Improvement relating to the Breech-mechanism of Guns.
Year: 1893

page_text: Date of Application, 22nd July, 1893-Accepted, 26th Aug., 1893
COMPLETE SPECIFICATION.
[Communicated from abroad by die FIRMA FRIED. KRUPP, GRUSONWERK, of
Magdeburg-Buckau, in the Empire of Germany, Manufacturers.]
Improvement relating to the Breech-mechanism of Guns.
1, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45 Southampton Buildings, in the County of Middlesex, 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 :—
This invention relates to breech-mechanism for guns, having a vertically sliding
breech-block which opens automatically by the action of its own weight as soon as
the projectile has left the gun, but which will remain closed before firing and as
long as the projectile is in the gun after firing.
Said invention is based upon the principle that the coefficient of friction between
bodies in motion is smaller than that between the same bodies at rest.
The accompanying drawing represents, partly in section, the breech end of a gun
fitted with a breech-block and operating lever constructed according to the present
invention.
A is the reinforce of a gun, provided with an opening for the reception of the
wedge-shaped breech block B. This block B is suitably guided in said opening
and can slide up and down therein. The direction of its motion forms with the
axis of the bore of the gun an angle a which is somewhat less than 90 degrees.
Therefore the plane front surface of the block which is perpendicular to the axis
of the gun and which always remains parallel to the rear end surface of the gun
will approach said rear end surface during the closing of the breech, and, sliding
along the base of the cartridge C, will push the said cartridge completely into the
cartridge chamber. The raising of the block is effected by means of a crank D,
the shaft a of which is supported behind the block in bearings 6 provided on the
under side of the reinforce. The pine of the said crank engages with a groove d
in the wall of the block. When the crank is turned in the direction to move the
pin e downward the block B which rests on the pin by the upper surface of the
groove d is depressed. On turning the crank D upward, the pin c, sliding with its
upper surface in contact with the upper surface of the groove d, returns to its
original position and in so doing raises the block. The crank and slot d are so
constructed and arranged that in turning the crank upward to its terminal position
the block continually rises; that is to say, in raising the block the crank does not
pass or even reach its dead-point position, in which position of the crank the
block would momentarily stop while the crank was further turned in the same
direction.
In the arrangement shewn in the drawing the line x-y drawn through the point
of contact of the upper surface of the pin with the upper surface of the groove d
in a direction perpendicular to this surface of the groove at that point, is always in
front of the axis of the shaft a. A component of the weight of the block, which
is applied to the point of contact and acts in the direction of the line a―y, will
then always tend, with a leverage equal to the distance of such line from the axis
of the shaft a, to turn the crank D downward, and therefore cause the block to
descend. To this tendency are opposed the following frictional resistances:-
(1) The friction at the edges e and ƒ of the block, due to the pressure
which the weight of the block produces at e and f, inasmuch as the block tends
to turn around the point of contact between the pin c and the upper surface of the
groove d.
(2) The friction which the component of the weight of the block, acting upon
the crank D in the direction a-u, produces at the point of contact itself.

page_text: (3) The friction in the bearing of the shaft a, produced by a component which
acts in the direction of the plane passing through the axis and the point of contact
of the pin c with the upper surface of the groove d.
If the sum of the moments of these frictional resistances is equal to or greater
than the turning moment of the component in the direction -y, the block will not
open automatically after the breech has been closed. If now a shot is fired, the
powder gases, as long as the projectile is in the gun, press the block forcibly
between the base of the cartridge and the rear surface of the breech aperture or
chamber so that the automatic opening of the breech is prevented. But as soon
as the projectile has left the gun this pressure ceases, and the crank D and
the block B, in consequence of the vibrations of the gun, are set in vibratory
motion. As the coefficient of friction between bodies in such motion is sinaller than
that between the same bodies at rest, the weight of the block will then overcome
the frictional resistances so that the breech will be opened automatically.
In the case of sliding breech-blocks heretofore known, the form of the groove d
and that of the pin and their arrangement relatively to the position of the axis of
the crank are such that in closing the breech the breech-block will reach its
highest position before the crank has quite passed to its terminal position, and while
the crank is turned to the latter position either remains stationary or descends
slightly again. In the first case the line a-y during the latter portion of the
turning movement of the crank, and therefore also in the terminal position of the
crank, will extend through the axis of the crank shaft. The turning movement of
that component of the weight of the breech-block which acts in the direction of the
linery, is therefore nil in the closed position and the automatic opening of the
breech-block by its own weight is prevented by the frictional resistances. In
the second case the line -y passes behind the axis, and the weight of the block
then tends to turn the crank D, not however in the direction for opening the breech
but in the direction for closing the same.
Therefore the present invention is distinguishable from former arrangements in
respect of the characteristic feature that throughout the turning of the crank to
effect the closing of the breech, the block is raised continuously to its highest
position.
The herein-described improved breech-mechanism not only facilitates the service
of the gun but constitutes also a security both for the gunners and the gun against
the action of after-burning.
To prevent the opening of the breech-block during transport of the gun it is
provided with a lock, which is removed when the gun is to be fired.
Having now particularly described and ascertained the nature of this said inven-
tion, and in what manner the same is to be performed, as communicated to me by
my foreign correspondents, I declare that what I claim is:
1. A gun provided with a breech block which, when closed, is retained in that
position by friction as long as the gun is at rest or before the projectile has left the
muzzle of the gun, but which will open automatically when the gun is shaking or
vibrating and the projectile has left the muzzle.
2. A vertically-sliding breech-block which opens the breech automatically after
the firing of the gun, and which is characterized by such an arrangement of the
axis of the crank shaft and the sliding surfaces of the crank pin and the groove in
the breech-block, that in the closing of its breech the crank does not reach the
dead point position, for the purpose specified.
3. A gun provided with a breech-block and breech opening mechanism con-
structed substantially as described with reference to the drawings, and operating as
specified.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.