US2756635A - Multi-leaf torsion spring for closing a breechblock - Google Patents

Description

July 31, 1956 M. J. ENGEL ETAL 2,755,635

MULTI-LEAF TORSION SPRING FOR CLOSING A BREEICHBLOCK Filed Dec. 21, 1954 4 Sheets-Sheet. 1

INVENTOR. Marvin J .Enge. l wan 11 Hngpss Jul-1n B-5fl1e.ry

wi iiwwazaw July 31, 1956 M. J. ENGEL HAL 2,756,635

MULTI-LEAF TORSION SPRING FOR CLOSING A BREECHBLOCK Filed Dec. 21, 1954 4 Sheets-Sheet 2 INVENTOR. Marvin J- Engel [Ivan llHcn pasl John E1 5ille.ry

R TTOENE'YG 4 Sheets-Sheet 3 M. J. ENGEL ETAL MULTI-LEAF TORSION SPRING FOR CLOSING A BREECHBLOCK July 31, 1956 Filed Dec. 21, 1954 5 Y m1 5 Ta N N 5 z fi m m r J. H

MEIVII'L Swan 1] Hal: JCIhTL ELElxll BY 9%5M1QMV QMQLW- July 31, 1956 M. J. ENGEL ETAL MULTI-LEAF TORSION SPRING FOR CLOSING A BREECHBLOCK 4 Sheets-Sheet.

Filed Dec. 21, 1954 Mm M15 5 MAP. Wm Vnma d mE u 1T Hwm n m Wm Mob 5 2,756,635 Patented July 31, 1956 MULTI-LEAF TORSION SPRING FOR CLOSING A BREECHBLOCK Marvin J. Engel, Albany, Owen D. Hoopes, Latham, and John B. Sillery, Albany, N. Y., assignors to the United States of America as represented by the Secretary of the Army Application December 21, 1954, Serial No. 476,861 3 Claims. (Cl. 8917) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to breech mechanisms for firearms and more particularly to the spring means for closing the breechblock member thereof.

In designing those guns which are to be mounted in combat vehicles such as tanks, the limited space available inside of the turrets necessitates a continuing effort to reduce the size of the weapons without sacrificing fire power.

One of the most space consuming of the components of a cannon located within a turret is the breech mechanism which requires cooperating mechanical linkages, springs and arrangements of components to perform its function of opening the chamber of the gun tube for the extraction of a spent cartridge case and the loading of a live round and of closing the chamber for the firing of the round.

In virtually all cannons used in tanks, the breechblocks are opened by using the energy of gun recoil or counterrecoil to rotate a crank which lowers the breechblock to an open position and at the same time ejects the spent cartridge case and energizes a spring device linked to the breechblock. The spring retains the stored energy until the breechblock is released for closing by a newly chambered round which trips the extractors holding the breechblock in open position, at which time the automatically released energy of the spring closes the breechblock to make the gun ready for fire.

Many types of springs have been used for this purpose. The one most commonly used is a straight helical compression spring, but this arrangement utilizes a large amount of space because of the separate housing required for the spring and the cooperating linkages located along side the breech. Clock springs have also been used, but again the space ratio of spring to breech is on the high side. Torsion helical springs of both square and round highly stressed wire have been used successfully for reducing the amount of occupying space per unit of energy, but the space gain is accomplished through the use of critical material which in applications for cannons of larger caliber than 75 mm. is prohibitive. The use of lower strength wire means that working stresses must be lowered, consequently the spring increases in size and its advantage in compactness becomes lessened.

A solid bar of either round or rectangular cross-section enables a large amount of energy to be stored in a small space when subject to angular movement, but the angular movement allowable before plastic flow starts is much too small to effectively close the breech of a gun.

It is the object of this invention to provide for the breech mechanism of a firearm a torsional spring device for closing the breechblock unit which has the advantage of the space gain provided by a torsional bar spring, yet may be operated through an angular movement suflicient to close the breechblock without being over-stressed, and

the further advantage of being formed from readily available, non-critical material.

It is another object of this invention to provide for the breech mechanism of firearms a space saving spring for closing the breechblock of a firearm which is comprised of a plurality of thin leaves stacked to form a torsional spring of rectangular cross-section. Thus, each leaf acts as an independent torsion bar, subject to torsional load about its longitudinal axis of symmetry, and by this distribution of load the stress in the torsional spring for any given angular twist is reduced.

It is a further object of this invention to provide for the breech mechanism of firearms a torsional bar spring for closing the breechblock which is adjustable to any desired torsional moment.

It is a still further object of this invention to provide for the breech mechanism of firearms a spring for closing the breechblock which is mountable within the operating shaft and so does not occupy any space in addition to the designed configuration of the operating components and which provides a more nearly symmetrical breech mechanism.

