Improvements in the Breech Mechanism of Ordnance.
Year: 1898

page_text: Improvements in the Breech Mechanism of Ordnance.
We, LOUIS SILVERMAN, Engineer, and Lieutenant ARTHUR TREVOR DAWSON, late
of the Royal Navy, both of 28, Victoria Street, in the County of London, do
hereby declare the nature of this invention to be as follows:-
Our invention relates to conical or taper breech blocks or plugs having con-
tinuous or uninterrupted screw threads' thereon.
The chief object of our invention is to so form the aforesaid screw threads that in
order to unlock the breech block, or disengage its threads from those in the breech
chamber of the gun, it shall not be necessary to give said block more than a single
révolution.
1!
For this purpose we propose to form the aforesaid screw threads in such a
manner that in cross section one side or face of each thread lies at an angle of
approximately 45° and the other side or face at an angle of approximately 30° to
an imaginary line extending through the apex of the thread and parallel with the
ends of the breech plug. One side of the thread is longer than the other, the
shorter side acting to support the block against endwise thrust.
By this mean's we not only provide for a very firm support for the breech block
or plug so that it will effectually resist the internal pressure of the gun when the
latter is fired but we also provide for the ready disengagement of the said breech
block by a single revolution thereof.
We may employ any suitable means for revolving the said block and causing it
to be withdrawn from the breech of the gun, and if desired we may provide suitable
gear so that a partial revolution given to an appropriate handle will completely
unlock the breech plug.
.
We wish it to be understood that we do not confine ourselves to the precise
construction of the screw threads above described.
Dated this 19th der of Tonuow
1.000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.
We, LOUIS SILVERMAN, Engineer, and Lieutenant ARTHUR TREVOR DAWSON,
late of the Royal Navy, both of 28, Victoria Street, in the County of London, do
hereby declare the nature of this invention and in what manner the same is to
[Price 8d.]

page_text: be performed, to be particularly described and ascertained in and by the following
statement:-
Our invention relates to guns having a conical or taper breech provided with
continuous or uninterrupted screw threads.
The chief object of our invention is to so form the aforesaid screw threads that,
in order to unlock the breech block or disengage its threads from those in the
breech chamber of the gun, it shall not be necessary to give said block more than a
single revolution about its axis.
Any suitable means may be employed for revolving the said block and causing
it to be withdrawn from the breech of the gun, although we prefer to employ the
means hereinafter described.
In order that our said invention may be clearly understood and readily carried
into effect we will proceed to fully describe the same with reference to the
accompanying drawings in which:
-:
Figure 1 is a diagrammatic view illustrating the shape of the screw threads
with which the breech block and the gun are formed.
Figure 2 is an end elevation and Figure 3 a horizontal section on the line 1, 1,
of Figure 2, shewing the breech end of the gun with our improved breech-block
and the mechanism for operating the same.
Figures 4 and 5 are similar views shewing a modification of the breech
mechanism.
A is the breech-block; B the gun; and C the swinging carrier in which the
block is mounted and by which it is withdrawn from the breech after being dis-
engaged from the screw threads therein.
Referring first to Figure 1 it will be observed that the screw threads are so
formed that one side or face a of each thread lies at an angle of approximately 45°
and the other side or face a at an angle of approximately 30° to an imaginary
line a extending through the apex of the thread and at right angles to the
longitudinal axis of the breech plug. The side a of the thread is longer than the
other side a¹ which acts to support the block against endwise thrust.
By this means we not only provide for a very firm support for the breech block
so that it will effectually resist the internal pressure of the gun when the latter
is fired but we also provide for the ready disengagement of the said breech block
by less than a single revolution thereof.
Referring now to Figures 2 and 3, the breech-block is provided with a neck A¹
which is screw threaded to engage with corresponding screw threads formed in a
hollow boss C of the carrier. The said neck passes through a sprocket wheel c
which is provided with a feather d engaging with a longitudinal groove A* in the
said neck. This sprocket wheel is connected with the carrier by keys c passing
through a circumferential groove in the sprocket wheel, so that the latter is
capable of revolving with the neck A' without sliding thereon. ² is a driving
chain connecting the sprocket wheel c with another sprocket wheel mounted
on a short axle fixed to the carrier. The said sprocket wheel c³ has a worm
pinion gearing with a worm c6 mounted on a vertical shaft c which constitutes
the hinge pin about the axis of which the carrier swings in its opening and closing
movements. The shaft is provided with a bevel wheel gearing with a bevel
pinion on a shaft co which is furnished with a hand-wheel c¹ for enabling the
mechanism to be operated. When this hand-wheel is revolved to open the breech
it imparts motion to the sprocket-wheel c through the intervention of the bevel
wheels, the worm and pinion 56 and the chain and sprocket wheel c³ ³,
whereby the block A is caused to perform somewhat less than a single revolution
to disengage its screw threads from those of the breech. Further rotation of the
breech block in the same direction is prevented by reason of the end of its neck A¹
reaching the end of the cavity in the boss C' and therefore the continued rotation
of the hand wheel ceases to turn said block but causes the carrier to be swung
open as is well understood.
In order to prevent the breech block from being turned when the carrier is

