Improvements in Gas Checks or Obturators for Breech-loading Ordnance.
Year: 1889

page_text: Date of Application, 13th Nov., 1889
Complete Specification Left, 8th Aug., 1890-Accepted, 25th Oct., 1890
PROVISIONAL SPECIFICATION.
Improvements in Gas Checks or Obturators for Breech-loading
Ordnance.
I HENRI SCHNEIDER of Le Creusot in the Republic of France Manufacturer do
hereby declare the nature of this invention to be as follows:-
This invention relates to an improved arrangement of gas checks or obturators for
preventing the escape of gas at the breech of breech loading ordnance and combines
the advantages of a Broadwell ring and a plastic or clastic pad as hereinafter
explained.
An obturator according to this invention is provided with a thick ring of plastic
material such as a compound of mutton suet and asbestos surrounding the stem of
the obturator and arranged between two flat plates discs or washers whose surfaces
in contact with the pad are maile flat so as not to interfere with the lateral or radial
movements of the latter. At the two inner corners or edges of the annular pad or
ring of plastic material and at the two outer corners likewise there are provided
relatively thin flexible metal rings each made in one piece or solid of red copper or
other elastic material so as to admit of their expansion and contraction.
At the inner and outer edges of the annular plate or washer next to the head
there are likewise provided split rings interposed between the said plate and the
head.
The outer and inner circular or cylindrical surfaces of the gas check thus constituted
are so arranged as to allow of a small amount say from about 1 to 2 tenths of a
millimeter between them and the surfaces of the breech opening and the stem of
the obturator. This enables the opening and closing of the breech to be effected with
great facility.
When the shot is fired the ring of plastic material is compressed in one direction
between the flat plates and expands in another direction or radially so as to cause its
inner and outer surfaces to be applied closely against the stem and against the inner
surface of the bore or breech opening respectively thus effectually preventing any
escape of gas and the elastic metal rings being expanded by the pressure of the
plastic material prevent any escape of the latter at the corners or edges. On the
cessation of the pressure the flexible or spring rings return to their original
diameters and do not interfere with the ready removal of the obturator with the
breech block.
The flat plates or washers may be provided with dovetail or undercut recesses for
the reception of the rings at the same time allowing the latter to move radially and
when the head is made in one piece with the stem the rings under the head may be
lispensed with the plate being provided with an annular flange or ring embracing
the stem.
The plates or washers may be of any suitable metal the front plate is proferably of
ed copper and the rear plate of steel.
Dated this 12th 1 of 1000

page_text: COMPLETE SPECIFICATION.
Improvements in Gas Checks or Obturators for Breech-loading
Ordnance.
I. HENRI SCHNEIDER of Le Creusot in the Republic of France Manufacturer 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 an improved arrangement of gas checks or obturators 5
for preventing the escape of gas at the breech of breech loading ordnance and
combines the advantages of a Broadwell ring and a plastic or clastic pad as herein-
after explained.
An obturator according to this invention is provided with a thick ring of plastic
material such as a compound of mutton suet and asbestos surrounding the stem of the 1
obturator and arranged between two flat plates discs or washers whose surfaces in
contact with the pad are made flat so as not to interfere with the lateral or radial
movements of the said pad. At the two inner corners or edges of the said pad or
ring of plastic material and at the two outer corners likewise there are provided
relatively thin flexible metal rings each made in one piece or solid of red copper or
At the
other elastic material so as to admit of their expansion and contraction.
inner and outer edges of the annular plate or washer next to the head there are like-
wise provided split rings interposed between the said plate and the head.
The outer and inner circular or cylindrical surfaces of the gas check thus constituted
are so arranged as to allow of a small amount say from about 1 to 2 tenths of a
millimeter between them and the surfaces of the breech opening and of the stem of
the obturator.
This enables the opening and closing of the breech to he effected with great
facility.
When the shot is fired the ring of plastic material is compressed in one direction
between the flat plates and expanded in another direction or radially so as to cause its
inner and outer surfaces to be applied closely against the stem and against the inner
surface of the bore or breech opening respectively thus effectually preventing any
escape of gas and the elastic metal rings being expanded by the pressure of the
plastic material prevent any escape of the said material at the corners or edges. On
the cessation of the pressure the flexible or spring rings return to their original
diameters and do not interfere with the ready removal of the obturator with the breech
block.
The flat plates or washers may be provided with dovetail or undercut recesses for
the reception of the rings, at the same time allowing the said rings to move radially
and when the head is made in one piece with the stem the rings under the head may
be dispensed with, the plate being provided with an annular flange or ring embracing
the stem.
The plates or washers may be of any suitable metal the front plato is preferably of
red copper and the rear plate of steel.
And in order that this invention may be well understood I will explain with
reference to the accompanying drawing the manner in which the same is or may be
carried into effect.
Figure 1 represents in section an obturator applied to a moveable breech screw with
a moveable head C free upon the stem A attached to the breech screw B.
Figure 2 represents the obturator applied to a moveable breech screw with a
moveable head C made in one with the stem A of the breech screw B.
This composite obturator comprises
A plastic ring or pad D, two flat washers 1 and S; two split rings E and E¹ (in
the example shewn in Figure 1) and four elastic rings F F¹, G, G¹, each in one
11
hod (and the breech

