BREECH FOR A GUN WHICH IS ABLE TO OPERATE WITH TWO DIFFERENT BREECH BLOCKS

The invention relates to a first and second interchangable sliding block for the breech of a cannon.

Two types of ammunition are generally available for cannons: a first type known as cased ammunition in which the case carries the propellant charge, and a second type known as caseless ammunition which does not have such a case and for which the propellant charge has to be loaded separately into the firing chamber of the cannon.

The breech of the conventional cannon is adapted to handle only one of the aforesaid types of ammunition and different cannons are accordingly employed for shooting cased and caseless ammunition.

The conventional cannon breech usually includes a sliding block which is slidably movable in a transverse direction relative to the longitudinal axis of the firing chamber of the cannon from one position (hereafter referred to as the operative position) where it serves to seal off the rear end of the firing chamber of the cannon when the cannon is in the firing position, to a second position (hereafter referred to as inoperative position) where it does not seal off the said rear end.

Where the cannon of the type which fires cased ammunition, the said sliding block serves to support the rear end of an ammunition case loaded into the firing chamber of the cannon and to effect the aforesaid sealing off action in cooperation with such rear end.

One such arrangement is for example disclosed in DE-C-41,695 issued to Nordenfelt Guns and Ammunition Company Limited in 1887. In this arrangement the gun has a pivotally breech block which cooperates with the rear end of cased ammunition located in the firing chamber to seal the latter off. The arrangement also includes a lever for ejecting the case of the spent ammunition.

Where the cannon is of the type which employs caseless ammunition, an additional sealing means has to be employed for sealing off the rear end of the firing chamber.

One such an arrangement is, for example, disclosed in GB-A-15,309 issued to Eugene Schneider in 1911. In this arrangement the gun includes a breech block which is slidably or rotatably movable and which cooperates with a pivotally mounted obturator for sealing off the rear end of the firing chamber when the gun is in the firing position.

It will be appreciated that because the breech of the conventional cannon is adapted only to fire one of the aforesaid two types of ammunition, it restricts the usefulness of such a cannon. It is accordingly an object of this invention to provide an arrangement with which this problem can be overcome or at least minimised.

According to the invention a first and a second interchangable sliding block are provided for the breech of a cannon which has a firing chamber with a bored rear end into which ammunition of either the cased or caseless type can be loaded; each sliding block being movable from an operative position whore it seals off the said rear end of the firing chamber when the cannon is in the firing position, to an inoperative position where it does not seal off the said rear end the said first sliding block being intended to be used when the cannon has to fire cased ammunition which has a rear end which is located at the said rear end of the firing chamber when the cannon is in the firing position, the said first sliding block also being capable of supporting and cooperating with said rear end of the cased ammunition in the firing chamber in order to seal off the said rear end of the firing chamber; and the said second sliding block, which in intended to be used when the cannon has to fire caseless ammunition, being capable in the said operative position to trap a sealing member In sealing engagement with the bore of said rear end of the firing chamber when the cannon is in the firing position.

It will be appreciated that a cannon with such a breech will be able to fire both cased and uncased ammunition simply by employing the appropriate sliding block in the breech of the cannon.

Further according to the invention the sealing member includes a substantially semi-ball shaped plug which can fit removably into the rear end of the bore of the firing chamber, the plug including over its outer circumference sealing means for releasably engaging the inside rim of the said bore.

Preferably the sealing means comprises a so called De Bange obturation system.

Further according to the invention the sealing member includes a centrally located axially extending hole which communicates with the inside of the firing chamber when the plug is located in its bore, the said hole providing a path or flash channel through which a propellant charge located in the firing chamber can be ignited.

Still further according to the invention the sealing member is connected to one end of an elongated lever of which the other end is pivotally connected to the cannon breech ring.

With this arrangement the sealing member can be swung pivotally from one or operative position where the plug is located in the bore of the firing chamber, to a second or inoperative position where it is located outside the breech of the cannon.

It will be appreciated that such an arrangement provides for an increase in the firing rate of such a cannon to a level comparable with that of a conventional cannon intended for firing caseless ammunition.

Preferably the said free end of the lever is mounted on a transversely extending shaft of which the ends are rotatably mounted on or in the breech ring of the cannon.

The invention also includes within its scope a method of converting an existing conventional cannon which is either of the type capable of firing cased ammunition only, or of the type capable of firing caseless ammunition only, to one capable of firing both types in the manner set out above, as well as to a cannon which has been so modified.

