Improvements in Breech Mechanism for Guns.
Year: 1888

page_text: Date of Application, 17th Apr., 1888
Complete Specification Left, 11th Jan., 1889
Complete Specification Accepted, 2nd Mar., 1889
Improvements in Breech Mechanism for Guns.
I, THORSTEN NORDENFELT, of 53 Parliament Street, in the City of Westminster,
Civil Engineer, do hereby declare the nature of this invention to be as follows:-
My improvements relate to breech mechanism. for guns formed as described in
previous applications for Patents made by me in such manner that a screw breech
block formed with divided segments of screw threads, has first given to it a turning
movement to unlock it is then drawn back and is afterwards carried away to one
side by one turning movement of a lever handle-I now give these movements to the
screw breech block by a lever handle secured directly to the screw block itself.
I make the rear end of the screw block to extend backwards from the breech end
of the gun into a ring which I call a carrier ring and which at one side near its
lower part can be turned around a pin which projects backwards from the rear end of
the breech of the gun.
The carrier ring I form with a pin projecting inwards from it and entering a
groove formed in the circumference of the breech block. This groove at its rear
end first passes for a distance around the block in a direction inclined to its axis to
the same extent as the screw threads which are upon it--and then passes along and
partly around the block in a long open helicoidal curve. The segments of the screw
threads upon the block I also make to wind partly around the block in the same heli-
coidal curve in place of making them straight and parallel with the axis of the block
as has heretofore always been the case in breech mechanism having divided segments
of screw threads.
With this construction, when to open the breech the screw breech block is turneu
by the lever handle which extends from it-it first screws itself back until the
segments of screw threads upon it are disengaged from the segments of screw threads
upon the gun-When this takes place the end of the quick threaded portion of the
groove in the block comes against the pin on the ring and as the block continues to

page_text: be turned by the lever handle it is at the same time drawn backwards until the end
of the groove comes against the pin the carrier ring carrying the screw breech block
within it is then turned for a distance around the pin by which it is pivotted to the
breech of the gun and is so carried away to one side leaving the breech open.
Dated this 17th day of April 1888.
COMPLETE SPECIFICATION.
Improvements in Breech Mechanism for Guns.
I, THORSTEN NORDENFELT of 53 Parliament Street, in the City of Westminster,
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 improvements relate especially to breech mechanism for guns formed as
described in previous applications for Patents made by me No. 17351 in the year 1887
and No. 2604 in the present year in such manner that a screw breech block formed
with divided segments of screw threads, has first given to it a turning movement to
unlock it is then drawn back and is afterwards carried away to one side by one
turning movement of a lever handle.
I now give these movements to the screw breech block by a lever handle secured
directly to the screw block itself.
I make the rear end of the screw block to extend backwards from the breech end of
the gun into a ring which I call a carrier ring and which at one side near its lower
part can be turned around a pin which projects backwards from the rear ond of the
breech of the gun.
The carrier ring I form with a pin projecting inwards from it and entering a groove
formed in the circumference of the breech block. This groove at its rear end first
passes for a distance around the block in a direction inclined to its axis to the same
extent as the screw threads which are upon it-and then passes along and partly
around the block in a long open helicoidal curve. The segments of the screw threads
upon the block I also make to wind partly around the block in the same helicoidal
curve in place of making them straight and parallel with the axis of the block as
has heretofore always been the case in breech mechanism having divided segments of
screw threads.
With this construction, when the screw breech block is turned by the lever handle
which extends from it to open the breech-it first screws itself back until the segments

page_text: of scrow threads upon it are disengaged from. the segments of screw threads upon
the gun. When this takes place the end of the quick threaded portion of the
groove in the block comes against the pin on the ring and as the block continues
to be turned by the lever handle it is at the same time drawn backwards until the
end of the groove comes against the pin the carrier ring carrying the screw breech
block within it is then turned for a distance around the pin by which it is pivotted
to the breech of the gun and is so carried away to one side leaving the breech
open.
The screw breech blocks of other constructions of breech loading guns may
similarly be formed with the screw segments winding around in place of being
straight along them as heretofore so as on the firing of the gun to more effectually
distribute the backward strain over the whole of the metal forming the breech end
of the gun.
The drawings annexed show various views of the breech end of a gun formed as
above described.
Figure 1 is a rear end view with the breech closed. Figure 2 a longitudinal section
of the same taken on the line A B Figure 1-and Figure 3 is a rear end view with
the breech open.
A is the screw breech block with the segments of screw threads winding partly
around it-B the rear end of the gun with corresponding screw segments formed
in it.
C is a ring into which the rear end of the block A projects. D is a pin projecting
back from the rear end of the gun upon which a short arm C projecting from the
ring C can swivel. E is a lever handle jointed to the rear end of the block A. F is
a groove cut partly in the portion of the block A which projects from the rear end of
the gun and partly along one of the spaces between the spiral segments of screw
threads upon it.
G is a pin projecting inwards from the ring C and entering the groove F. As
above stated the rear end of the groove F passes for a distance around the block in a
direction inclined to its axis to the same extent as the screw threads of the screw
segments upon it and then passes along and partly around the block in a curve
corresponding to the curve of the side edges of these segments.
His a stop projecting backwards from the rear end of the gun-when the breech
block is being turned and consequently drawn back the side of the forward end of the
block bears against it when the forward end of the block has been drawn back clear
of the breech end of the gun and prevents this block and the ring C from being then
turned around the pin G until the backward movement of the block is completed the
end of the block is then clear of the stop and the ring carrying the block within it
can be turned into the position shown in Figure 3. A projection I from the front
face of the ring C then comes against a stop which projects from the rear end of the
gun and the ring is thereby prevented from turning further.
With breech mechanism constructed in the manner above described any suitable
mechanism may be used for drawing back the empty cartridge case when the breech
is being opened and for firing the cartridge when the breech is closed.
In the construction shewn in the drawing the withdrawal of the empty cartridge
cases is effected by two extractor claws which as described in the Specification of my
former Patents before mentioned are carried by slides K which are capable of being
drawn back along slots L formed in the gun and the slides have screw threads on
them for the screw threads on the block A to engage with.
When the block is turned to unlock it the screw threads on the block engage with
the threads on the slide and slowly draw it back and slightly withdraw the cartridge
case then when the block is drawn back as the screw threads are still engaging with
one another the extractor drawn back with it and completes the withdrawal of
the cartridge case-the extractor slides being then withdrawn into slots L' in the
ring C.
The arrangement shewn for firing the gun is as follows:-
A cavity is formed centrally through the breech block A-into this cavity is

