US3390609A - Firing mechanism for cannons - Google Patents

Description

y 1968 H. J. REEPMEYER 3,390,609

FIRING MECHANISM FOR CANNONS Filed Aug. 23. 1966 3 Sheets-Sheet 1 BEN- INVENTOR Hermun .l'Regpmgye'r ATTO-RNEY July 2, 1968 H. J. REEPMEYER 3,390,609

FIRING MECHANISM FOR CANNONS Filed Aug. 23. 1966 3 Sheets-Sheet 2 Eig .3

36 Fig E| INVENTOR Harman l Regpmgyar ATTOIRNEY July 2, 1968 H. J. REEPMEYER 3,390,609

FIRING MECHANISM FOR CANNONS Filed Aug. 23. 1966 3 Sheets-Sheet 5 INVENTOR Herman lReepmgrer ATTORNEY United States Patent 3,390,609 FIRING MECHANISM FOR CANNONS Herman J. Reepmeyer, Cohoes, N.Y., assignor to the United States of America as represented by the Secretary of the Army Filed Aug. 23, 1966, Ser. No. 574,874 2 Claims. (Cl. 89-27) ABSTRACT OF THE DISCLOSURE In a firing mechanism for cannons the firing pin is cocked and released by a straight pull on the lanyard with the sear located in a transverse shaft for rotational displacement therewith to cock the firing pin and translational displacement therein to release the firing pin. The end of the sear is cammingly contactable with a wall on the firing pin for converting rotational displacement of the sear with the shaft to translational retraction of the firing pin and the sear is so located respective to the wall that the angular relationship of the design axis of movement of the sear in the shaft to the wall increases as the firing pin is retracted so that a portion of the force applied by the sear to the wall is transmitted back to the sear for translational displacement to a position out of engagement with the wall for release of the firing pin.

This invention relates to cannons and pertains more particularly to the firing mechanisms thereof.

It has been the growing trend for the firing mechanisms of cannons to be automatically cocked and fired responsive to movement of the cannon as actuated by recoil forces. Trouble, however, is being experienced with such firing mechanisms inthat the firing pin is sometimes released before the breechblock is fully closed and locked. With those cannons which fire cartridge rounds this is not too serious as the percussion element in the cartridges is of rather small diameter so that the breechblock must be almost completely closed and locked in order for the firing pin to align with the percussion element.

In cannons, however, such as howitzers which use bagtype percussion elements having relatively large sensitive areas the firing pin can cause detonation before the breechblock is safely closed and locked. Consequently, it has been desirable for the firing mechanisms in such cannons to be manually actuated so that firing can be better controlled.

It is therefore one object of this invention to provide for cannons a manually actuated firing mechanism which is distinguished for its simplicity of operation and construction and which requires a minimum of machining in the breechblock for installation therein.

It is another object of this invention to provide such a firing mechanism which is easily and quickly replaced.

It is a further object of this invention to provide such a firing mechanism in which the firing pin is cocked and released by a continuous pull on a lanyard and which includes means for adjusting the position of attachment of the lanyard to the firing mechanism so that the firing mechanism can be actuated by direct pull of the lanyard from all quadrant elevations of the cannon.

It is still another object of this invention to provide such a firing mechanism in which the sear is displaceable both angularly and translationally by pull on the lanyard to reduce the amount of displacement required thereof to fire the cannon.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

3,399,509 Patented July 2, 1968 "ice FIG. 1 is an elevational view of the breechblock of a cannon;

FIG. 2 is an enlarged view taken along line 22 of FIG. 1;

FIG. 3 is an enlarged view taken along line 3-3 of FIG. 2 and shows the firing mechanism with all the members in their static positions;

FIG. 4 is a view similar to FIG. 3 but showing the firing pin partially retracted by angular displacement of the sear and the sear partially displaced translationally to its release position;

FIG. 5 is a view similar to FIGS. 3 and 4 but showing the accelerating member released from the sear and the striking member impelled forwardly by its inertia to the firing position;

FIG. 6 is an enlarged view taken along line 66 of FIG. 2; and

FIG. 7 is a perspective View of the extending end of the actuating device shaft and the adjustable ring mounted thereon.

Shown in the figures is a cannon 12 such as the mm. Howitzer XM138 which is provided with a laterally displaceable breechblock 14. Formed in breechblock 14 is a longitudinal bore 16 and a transverse bore 13 for mounting a firing mechanism 20. The axis of bore 18 transverses breechblock 14 below that of bore 16 and such bores are arranged to intersect to form a communicating mouth 21 therebetween, as shown in FIG. 2.

Bore i6 is of stepped configuration and includes a rear section 22 which extends forwardly from the rear face of breechblock 14 to an annular shoulder 24, a second section 26 of smaller diameter which extends from shoulder 24 to another shoulder 28, a third section 30 of still smaller diameter which extends from shoulder 28 to a shoulder 32, and a front section 34 leading from the third section to the front face of the breechblock.

