Improvements in Breech Mechanism for Ordnance.
Year: 1896

page_text: Date of Application, 28th July, 1896-Accepted, 3rd Oct., 1896
COMPLETE SPECIFICATION.
Improvements in Breech Mechanism for Ordnance.
I, ARENT SILFVERSPARRE, of Bofors, in the County of Wermland, in the Kingdom
of Sweden, Mechanical 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 :-
The object of the present invention is to so arrange the breech mechanism of
guns provided with a breech screw of ogival or conical shape that the gas check
known by the term "de Banges" will be applicable to such guns. As is well
known, this gas check consists of an elastic disk located at the inner side of the
breech block between two dished plates, the outer circumference of said disk being
pressed outward against the walls of the gun when the breech block is forced
backward at the firing of the gun.
In the accompanying drawings I have shown a breech mechanism arranged in
accordance with my invention.
Figure 1 represents a rear view and
Figure 2 a longitudinal section of the mechanism in its closed position;
Figure 3 is a longitudinal section, showing the breech screw rotated and extracted
until the gas check has left its closing position, and
Figure 4 represents a longitudinal section of the breech mechanism swung clear
over to the side.
The ogival or conical breech screw 1, which, in the usual manner, is provided
at its circumference with threaded segments, is made to turn on a hollow gudgeon
projecting from the lever or carrier 4, which is hinged on a spindle 7 attached to
a sliding carriage 24, arranged at one side of the rear end of the gun and being
movable on the guide 25.
On the spindle 7 there is also a roller 6 and a worm wheel 8 which by means
of the worm 9 and the toothed gears 10 is connected to a hand wheel 11 located
at the rear end of the gun, the roller thus being rotated on turning the hand-
wheel. In the roller 6 there is a helical groove 22 extending over a portion of
the circumference of the roller and having less inclination at the inner than at the
outer end. This groove embraces loosely one end 21 of a two-armed lever 5
fulcrumed on the inner side of the lever or carrier 4 the outer end of said lever
being made in the shape of a toothed segment engaging with corresponding teeth
in the circumference of the breech screw. When the roller is turned, the groove 22
will cause the lever 5 to rotate the breech screw on its gudgeon through an angle
corresponding to the width of the threaded portion, this rotation, owing to the
peculiar shape of the groove 22, at first taking place slowly, though with great
power, and afterwards with increasing velocity.
Further, the roller is provided at its circumference with a bevel lug or
projection 33 which during the rotation is brought up against the guide 25 thus
preventing further motion of the roller.
The motion of the sliding carriage is limited by means of the stop screw (or lug) 26
which slides in a slot 27 in the guide. In the rear end of the breech screw there
is a safety catch 12 movable radially and acted upon by a spring 13, said safety
catch, when the mechanism is completely closed, entering a recess 23 in the rear
end of the gun thus preventing the rotation of the breech screw. The safety catch
is provided at the inside with a lug 14 which, when the mechanism is closed, will
rest in the outer end of a radial prolongation of a groove 15 in the lever or
carrier 4 concentric to the breech-screw, but, when the catch is pulled inward, will
rest in the curved part of the groove thereby keeping the catch out of engagement

page_text: with the gun and allowing of turning the breech screw. At the other end of the
groove just mentioned there is another similar prolongation 16, and in the same
radial line as the latter an incline 17 is formed in the rear end of the gun..
When the breech screw is extracted on completing its rotary movement, the
lug 14 snaps into the prolongation 16 locking the screw to the carrier and
preventing the former from turning on its gudgeon as long as the mechanism is
open (Figure 4). On the other hand, when the carrier is returned to its
closing position (Figure 2), the outer end of the catch will be pushed in by striking
against the incline 17, the lug 14 consequently re-entering the groove 15 and on
being pressed forward again by its spring 13 when the breech screw has revolved
into its original position will snap into the recess 23.
The annular gas check disk 3, which makes the bore of the gun gas-tight bears
against the inner end of the breech screw and is held. in position by the part 2 of
the breech block that lies on the other side of it and is provided at the centre with
a spindle passing through the central portions of the breech screw and the gudgeon
on the lever or carrier 4 and fitted with a lock nut 30 screwed on its outer end.
This lock nut determines the amount of motion of the breech block in the breech
screw by coming in contact with a shoulder 32 in the hollow gudgeon of the
carrier 4. Ordinarily the breech-block is held against the gas check 8 by a special
spring 31 on its spindle, said spring being compressed between the lock nut and
the gudgeon.
The spindle of the breech block has a central channel 19 for the reception of the
firing pin or other firing arrangement. When a firing pin is used, a lever 18
forming the hammer is fulcrumed at the back of the carrier so as to be movable
towards the rear opening of the channel, this lever, however, by means of an arm 34
projecting from the safety catch in the direction of the centre of the breech screw
is prevented from coming in contact with the exterior end of the firing pin until
the mechanism is perfectly closed and the safety catch occupies its extreme position.
When an electrical firing-arrangement is employed, the wires of the circuit are
carried through the breech block and are provided outside of the latter with contact
pieces 28, 29, attached to the safety catch in such a manner that the circuit cannot
be completed until the mechanism is perfectly closed and the catch 12 has slipped
into the recess 23 at the rear end of the gun.
The mechanism operates as follows:
Supposing that the gun has just been discharged and that the mechanism is to be
opened (Figures 1, 2), then the safety catch 12 is in the first place pulled inward out
of the recess 28. The hand wheel 11'is subsequently rotated, this motion by means
of the gears 10, the worm 9, worm wheel 8 and spindle 7 being transmitted to the
roller which is also revolved. The groove 22 in the roller now causes the
segment 5 together with the breech screw meshing with it to revolve sufficiently
10 release the latter from the threads in the gun.
The rotation of the breech screw ceases when the arm 21 bas reached the end of the
groove 22, the roller having then revolved to the point where its slanting lug 33
comes against the guide 25 preventing further turning of the lever or carrier. On
continuing the rotation of the hand wheel, the worm compels the wheel S together
with the roller, the sliding carriage 24 and the breech screw to slide hackward
sufficiently to clear the lug 83 from the rear end of the guide (Figure 3), the
motion of the sliding carriage being arrested by the stop screw 26. The worm is
now free to swing the carrier the amount required for the complete opening of the
mechanism (Figure 4):
During the rotation of the breech screw, the breech block and gas check 3
remain at rest and it is only during the latter part of the receding motion of the
breech screw that the gas check is released from the bore of the gun when the
shoulder. 32 in the hollow gudgeon of the carrier strikes against the lock nut 30 of
the breech block. By the impact thus produced the gas check disk is extracted
with great force without any perceptible increase of effort being felt at the hand
wheel.

