Improvements in Breech-loading Ordnance.
Year: 1889

page_text: Date of Application, 16th Oct., 1889
Complete Specification Left, 25th June. 1890-Accepted, 26th July, 1890
PROVISIONAL SPECIFICATION.
Improvements in Breech-loading Ordnance.
I, JAMES ATKINSON LONGRIDGE, of Grève d'Azette, in the Island of Jersey, Civil
Engineer, do hereby declare the nature of this invention to be as follows:-
My Invention relates to the breech-closing mechanism of breech-loading
ordnance; and consists in improved means of securing and opening the breech piece
carrying the breech-closing plug or obturator.
The object and effect of my invention is first to diminish the external length of the
gun relatively to the internal effective length of the bore or what is the same thing
increase the latter relatively to the former to an extent almost equal to the length of
the screwed chamber in which the breech closer has heretofore usually been screwed;
secondly to obviate the use of a loading tray; thirdly. to distribute the rearward
longitudinal strain on the external jacket as uniformly as possible over the cross-
sectional area of the metal of which it is composed; and lastly to simplify the
construction and operation of the breech-opening and closing mechanisın.
My Invention consists in forming the breech piece which carries the breech plug
and obturator in the form of a cap which when the breech is closed covers the rear
end of the jacket and is held in place by screw threads on the exterior of the jacket
and the interior of the cap. These threads are cut away in alternate sections of the
circumference so that when a partial turn round its axis is given to the cap, the
threads upon it disengage from those on the jacket and the cap can be withdrawn.
These threads may be either spiral or parallel to each other in a plane at right angles
to the axis of the gun. The threads on the jacket are made decreasing in diameter as
they approach the rear of the gun and this decrease may either be continuous so that
the arrises of the threads are contained in the surface of a cone or a conoidal frustrum,
or they be in groups of two or more threads so as to form a series of steps decreasing
in diameter backwards. The cap is carried by a ring which is pivoted on a vertical
axis attached to the jacket, round which axis it may be swung when the locking threads
are disengaged by the partial rotation of the cap. In some cases, there is a movement
of translation in the direction of the axis of the gun between the rotating unlocking
movement and the swinging movement of the cap. In some cases, by a suitable
variation of the diameters of the threads, this longitudinal motion may be dispensed
with and the breech swung aside immediately after the rotation motion. These various
motions are effected by suitable combinations of levers, cog wheels, racks, and spiral
cams.
The cut away portions of the threads may be either in continuous lines on the
development of the surfaces of the threads, or they may alternate so that the cut away
portion of one thread or step of threads may be opposite the uncut portion of the
succeeding thread or step of threads, the effect of which arrangement is to ensure a
more equable distribution of the strain over the sectional area of the jacket. Instead
of the carrier ring being swung round on the pivot attached to the jacket, it may, by
a suitable arrangement, be made to move laterally at right angles to the axis of the
bore so as to uncover the breech end for loading. By placing the locking threads
outside the jacket, the obturator may be brought very near to the end of the gun,
thus lengthening the effective length of the bore and at the same time dispensing with
the use of a loading tray. In some cases, the shock of the explosion upon the threads
may be diminished by the introduction of an elastic cushion between the cap and the
plug which carries the obturator.
Dated this 16th day of October 1889.

page_text: COMPLETE SPECIFICATION.
Improvements in Breech-loading Ordnance.
I, JAMES ATKINSON LONGRIDGE of Grève d'Azette in the Island of Jersey, Civil
Engineer, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :--
My Invention relates to the construction of breech-loading ordnance and to the
mechanism for opening, closing, and securing, the breech-piece thereof and it has for
its object to increase the internal effective length of the bore relatively to the total
external length of the gun; to obviate the use of a loading-tray; to transmit the
rearward longitudinal strain on the breech plug directly to the external jacket and to
distribute said strains as uniformly as possible over the cross-sectional area of the
metal; and to simplify the construction and operation of the breech opening and
closing mechanism.