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:

Fig. l is a view showing the rear end of a cannon;

Fig. 2 is an enlarged view taken along line 2-2 of Fig. 1;

Fig. 3 .is an enlarged rear end view of the cannon partially broken away to show the angular relationship of the breechblock closing spring when the breechblock is in open position;

Fig. 4 is an exploded perspective view of the breechblock operating mechanism;

Fig. 5 is an enlarged view taken along line 5-5 of Fig. 1;

Fig. 6 is an enlarged side view showing the operating crank at point of engagement with the ejector cam during counterrecoil of the cannon;

Fig. 7 is a view taken along line 7-7 of Fig. 6;

Fig. 8 is an enlarged side view showing the breechblock operated to open position by the engagement of the operating crank with the ejector cam during counterrecoil of the cannon;

Fig. 9 is a view taken along line 99 of Fig. 8

Fig. 10 is an enlarged fragmentary view showing the ejector cam in normal position in relationship to the gun mount;

Fig. 11 is a view similar to Fig. 10 but showing the ejector cam biased inwardly by the operating crank during recoil of the cannon;

Fig. 12 is an enlarged cam; and

Fig. 13 is an enlarged perspective exploded view of the adjusting device.

Shown in the figures is a breech mechanism of a slide block cannon including a breech ring 12 and a breechblock 14 mounted for slidable movement therein on ways (not shown). Depending from the bottom of brech ring 12 is a left lug 18 and a right lug 20 spaced laterally therefrom. Right lug 20 is provided with a bore 22 which is counterbored, as noted at 23, to rotatably receive an adjustor member 24 having a cylindrical portion 26 received within such counterbore and a larger diameter portion 28 which engages the right side of such lug. Extending through adjustor member 24, symmetrical with the axisthereof, is a rectangular opening 32, which is chamfered, as noted at 33, at the end inside of portion 26. 'A set screw 34 is threadably mounted through right lug 20 to be received by an annular groove 36 around portion 26 whereby adjustor member 24 is rotatable in perspective view of the ejector "rnent. Aptunger 27 is slidably mounted in "breech ring 12 in back of portion 28 and is biased against such portion by a coil spring 30. Plunger.27 is receivable by a cooperating notch '31 in portion 28 which notch is. provided with aplurality of step portions asbest shown in'Fi'g. 13

*to provide the means for selectively adjusting the rotatable position of 'adjustor member 24.

Left lug 18 is'bored, as -noted at 37, to receive a cylindfi'c'al shaft 38having a bearing portion 42 rotatably received by'such boreand a reduced diameter axle portion 40 which =extendsffromsuch bearing portion to be 'rotatablyreceive'd'bybore 22. The end of bearing portion 42 adjacent axle portion 40 is cut back to form a semi-annular recess 46 for receiving a .key portion 'as "hereinafter noted. Shaft 38 extends beyond left lug 18 andprovidedon 'suchexte'nding' portion is an'opera'ting 'cr'ank 48h'aving an integral hub 50' which is spaced from the adjacent side of left lug 18 "by a cylindrical flange 'porti'on'52. A' set screw 54 mounted threadably through left'lug "18 is received by an annular groove 56 around be'aring'portion "42 to secureshaft 38 against lateral displacement while being rotatable.

"Extending radially from 'hub50 are a protruding portion'58 and an integral arm 60. A stud 62 extends laterally outward from arm 60 to be engageable during counterrecoil of breech ring 12 with a conventional ejector cam "64mounted on a gun m'ount66 for rotation of shaft '38. Ejector ca1n*64, of conventional design and operation, is spring-biased outwardly from mount to an operating crank engaging p'osition'by a cooperating'spring 65, whereby stud 62, during the recoil portion of the operating cycle, engageably actuates such cam inwardly, -to ride thereover. An operating handle 68 is rotatably mounted on flange portion 52 and is provided with a p1unger70 receivable by a radial "slot '72 in'protruding portion 58 to engage such handle to shaft 38 when manual operation thereof is desired.

Mounted on axle portion '40 is a breechblock crank 74 having a hub portion 76, which is bored as noted at 78 to receive such axle portion, and an arcuate arm portion 3 80- extending therefrom. A semiannular key portion 82 projects from hub portion 76 to mate with recess 46 whereby breechblock crank 74 is engaged for unitary rotation'with shaft 38' and is arranged to extend from shaft 38 in approximately the same direction as operating crank 48. A hollow cylindrical spacer 84 is mounted on axle portion 40 between right lug 20 and breechblock crank 74 for maintaining key portion 82 thereon in recess 46. Extending laterally through the free end of arm 80 is a 'cross-head-pivot pin 86 which is mounted therein to extend beyond both sides of such arm, as noted at 88.

Rotatably mounted on extending portions 88 of pin 86 -is a pair'of cylindrical cross-heads 90 which are slidably received in a pair1ofdiagonal grooves 92' in breechblock 14. Whereby, rotation of shaft'38 causes breechblock "crank 74 to camrningly raise such breechblock to a close position or to lower such breechblock to an open position. Extending'into shaft 38 from the end of axle portion 40 thereof is an axial hole 94 which is terminated by a rectangular mouth portion 96 symmetrical therewith.