page_text: inserted a cylinder M which carries within. it. the trigger and firing pin. The
cylinder Mis held in the cavity by projections upon.it, entering L shaped grooves cut
in the side of the cavity. When the cylinder is pushed endwise into the cavity the
projections upon it enter the parts of the grooves which are formed lengthwise of
the cavity and then when the cylinder has been fully inserted a partial turn is.
given to it thereby bringing the projections into the parts of the grooves which
are at right angles to the cavity and locking the cylinder to prevent its with-
drawal.
Within the cylinder is the rear end of the firing pin N and the spring O by
which the firing pin is to be thrown forwards. The forward end of the firing pin
has an arm N₁ projecting from it which enters a recess N³ formed at the side of
the cavity in the breech block.
At the time when the breech block is turned to unlock it the cylinder M is
held fast and prevented from turning with it as hereinafter explained and an
inclined side of the recess comes against the arm N¹ and forcing it back compresses
the spring O. The firing pin is itself prevented from turning within the cylinder
by an arm N2 on its rear end sliding in a slot in the interior of the cylinder.
As the firing pin is forced backwards is rear end bears against the forward
end of the trigger piece P and presses it back against the action of the spring Q
which presses it forwards. As the trigger is pressed backwards it has simultaneously
a partial turn given to it by reason of the end of a pin R carried by the cylinder
entering a spiral groove. S cut in its side.
When the firing pin has been pressed back to such an extent that the arm N²
on its rear end has passed out from the slot in which it was previously sliding the
firing pin has a partial turn given to it to bring the arin behind the abutment
through which the slot is cut and the hammer is thereby locked and held back-
just before the firing pin has this partial turn given to it a radial slot in the front
end of the trigger piece has by the turning of the trigger been brought into a line
with the arm N2 on the firing pin and when the firing pin is turned to bring it into
its locked position the trigger is thrown forwards by its spring and the arm N passes
into the radial slot in its forward end.
When the breech of the gun has been closed and the gun is to be fired the trigger
is drawn back by the cord T the firing pin is thereby turned in a direction to carry its
arm N2 clear of the abutment against which it was resting and when clear the firing
pin is thrown forward by the action of the spring O.
The locking of the cylinder M to prevent it turning with the breech block at the
time when the breech block is being turned to unlock it is effected in the following
manner.
The rear end of the cylinder M has upon it a plate M' which lies in a recess in
the rear end of the breech block A and carries a spring bolt V. When the breech of
the gun is closed a projection V on this bolt enters a notch in the ring C and thereby
locks the cylinder to the ring and prevents it from turning. When the breech
block A is turned to unlock it and is thereby drawn back a short distance the bolt
being carried back with it its projection V is withdrawn from the notch in the ring
just as the unlocking of the breech block is completed. At the same time the
turning motion of the breech block brings a notch in its rear end opposite to the
forward end of the bolt and the bolt is pressed forward by its spring into the notch
thereby locking the cylinder M to the breech block so that it turns with it and when
the breech is being closed is always brought back into proper position for the pro-
jection V of the bolt to enter just as the block has completed its quick forward
movement and is about to be turned to lock it in the gun-M is a handle fixed on the
plate M¹.
W is a plate carried by the boss of the arm C¹ of the ring C-this plate when the
drawing back of the breech block is completed and the ring is being turned around
the pin D comes in front of the rim of the cartridge case which has been withdrawn
from the barrel and prevents the case from being in any way forced forwards into the
barrel. The plate also serves as a stop for the rim of a cartridge which is being

page_text: inserted into the gun to come against and stop it in such a position that the claws of
the extractors may come in front of this rim when the ring Cand breech block are
turned around the pin D as the breech is being closed.
As before stated the breech block with the spirally formed screw threaded segments
upon it can not only be used as above described in conjunction with a carrier ring
which when the block has been withdrawn from the gun is capable of being turned
around a pin which projects backwards from the gun but can also be used with other
mechanism for carrying it away to one side after it has been withdrawn. For example
it may be used together with a carrier ring which in place of turning on a pin which
projects back from the rear end of the gun is capable of being turned aside around a
pin which is at right angles to the bore of the gun.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. A gun closed at the breech by a breech block having divided segments of screw
threads upon it which segments wind somewhat around the block in place of passing
straight along it as heretofore.
2. The combination of the breech block having segments of screw threads winding
partly around it, the lever handle by which it can be turned-the groove in the block
formed at one end parallel with the screw threads and at the other parallel with the
edges of the segments the carrier ring and the pin projecting inwards from it and
entering the groove in the block substantially as described.
3. The construction of the breech mechanism of breech loading guns substantially
in the manner hereinbefore described and illustrated by the drawings annexed.
Dated this 27th day of December 1888.
TH. NORDENDELT.