Bore 16 houses a firing pin assembly 36 for discharge of a barrel chambered round and includes an accelerating member 38 and an inertial striking member 40. Accelerating member 38 is received by rear section 22 for sliding displacement between a retracted .position and a forward position wherein the front end of the accelerating member is in contact with shoulder 24. A spring 42 is disposed between a rearwardly facing shoulder 44 on accelerating member 38 and a retainer 46, arranged to releasably block the rear end of bore 16, whereby the accelerating member is biased to its forward position. An annular channel 48 is formed in accelerating member 38 forwardly of a circumferential area 50. Channel 48 is of rectangular configuration in cross section and includes a rear wall 51 which is normal to the axis of accelerating member 38.

Striking member 48 is slidingly received by second section 26 for displacement between a retracted position and a firing position wherein a forwardly facing shoulder 52 on the striking member is in contact with shoulder 2-8 in bore 16. A spring 54 is disposed between shoulder 52 on striking member 49 and shoulder 32 of bore 16 for biasing the striking member to its retracted position, Striking member 40 includes a forwardly extending pin 58 which is arranged to project from the front face of breechblock 14 for firing a chambered round when the striking member is in its firing position.

Striking member 40 also includes an axial shank 60 which extends rearwardly so as to be slidingly received by a mating hole 62 in the front end of accelerating member 38. A pin 64 extends transversely through the front end of accelerating member 38 so as to pass through hole 62 and a longitudinally elongated slot 66 through shank 60 to join striking member 40 to accelerating member 38 yet permit limited relative movement therebetween. Shank is terminated by an end 68 which is contactable by a. bottom wall 69 of hole 62 for transferring forward displacement of accelerating member 38 to striking member 40.

Bore 18 mounts an actuating device 70 for manually actuating firing pin assembly 36. Actuating device 70 includes a shaft 72 rotatingly journaled in core l8 and such shaft carries a sear 74 of blade configuration which is slidingly mounted in an accommodating ilOt 76 for radial displacement relative to the shaft between an outer engaging position and an inner release position along a design axis of movement, noted at .t.t' in FIG. 4. A spring 78 biases sear 74 to its engaging position and the displacement of the sear is limited through the cooperation of a pin 80 through shaft 72 with an elongated slot 82 in the sear.

When in its engaging position, sear 74 extends from shaft 72 through mouth 21 for engagement with channel 48 so that rotation of shaft 72 in a direction to press an extending end 84 of the sear against rear wall 51 of the channel actuates accelerating member 38 into its retracted position. Extending end 84 of seal 74 inclines outwardly and rearwardly from the front face thereof and a radius 86 is formed where the outer face of the sear oins the rear face thereof.

A section 88 at one end of shaft 72 pro ects from breechblock 14 through a collar 90 which 18 tixed as by bolt means to the respective side thereof. A pin 92 extends from section 88 into a radial opening 94 in collar 90 and such opening is formed as noted in FIG. b. so as to cooperate with the pin in preventing axial displacement of shaft 72 while permitting sutficient rotation thereof for angular displacement of sear 74 from .1 normal position, wherein extending end 84 of the sear is received by channel 48 when accelerating member .38 is in its forward position, to a disengaged position wherein the extending end is withdrawn from the channel when the accelerating member is displaced thereby to its retracted position.

Rotatingly mounted on the end or section 88 is a ring 96 having a radially projecting ear 98 with an orifice for attachment of a lanyard 100. Ring 96 is adiustably engaged =with shaft 72 by engagement of the extending ends of a rod 102 mounted through section 88 with a selected pair of a plurality of angularly related grooves llt34 formed in the outside face of the ring, as shown in FIG.

A torsion-compression spring 196 is mounted over section 88 between collar 90 and ring 96 with one end anchored to the ring and the opposite end anchored to the collar. Thus, ring 96 is pressed by spring 106 outwardly, respective to breechblock 14, to firmly engage rod 102 with a selected pair of the grooves 104 and thereby engage the ring to shaft 72. When the angular position of ring 96 respective to shaft 72 needs to be changed so that the shaft may be rotated by a direct pull on lanyard N0, the ring is pressed inwardly until the engaged grooves ill-4 are free of rod 102 and then the ring is free to be rotated to the desired position. Release of ring '96 permits engagement of rod 102 with the nearest pair of grooves 104 through the bias of spring 106. With the opposite ends of spring 106 anchored to collar 90 and ring 96 and rod 102 engaged with a pair of the grooves 164, the torsion of the spring is transferred from the ring to the shaft which is thereby biased angularly to locate sear 74 in its normal position, as shown in FIG. 2.

Referring to FIGS, 3-5, it is seen that when sear 74 is displaced angularly by shaft 72 from its normal to its disengaged position, radius 86 contacts rear wall 51 and axis of movement xx of the sear in the shaft is so angularly related to the end wall, as seen in FIG. 4. that the pressure of the radius against the end wall. by the pull on the lanyard against the tension of spring 42, causes the sear to be translationally displaced inwardly to its release position. Thus, the angular displacement of shaft 72 required to disengage sear 74 from tiring pin assembly 4 i6 is less than that which would be required if the sear was not also radially displaceable in the shaft.