page_text: When the mechanism is to be closed, the band wheel is turned in the reverse
direction and the same movements as those just described take place only in the
reverse order.
It is evident that a reciprocating rack may be substituted for the worm 9.
Having now particularly described and ascertained the nature of my said inven--
tion and in what manner the same is to be performed, I declare that what [
claim is :-
1. In a breech mechanisin for ordnance provided with an ogival or conical breech
screw having threaded segments at its circumference and capable of revolving on a.
lever or carrier (4) that can be swung to one side on a hinge at the back of the gun,.
the combination of this hinge with a sliding carriage (24) movable longitudinally
with reference to the gun on a guide (25) secured to the latter, for the purpose of
admitting of a receding motion of the carrier together with the breech screw in
the direction of the axis of the gun, thus enabling the introduction in front of the
breech screw of a gas check (3) of the type known by the term "de Banges."
2. In a breech mechanism as described in the first claim, an arrangement for
moving the sliding carriage (24) consisting of a worm (9), or a rack that can be
shifted longitudinally, engaging with a worm wheel (8), or an ordinary gear, fixed
to the spindle (7) of the hinge, and of a bevel lug (33) projecting from the spindle,
the rear end of the guide (25) being located in the path of said lug (33), all for
the purpose of allowing of the lever or currier being at first swung on its hinge by
means of the worm or rack and subsequently shifted backward by the aforesaid lug
coming against the rear end of the guide anl preventing further turning of the
carrier, until the lug is free from the guide.
3. In a breech mechanism as described in the first claim an arrangement for
revolving the breech screw, while releasing it from or screwing it into the threaded
portions of the gun, consisting of a roller (6) fixed to the spindle (7) of the hinge
and provided with a groove (22) extending obliquely across the roller and having
less inclination at one end than at the other, said groove embracing one end of a
two-armed lever (5) fulcrumed at the inside of the lever or carrier (4), while the
other end has the shape of a toothed segment meshing with corresponding teeth on
the breech screw, all for the purpose of rotating the breech screw by turning the
spindle of the hinge.
4. In a breech mechanism as described in the first claim,
an arrangement for
locking the breech screw in its extreme positions after revolving it on its gudgeon,
consisting of a radially movable catch (12) attached to the rear end of the breech
screw and pressed outward by a spring (13), said catch being capable of entering
into a recess (23) in the rear end of the gun when the mechanism is closed and
being provided at the inside with a lug (14) which fits loosely into a circular
groove (15) at the outer side of the lever or carrier, this groove having a radial
prolongation outward at each end, one of these prolongations being located opposite
the recess (23) just mentioned and the other (16) situated opposite an incline (17)
at the point in the rear end of the gun where the catch will be situated when the
breech screw has received the full amount of rotation needed for the opening, all
with a view to keeping the catch withdrawn by the groove during the rotation of
the screw and allowing of its snapping forward at the extreme positions of the
breech screw.
5. In combination with the catch (12) an arm (34) projecting from the said catch
towards the centre of the breech screw and situated in the path of the outer end of
the hammer (18) as long as the catch is withdrawn, all for the purpose of preventing
the hammer from striking the firing pin and causing the discharge of the gun
until the mechanism is fully closed.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.