It will be appreciated that because of the relatively simple modifications which are required, the arrangement lends itself to a very rapid conversion of such a conventional cannon to a cannon according to the invention.

The invention will now be described further by way of example with reference to the enclosed drawings in which:

Figure 1

is a diagrammatic longitudinal section through the breech and associated parts of a conventional cannon adapted for firing cased ammunition only, the sliding block of the breech being shown in the operative position;

Figure 2

is a similar view as that of figure 1 of one embodiment of a breech according to the invention, shown in the operative position;

Figure 3

is a similar view as that of figure 2, with the breech shown in the in-operative position; and

Figure 4

is a diagrammatic perspective view of the breech of figure 3.

Referring to all the drawings, the breech 10 of a cannon comprises a breech ring 11 which defines a trough like elongated channel 12 of which the one end communicates with the rear end of the bore of the firing chamber 13 of a cannon of which the rest of the details are not shown.

In the arrangement shown in figure 1, breech 10 is that of a cannon intended to fire cased ammunition 14 only. Such ammunition can be loaded via channel 12 of breech ring 11 into firing chamber 13 so that the rear end 15 of the case 16 of ammunition 14 engages the surrounds of the bore of chamber 13 from where it can be extracted by the lug 17 of an extractor 18 after a shot had been fired.

Breech mechanism 10 of the embodiment of figure 1 includes a conventional type sliding block 19 which is reciprocally slidable in the direction of arrow 20, i.e. transversely relative to the longitudinal axis of chamber 13, from a first or operative position shown in figure 1, to a second or inoperative position similar to that shown in figures 3 and 4 for a sliding block 21.

When block 19 is in the operative position shown in figure 1, its leading end frictionally engages the rear end 15 of case 16 to support it and to cooperate with it to seal off the rear end of the bore of chamber 13 while the cannon is in the firing position.

When the shot had been fired, block 19 slides to its inoperative position and at the same time case 16 of the spent ammunition is ejected by the lug 17 of extractor 18 from chamber 13 via breech ring 11.

The cannon can then be reloaded in conventional manner.

In the arrangement shown in figures 2 to 4, in which some of the details of lug 17 and extractor 18 have been omitted for clarity purposes, a modified block 21 is provided which, similar to block 19, is reciprocally movable in the direction of arrow 22 between its operative position, shown in figure 2, and its inoperative position shown in figures 3 and 4.

In this arrangement, which is intended for utilisation in a cannon which can fire both cased and caseless ammunition, sliding block 21 is of such width that when it is in its aforesaid operative position (figure 2) it can trap a sealing member 23 in the mouth of the rear end of the bore of firing chamber 13 to seal the latter off while the cannon is in the firing position.

Sealing member 23 comprises a substantial semi-ball shaped plug 24 which can pass into the bore of chamber 13 and which is provided over its outer circumference with a sealing system 25 of the so called De Bange obturation - type which can sealingly engage the inside rim of the mouth of the bore of chamber 13.

Plug 24 is connected to one end of an elongated lever 26 of which the other end is connected to a shaft 27 of which the ends are rotatably contained between two spaced apart protrusions 28 mounted on the upper face of breech ring 11. It will be appreciated that in an alternative arrangement the ends of shaft 27 may be contained rotatably within breech ring 11.

Sealing member 23 is hence pivotally movable from a first or operative position shown in figure 2, where it seals off the mouth of the bore of chamber 13 when the cannon is in the firing position, to a second or inoperative position, shown in figures 3 and 4, where it is located outside breech ring 11 when the cannon is not in the firing position.

Sealing member 23 includes a centrally located passage 29 which serves as the flash channel through which the propellant charge located inside chamber 13 can be ignited when the cannon is fired.

It will hence be appreciated that when the cannon of figures 2 to 4 is intended to fire cased ammunition 14, sliding block 19 is employed with sealing member 23 being pivoted to its inoperative position.

When the cannon has to fire caseless ammunition, block 21 and sealing member 23 are utilised in the manner described above. Because of the simplicity of operation of such a sealing member 23, the firing rate of a cannon utilising it is more rapid than that of the conventional type of cannon intended for firing caseless ammunition.

It will be appreciated that apart from including such a dual purpose breech system on newly manufactured cannons, existing cannons may also be modified to incorporate such sliding blocks 19 and 21 and sealing member 23. For this purpose such sliding blocks 19 and 21 and sealing member 23 may be supplied as a loose kit. It is also intended for the scope of this invention to extend to such a kit. Because of the ease and simplicity with which such a kit can be fitted to an existing cannon of the cased or caseless type, the conversion can be effected very rapidly.