Extending through mouth portion 96 and opening 32 in adjustor member 24 is a'tor'sional-spring 98 of rectangular cross-section which is comprised of a plurality of stacked spring leaves 99. Mouth portion 96 and opening 32 are so dimensioned that the wallsthereof adjacent the top and bottom ones of the stacked spring leaves 99 are in close engagement therewith with clearances provided between the edges of such spring leaves and the walls of suchmouth portion and opening. -A driving pin 100 is mounted-diametrically through base-portion 50 of operating crank-48 to'passthrough aligned cylindrical holes 102-provide'd in one endof leaves'99. A retaining pin 3504 is slid-ably mounted diametrically through portion 2610f adjuster. member'24 to pass through alignedelon- "seat itself therein.

Rotation of operating crank 48 by the engagarnent of stud 62 with ejector cam 64 rotates shaft 38 to lower breechblock 14 to openposition and at the same time twists torsional spring 98 to store energy therein for closing such breechblock. The elongations of holes 106 permit longitudinal displacement of leaves 99 when twisted and the clearances between the edges of spring leaves 99 and the adjacent walls of mouth portion 96 and opening 32 permit angular displacement'of such leaves about pin 100 and retaining pin 104, as best noted in Fig. 9 due to the helix angle produced when such spring leaves are twisted. Thus, there isiniparted to spring 98 as near a true torsional load as is possible. Four equally spaced holes 108 are provided in the outer face of adjuster member 24 to permit the use of a conventional spanner wrench'for turning such adjustor memher to adjust the preload of torsional bar spring 98 and thereby assure the closing of breechblock 14 when releasedfrom open position. Such adjustment is possible through the cooperation of plunger'27 with the step portions 35 of notch 31 which are arranged to become progress'ively of lesser'depth in'the direction which spring 98 applies force to shaft '38 for raising'breechblock 14 to blocking position. 'To increase the preload in spring '98, adjustor member 24is rotated by a spanner in the direction of the applied force of such springuntil the 'nextone of the step portions -35 aligns with plunger 27 which, through the bias of spring 30, will automatically To back-off the preload, plunger 27 is depressed a sufficient lateral distance to clear the undesired one of the step-portions 35 whereby the preload in spring 98 will automatically rotate adjuster member 24 to engage the next shallower one of the step portions 35 with such plunger.

Operation .such stud to ride over such cam. During the ensuing counterrecoil of breech ring 12, stud 62 engages the now outwardly projecting rear end of ejector cam 64 whereby operating crank 48 is turned, rotating shaft38 which is integral therewith.

Rotation of shaft 38 causes simultaneousrotation of breechblock crank 74 .which is engaged for simultaneous rotation therewith by the engagement of key portion 82 of such breechblock crank with recess 46 in bearing portion 42 of such shaft. Whereby, cross-heads are moved along grooves 92 in breechblock 14 during rotation of breechblock crank'74 to camniingly lower such breechblock in breech ring 12 to open position. When breechblock 14' is in open position, a pair of conventionally operating extractors (not shown), which have expelled the spent cartridge case from the cannon during the opening of such breechblock, lock such'breechblock in the open position.

During rotation of shaft same endfof spring 98 received'by mouth portion 96 'ofsuch shaft is turned, but as the opposite end of the spring is held against turning by opening 32 in 'adjustormember 24- such spring and the spring leaves 99 thereof are twisted to store energy therein.

.a simple and compact spring device for closing the breechblock of cannons which .does not occupy any space therein in addition to the designed configuration of the operating components and which is easily adjusted to any desired torsional movement.

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.

We claim:

1. In a cannon having a breech ring with a breechblock mounted therein for slidable movement between an open position and a closed position, a shaft mounted for rotatable movement in the breech ring, crank means mounted to said shaft for camming cooperation with the breechblock for actuation thereof between the open and close positions, an adjustor member mounted for rotatable movement in the breech ring, said adjustor member being axially aligned with said shaft and adjacent one end thereof, said shaft being provided with a bore introduced into the end thereof adjacent said adjustor member, said bore being terminated by a rectangular mouth portion, said adjustor member being provided with a rectangular opening similar to said mouth portion, a torsional spring of rectangular cross-section mounted in said bore with the ends thereof being received by said mouth portion and said opening, a drive pin mounted through said shaft and a mating circular hole through said spring for anchoring said spring to said shaft, a retaining pin mounted through said adjustor member and an elongated hole in said spring, said elongated hole providing for linear displacement of said spring when twisted, and a plunger resiliently mounted in said breech ring for cooperation with a stepped recess in said adjustor member to selectively position said adjuster member for adjustably preloading said spring to assure actuation of the breechblock thereby to the close position.

2. The combination as defined in claim 1 wherein said torsional spring comprises a plurality of stacked spring leaves.

3. The combination as defined in claim 1 with clearances provided in said mouth portion and said opening for the angular displacement of said spring leaves when twisted.

References Cited in the file of this patent UNITED STATES PATENTS 422,838 Rostel Mar. 4, 1890 72,462,920 Summerbell et a1. Mar. 1, 1949 2,491,539 Windham Dec. 20, 1949

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