I will now describe the same by reference to the accompanying drawings shewing
the general principle of the invention. Figure 1 is a side elevation of the breech
end of a gun partly broken away. Figure 2 is a horizontal longitudinal section of
the same. Figure 3 is a transverse section of figure 1, looking towards the breech.
Figure 4 is a rear view of the breech closing cover shewing the gear for overcoming
the initial grip of the obturator in the bore. Figure 5 shews a horizontal longitudinal
section of the breech having a modified form of screw and opening mechanism, and
figure 6 is a development of part of the screw on the jacket, shewing how the segments
of thread and interruptions may break joint or alternate. Figure 7 is a longitudinal
section of the breech, shewing a safety-firing mechanisın. Figure 8 is a detail, on a
larger scale. Figures 9 and 10 are details of a modified form of safety firing
mechanism. The same letters of reference indicate like parts in all the figures.
In the usual system, known as that of the "Interrupted Screw," the breech is closed
by a block of steel carrying the obturator and having a series of threads upon its outer
surface which take into a corresponding series of female threads on the inner surface
of the body of the gun or jacket. These threads are cut away in alternate segments
so that when the block is rotated on its axis through an arc equal to one of these
segments the whole of the threads are liberated and the block may be drawn back in
the line of the axis of the gun, and then swung or moved aside so as to open the
breech end of the powder chamber. In such cases, it is generally found necessary to
make use of a loading tray so as to preserve the internal screw-threads from being
injured by the introduction of the charge and projectile.
According to my invention, the plug which carries the obturator is attached to, or
forms part of, a cap or cover which encloses the breech end of the body or jacket of
the gun and screws, or engages, on the exterior thereof. This mode of construction
is illustrated as applied to guns known as "wire guns." A is the cap or cover which
carries the obturator C that closes the breech end of the bore D of the gun. Bis the
jacket by which the longitudinal strain is transmitted from the breech to the trunnions
or, in large guns, to the saddle which replaces the trunnions. On the interior of the
cap A are cut a series of threads a, which may be either spiral, or parallel to a plane
perpendicular to the axis of the gun, and a corresponding series of threads 6 are cut
on the outside of the body or jacket B. Each of these series of threads is cut away
in alternate segments, as in the usual system of the "interrupted screw," and each
series of threads follows in general outline the figure of a frustrum of a cone so that
the threads diminish in diameter from the front to the rear in order that the cap A,
after being partially rotated to unlock the threads, may be at once swung aside round
a pivot E mounted at one side of the jacket B without being first drawn back in the
direction of the longitudinal axis of the gun, as in the ordinary internal screw-
system.
Thus it will be seen that only two movements are required for opening the breech
instead of three as usual. It will also be seen that as there are no internal screw

page_text: threads in rear of the powder chamber, to be protected, the projectile and charge may
be introduced without the use of a loading tray. Consequently, time is saved in
loading the gun and the effective length of the bore, relatively to the total length of
the gun, is increased to an extent almost equal to the length of the breech plug.
The series of threads a and b may be made to decrease in diameter either uniformly,
continuously in a curve, or by steps, each step containing two or more threads, but it
will be obvious that, in each case, the degree of conicity should be such that the
threads of the cover will clear the jacket when the former makes its angular motion
about the centre E. The interruptions of the threads may be either continuous in the
fore and aft direction, as usual in the case of the internal screw, or the interruptions
and threads may alternate or "break joint," as shewn in figure 6, but this is only
possible when thedegree of conicity is such that successive threads decrease indiameter
by steps not less than the depth of the thread, so that the segments of thread a', for
example, in figure 5, which engage with the segments of thread &, figure 6, will pass
clear over the tops of the segments of thread 6, figure 6, which are opposite the
interruptions between the threads b¹, and so on, the relations of the other series of
segments or threads 63 b being similar. By this means a more uniform distribution
of strain over the sectional area of the jacket is obtained than is the case where the
interruptions do not alternate with the threads.
I will now describe the arrangements which mayconveniently be adopted for operating
the opening of the breech,although, obviously, various other inechanical combinations
may be employed.