page_text: The plastic ring D which may be composed of asbestos and mutton fat in the
usual proportions is enclosed between the two washers R and S one of which (the
front one) is provided with split rings E and E' in the arrangement Figure 1.
The washers R and S are made of any suitable metal but preferably the front
washer is of red copper and the back washer of steel. Their peculiarity lies in
their being flat and presenting no rin or projection either on the inside or on
the outside except in the special case illustrated in Figure 2 where the front washer
follows the profile of the rounded part connecting the stem A to the moveable
hoad C. In this case the corresponding elastic ring G₁ and split ring E' are
dispensed with.
The rings F F G G₁are each in one piece and are of triangular or other section
and are composed of cold hammered red copper or any other metal possessing a high
degree of elasticity. Their function is to support the external and internal edges
of the plastic ring or pad D.
The outer rings are connected to the washers R and S by means of a very shallow
undercut groove which returns them freely in position.
Between the obturator thus constituted and the sides or surfaces of the breech
chamber a vacancy or small amount of play is provided to the extent of from about
one tenth to one fifth of a millimetre. A similar amount of play is allowed between
the obturator and the stem A. This arrangement greatly contributes to ease tho
opening and closing of the breech.
Under the influence of the pressure of the gases resulting from the combustion
of the powder when a shot is fired the plastic ring D being passed between the
moveable head C and the breech screw is slightly flattened and expands transversely.
The expansion takes place externally towards the side of the breech chamber
and internally towards the stem of the movable head it is regulated by the internal
pressure and consequently prevents any escape of gases whatever. In expanding the
ring D carries with it in its movement the elastic rings F F G and G¹ which are
applied accurately against the bore and against the stem so as to prevent any
exudation of plastic matter between the surface of the joint.
When the pressure ceases the elastic rings return to their original form and the
aforesaid play reappears in the chamber and around the stem thus enabling the breech
to be opened with the same ease with which it was closed before firing.
This composite obturator can be constructed of any size so as to be applicable to
breech loading ordnance of any calibre.
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 :-
First The composite obturator or gas check formed by a plastic ring D two flat
washers R and S two split rings E and E' and four elastic rings F F G and G' each
in one piece all arranged between the moveable head C and the moveable breech
screw of the gun for the purpose of ensuring a gas tight joint under any pressure and
facilitating the operation of closing and opening the moveable breech as hereinbefore
described with reference to Figure 1 of the accompanying drawings, and also the
modification shewn in Figure 2.
Second-In this composite obturator the following particular arrangements
namely.
(a) The washers R and S flat on the surfaces in contact with the plastic
material so as to allow the said material perfect freedom to change its form
or shape whilst expanding the washers.
(6) The elastic rings F and F each in one piece which make the joint with
the sides of the chamber of the gun and the similar elastic rings G and G'
which make the joint with the stem A of the moveable head the said rings
being capable of sliding freely upon the washers hereinbefore specified with
reference to Figure 1 and also the modification of the foregoing as shewn
in Figure 2.

page_text: Third-The arrangement and combination of parts constituting the gas check
or obturator substantially as hereinbefore described.
Dated this 8th day of August 1890.
J. H. JOHNSON & Co.,
Agents.