which can be misadjusted or tampered with by the user.

In one specific embodiment of the cam-equipped sear, the camming surface 43 extended at an angle of about 15 from the horizontal, and the flat surface 44 extended generally perpendicularly thereto. The camming surface was spaced about 0.240 inch from the center of the pivot opening 46 along a line extending perpendicularly to the camming surface and through the center of the pivot opening, and the length of the camming surface from the front surface 44 to this perpendicular line was about 0.275 inch. The tip of the cam at the juncture of the

surface

43 and 44 was therefore spaced about 0.268 inch vertically below the center of the pivot opening, and when the camming surface was rotated to a horizontal position by the operating arm, the camming surface would be positioned about 0.240 inch below the center of the opening, or about 0.028 inch above its lowermost point position in the ready to fire position. The lateral extent of the camming surface was about 0.605 inch, and the width of the operating arm was about 0.500 inch. The cam extended laterally above the operating arm for between one-half of the width of the arm to the full width thereof. The hammer-engaging surface of the tooth 40 was positioned about 0.705 inch from the center of the pivot opening, and the length of the hammer tooth 47 was about 0.10 inch, the length of the sear tooth being somewhat greater.

While in the foregoing specification a detailed description of a specific embodiment of the invention was set forth for the purpose of illustration, it is to be understood that many of the details herein given may be varied considerably by those skilled in the art without departing from the spirit and scope of the invention.

We claim:

1. In a firearm having a yoke provided with a vertical breech block passage, a barrel attached to the yoke and having a shell-receiving chamber communicating with the breech block passage, an elongated breech block vertically slidably received by the breech block passage, firing pin means carried by the breech block and movable between unfired and fired positions, the breech block being movable between an unfired position and a fired position in which the firing pin means is engageable with a shell received in the chamber, hammer means pivotally mounted in the breech block for movement between an unfired position and a fired position in which it engages the firing pin means, and spring means carried by the breech block for biasing the hammer means into the fired position and into engagement with the firing pin means to move the firing pin means from the unfired to the tired position, the improved firing mechanism comprising an elongated operating arm movably mounted on the firearm and extending adjacent the breech block, means connecting the operating arm and the breech block for causing vertical sliding movement of the breech block as the operating arm moves, a sear pivotally mounted on the yoke for movement between unfired and fired positions, the sear being engageable with the hammer means when both the sear and the hammer means are in the unfired position to hold the hammer means against the bias of the spring means, and a cam carried by the sear engageable with the operating arm as the operating arm moves the breech block to the fired position whereby the sear is pivoted to release the hammer means.

2. The structure of claim 1 in which the firing pin means, the hammer means and the sear are generally aligned for movement in a vertical plane through the breech block and the operating arm is movable in a plane generally parallel to said vertical plane and laterally offset therefrom, the cam extending laterally from the sear above the operating arm.

3. The structure of claim 2 in which the cam includes a substantially flat camming surface which extends at an acute angle from the horizontal when the sear is in the unfired position, the operating arm having a substantially flat upper surface engageable with the camming surface, the fiat upper surface of the operating arm extending at an acute angle from the horizontal when it first engages the camming surface and both the fiat upper surface and the camming surface extending generally horizontally when the sear is in the fired position.

4. The structure of claim 3 in which the camming surface extends at an angle of about 15 from the horizontal when the sear is in the unfired position.

5. The structure of claim 2 in which the cam includes a substantially flat camming surface which extends laterally from the sear above the operating arm, the operating arm having a substantially flat upper surface engageable with the camming surface for moving the sear from the unfired position to the fired position, the lateral extent of the engaging portions of the camming surface and the flat upper surface of the operating arm being at least about one-fourth inch.

6. The structure of claim 5 in which the camming surface and the flat upper surface of the operating arm are formed of hardened steel.

7. The structure of claim 6 in which the camming surface has a Rockwell hardness of about 48 to about 52.

8. The structure of claim 5 in which the sear and the cam are formed integrally.

9. The structure of claim 5 in which the sear and the cam are formed integrally by casting.

Claims

1. In a firearm having a yoke provided with a vertical breech block passage, a barrel attached to the yoke and having a shellreceiving chamber communicating with the breech block passage, an elongated breech block vertically slidably received by the breech block passage, firing pin means carried by the breech block and movable between unfired and fired positions, the breech block being movable between an unfired position and a fired position in which the firing pin means is engageable with a shell received in the chamber, hammer means pivotally mounted in the breech block for movement between an unfired position and a fired position in which it engages the firing pin means, and spring means carried by the breech block for biasing the hammer means into the fired position and into engagement with the firing pin means to move the firing pin means from the unfired to the fired position, the improved firing mechanism comprising an elongated operating arm movably mounted on the firearm and extending adjacent the breech block, means connecting the operating arm and the breech block for causing vertical sliding movement of the breech block as the operating arm moves, a sear pivotally mounted on the yoke for movement between unfired and fired positions, the sear being engageable with the hammer means when both the sear and the hammer means are in the unfired position to hold the hammer means against the bias of the spring means, and a cam carried by the sear engageable with the operating arm as the operating arm moves the breech block to the fired position whereby the sear is pivoted to release the hammer means.

3. The structure of claim 2 in which the cam includes a substantially flat cammIng surface which extends at an acute angle from the horizontal when the sear is in the unfired position, the operating arm having a substantially flat upper surface engageable with the camming surface, the flat upper surface of the operating arm extending at an acute angle from the horizontal when it first engages the camming surface and both the flat upper surface and the camming surface extending generally horizontally when the sear is in the fired position.

4. The structure of claim 3 in which the camming surface extends at an angle of about 15* from the horizontal when the sear is in the unfired position.