First as to quick-firing guns and guns of small calibre. Referring to figure 5, the
cap A is carried by a carrier ring F in which it is free to rotate round the axis of the
gun but is prevented from moving backwards or forwards by proper flanges or stops.
This ring has an arm which is hinge-jointed at E to a bracket firmly fixed to the
outside of the body or jacket of the gun. To the cap A is pivoted a lever G which
serves first to rotate the cap A through the necessary angle to liberate the threads and
then by a second motion at right angles to the first to swing back the cover A round
the axis E and open the breech. In case of any sticking or excessive friction at the
obturator C the pivoted end of the lever G has a cain g, which, when the lever G is
moved in the direction of the arrow, figure 5, acts upon a bolt g' sliding through the
cover A and bearing at its inner end against the rear end of the gun and serving as a
thrust pin to overcome the resistance due to binding of the obturator in the bore.
For heavy guns a similar arrangement may be adopted, but I prefer a modification
which I will now proceed to describe. Instead of the cover A being fitted to turn in the
carrier ring F and the latter in ounted on a fixed pivot E, as in figure 5,the ring F is
fitted to rotate on the jacket or body of the gun, as shewn in figures 1,2, and 3, and
the ring F carries the pivot E upon which the cover A swings for opening and closing
the breech, the ring F and cover A rotating together for locking and unlocking the
threads. The rotation of the ring F and cover A is limited by stops and is effected
by a worn on a shaft mounted in a bracket carried by the jacket or body of the
gun and actuated by the hand-wheel H the worm gearing into a toothed segmenth'
on the carrier ring F. The ring Falso carries a horizontal axis furnished with a
worin i and a hand-wheel I. The worm i gears with a toothed seginent i¹ formed
around that knuckle of the joint to which the cover A is fixed, so that by operating
the hand-wheel I the cover A is swung around the axis E to open or close the breech.
To overcome the friction of the obturator in its first movement from its seat, the
arrangement shewn in figures 1, 2, and 4, may be used. k are three thrust pins fitted
to slide through, but not to rotate in, the cover A. The rear ends of these rods are
screw-threaded and pinion nuts K work upon them, the three pinion nuts gearing with
the same toothed ring L which is fitted to rotate about the inner flange of an annular
casing M enclosing the gear. This ring L is operated by a worm n on a shaft provided
with a hand wheel N by turning which the pinion nuts K, which take a bearing
gainst the casing M,force the thrust rodsksimultaneously against the bodyof the gun
and thus the friction or grip of the obturator is overcome. By properly proportioning
he ratio of ring L to the different pinions K according to their distance from the

page_text: axis E, or by properly varying their pitch, the angular motion of the cover may be
compensated so that an equal pressure of the thrust rods against the gun is obtained.
In some cases it may be more convenient to place the pinion nuts inside of the ring L
which, in that case, would have teeth cut on its inner circumference and also on its
outer face for the worin n to gear with.
There are thus three operating hand wheels, as shewn in figure 1. By H the
cover A and ring Fare rotated so as to unlock the threads of the "interrupted screw;
by N the friction or grip of the obturator is overcome; and by I the cover A is
swung aside. In closing and locking the breech the hand wheels would be turned in
the reverse direction, in the order N, I, H.
Although in the drawings and description a wire built gun is represented, it is
obvious that the same arrangement may be applied to a built-up gun or to a solid gun
of the ordinary kind. The firing apparatus inay be of the ordinary kind, either
percussive or electric, but I prefer the arrangement which I proceed to describe.
For quick firing guns I make use of a metallic cartridge fitted with an explosive
capsule in the ordinary manner.