Operation When breechblock 14 is closed and cannon 12 is ready to be tired, actuating mechanism 70, as shown in FIG. 3, is biased by spring 106 so that sear '74 is located in its normal position and is extended by spring 78 to its engaging position respective to channel 48; accelerating member 38 is biased by spring 42 to its forward position; and striking member 40 is biased by spring 54 to its retracted position.

When cannon 12 is to be fired, lanyard is pulled, causing shaft 72 to be rotated whereupon extending end 84 of sear 74 contacts rear wall 51 to retract accelerating member .38 rearwardly from its forward position. lContinuing pull on lanyard 100 moves radius 86 on sear 74 into contact with rear wall 51 and the axis of movement .t.r of the sear becomes angularly positioned relative to the rear wall so that as the sear moves accelerating member .38 rearwardly it is simultaneously cammed inwardly to its release position. Also, while accelerating member .38 is displaced rearwardly so that bottom wall li9 draws away from end 66 striking member 40 follows, under the bias of spring 54.

When sear 74 is entirely disengaged from rear wall 51, accelerating member 38 is free to be impelled forwardly by energized spring 42 to its forward position. Striking member 40 is propelled forwardly by accelerating member .38 and when the accelerating member is stopped in its forward position by contact of the front end thereof with shoulder 24 of bore 16, striking member 40 continues on under its inertia to its striking position to fire the chambered cartridge. Immediately upon striking member 40 being stopped in its striking position the tension cf the compressed spring 54 returns it to its retracted position relative to accelerating member 38 whereby pin 58 is retracted within breechblock 14 and so cannot be damaged when the breechblock is opened for chambering another round.

When accelerating member 38 was released by sear 74, and was impelled forwardly, the sear was held in its release position by contact of extending end 84 thereof with circumferential area 50. After cannon 12 is fired and lanyard 100 is released, actuating device 70 is rotated back to its normal position by spring 106 and when sear 74 comes into registry with channel 48 it automatically snaps thereinto so that firing mechanism 20 is ready to fire another round.

From the foregoing it is readily apparent that there is provided herein for cannons a manually actuated firing mechanism which is simple in design and positive in operation, which requires a minimum of machining in the breechblock for installation therein, is easily adjustable to rovide direct pull on the lanyard for all quadrant elevations of the cannon and which provides a minimum of displacement of the lanyard for cocking and releasing the tiring pin.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

ll claim:

l. in a cannon having a breechblock, a firing mechanism including a tiring pin assembly, an accelerating member cf said tiring pin assembly disposed for longitudinal displacement in the breechblock between a retracted and a forward position, means for biasing said accelerating member to the forward position, an actuating device provided with a shaft transversely mounted in the breechblock for rotational displacement therein, a sear mounted in said shaft for translational displacement therein between an engaging and a release position along a design axis of movement and for angular displacement with said shaft between a normal and a disengaged position, an extending end of said sear, a spring for biasing said sear to the engaging position, spring means operationally disposed between the breechblock and said shaft to produce a torque for biasing said shaft in a direction to displace said sear angularly to the normal position, an annular channel formed in said accelerating member for receiving said extending end of said sear when in the normal position, a rear wall formed by said channel and arranged for contact by said extending end of said sear during angular displacement thereof from the normal position to actuate said accelerating member to the retracted position, a radius formed on said extending end of said sear and disposed for camming contact with said wall during displacement of said sear to the disengaged position, said shaft being so positioned in the breechblock respective to said rear wall that rotation of said sear by said shaft from the normal position for actuating said accelerating member to the retracted position increases the angular relationship of the design axis of movement of said sear to said rear wall so as to transmit a part of the force applied by said sear to said rear wall back to said sear for translational actuation thereof against the bias of said spring to the disengaged position.

2. The invention as defined in claim 1 wherein said shaft includes a section extending outside the breechblock, said actuating device includes a rod extending through the extending section of said shaft, a ring mounted for angular and axial displacement on the extending end of said shaft a plurality of angularly related grooves formed in the outside of said ring so as to be selectively alignable with extending ends of said rod when said ring is rotated for adjusting the angular position thereof on said shaft, and an ear extending from the circumference of said ring for connecting a lanyard thereto, and wherein said spring means operationally disposed between the breechblock and said shaft is of torsion-compression type and is mounted one the extending section of said shaft between the breechblock and said ring and anchored at opposite ends thereto for simultaneously biasing said ring away from the breechblock to engage the selected ones of said grooves with said rod and thereby connect said ring with said shaft at the adjusted position and bias said shaft angularly to return said sear to the normal position.

References Cited UNITED STATES PATENTS 687,332 11/1901 Noble 8927 2,503,309 4/1950 Weiss 8927 2,504,162 4/1950 Summerbell et a1 8927 FOREIGN PATENTS 4,839 1894 Great Britain.

BENJAMIN A. BORCHELT, Primary Examiner.

S. C. BENTLEY, Assistant Examiner.

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