page_text: open, a spring pin D is provided, which, as the carrier swings open protrudes from
the carrier under the action of its spring and engages with a recess in the block
thereby retaining said block locked until the carrier is closed again by the revolu-
tion of the hand-wheel c¹ in the opposite direction. As the carrier terminates
its closing movement the said pin by striking against the gun leaves the afore-
said recess and releases the block. The continued revolution of the hand wheel
therefore causes the block to be turned in a direction to bring its screw threads
again into engagement with the threads in the gun and to thereby close the
breech.
In the modification illustrated in Figures 4 and 5 the screw threaded neck A¹ of
the breech block extends through the screw threaded boss C¹ and has fixed to its
outer end a sleeve 02 which surrounds the said boss and is furnished with a crank
handle C. This handle is provided with a spring controlled locking lever C
having a tooth C to engage with a cavity C in the carrier when the breech is
fully closed. In this construction the opening and closing movements of the
carrier are effected without special gearing, by the operator's simply pulling or
pushing the said handle C³ according as it is desired to open or close the carrier.
The breech-block is, in the construction illustrated, provided with a firing pin E
which is made hollow for the reception of a spiral spring e and is furnished with a
lateral projection or finger pieco el which protrudes through slotted openings
in the neck A¹ and the sleeve C². The outer end A2 of the boss C¹ is formed with
a spiral cam surface and the said projection or finger piece e¹ travels on this cam
surface when the handle C3 is turned in a direction to rotate and disengage the
breech block. Consequently the unscrewing movement of the block causes the firing
pin to be cocked, in which position it is retained by a sear F carried by the
block. For the purpose of releasing the sear when the breech has been fully
closed, a rocking shaft G is provided on the carrier, one end of said shaft having a
finger g and the other end an arm g¹. The finger g lies adjacent to the bent end f
of the aforesaid sear so that when the arm g¹ is actuated by a lanyard or otherwise,
the said finger will trip the sear, thereby releasing the firing pin which
consequently strikes and explodes the detonator of the cartridge in the gun.
When the carrier is swung outwardly to open the breech, a protuberance C7
thereon strikes against a shoulder ½ on an extractor H and by turning such
extractor about its pivot h¹ extracts the empty cartridge case from the gun in the
well known manner.
In order to prevent the breech block from turning when the carrier is open, we
provide said carrier with a spring pin D' which acts in an analogous manner to
the spring pin D in Figures 2 and 3.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is;-
1. A gun with a conical breech which when closed is secured by screw threads
having the form or configuration herein described.
2. The conical breech block having the peculiarly formed screw threads in
combination with the mechanism herein before described with reference to the
accompanying drawings.
Dated 1041 dan of Ostahan 1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.