In figure 7 o is a steel pin provided with a cap o' which fits over a seat or boss
formed in the centre of the inner face of the obturator plug C. The pin o passes
through into a chamber in the obturator closed at the outer end by a nut and in which
works a spring-actuated striker p, the spring being confined between a disc on the
inner end of the striker pin p and the nut through which the pin p passes. When
the strikerp is drawn back, the spring is compressed and when the striker is
released it is driven forward by the spring and the blow is transmitted through pin o
to the capsule of the cartridge which it explodes, all escape of gas through the
obturator plug being prevented by the cap o'acting as a gas check. The strikerpwhen
drawn back is retained in the cocked or firing position by a spring detent q from which
it is released by means of a lanyard.
The cocking of the striker p is effected by the act of turning the cover A to unlock
the threads by which it is secured, the cocking being effected through the agency of
a lever pivoted to A and engaging at one end with pin p and connected at the other
end by a rod s passing through cover A to a latch levert pivoted on the inside of
cover A and having a bevelled nose that its other end which, when the cover A is
turned for the purpose of opening the breech, rides up the bevelled end of a rib u on
the body of the gun. When, after loading the gun, the cover A is rotated in the
opposite direction so that the threads of the "interrupted screw" are fully locked, the
nose t¹ comes opposite a gap v,shewn more clearly in figure 10, into which the nose t¹-
is free to fall when the lanyard is pulled to release the striker from the detent. Ifthe
striker should be accidentally released before the breech cover is partially closed no
harm can be done, because the transmitter o will not then be within reach of the
capsule of the cartridge, and when the cover A is closed but not completely locked,
the nose bears against the rib u which holds the striker forcibly retracted so that
the gun cannot be fired until by the rotation of the cover A the nose t' is brought
opposite the recess v. Thus it is impossible to fire the gun until the breech is safely
locked whilst, on the other hand, by the very act of unlocking the breech the gun is
cocked ready for the next firing. Instead of the bevelled end t' riding upon a pro-
jecting rib w, as shewn, a recess may be cut in the end of the jacket B which recess
is immediately opposite the bevelled end t when the parts are in the firing position so
that the end will fall into said recess when the gun is fired. This recess has a
bevelled side up which the bevelled part of t¹ rides when the cover A is revolved to
unlock the threads, thereby cocking the hammer.
A modification of this safety-firing device, adapted to large guns, is shewn in
figure 9 which shews the parts in the position they occupy after firing. w is a cavity
for the ordinary percussive primer, for which may be substituted, when desired, the
electric primer. R is the haminer pivoted and connected to the lever t in the same
way as the lever before described. The hammer R has a horn q¹ which engages with
the spring detent q when the hammer is cocked. The haminer R is actuated by a
spring engaging with a slot at the under side of the hammer. This spring may be

page_text: in one with the detent 7. As in the former case, it is impossible to fire the gun until
the breech is closed and locked so that the nose t¹ is in alignment with the recess v.
In figure 9 the obturator is similar to that well known as the De Bange system.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is;
1. In the construction of breech-loading ordnance, securing the breech-closing
obturator in position by a cover screwing or otherwise engaging on the exterior of the
jacket or body of the gun, as specified, whereby the effective length of the bore is
increased, as described.
2. In the construction of breech-loading ordnance, securing the breech-closing
obturator in position by a cover screwing or otherwise, engaging on the exterior of the
jacket or body of the gun, the threaded or engaging parts of the cover and jacket or
body being approximately conical or of progressively diminishing diameter towards
the rear so as to distribute the strains through the metal of the jacket or body and
enable the disengagement of the cover to be effected by an angular motion only, about
a centre, as described.
3. In the construction of breech-loading ordnance, securing the breech-closing
obturator in position by a cover screwing or otherwise engaging on the exterior of the
jacket or body of the gun, the threaded or engaging parts of the cover and jacket or body
being approximately conical or of progressively-diminishing diameter towards the rear,
the threads and their interruptions breaking joint or alternating as described in
reference to figures 5 and 6 and for the purpose described.
4. The combination, with the cover screwing on the exterior of the gun as described,
of one or more thrust rods passing through the cover and bearing against the gun for
overcoming the grip of the obturator in the bore, the thrust rod or rods being operated
by a cam or screw-motion as described.
Dated this with dor of Tune 1800