Improvements in Gas Checks for Projectiles.
Year: 1895

page_text: Date of Application, 29th Oct., 1895-Accepted, 7th Dec., 1895
Improvements in Gas Checks for Projectiles.
I, HUDSON MAXIM, of 41 Wall Street, in the City County and State of New
York, United States of America, Chemist, do hereby declare the nature of this
invention to be as follows:-
My present improvements relate to gas checks for ordnance projectiles, having
for their object to more promptly and effectually close the space or windage
between the shell or other projectile and the walls of the bore of the gun,
thereby preventing erosion of the bore by the rushing of the gases past the
projectile.
To this end I provide a gas check which will, upon firing, be forced against and
between the lands of the gun with a pressure of greater degree than that of the
propelling explosive charge.
In order that the gas check may have this mode of operation I construct_and
arrange it relative to the projectile so that the gas pressure of the propelling
charge is, in the course of transmission to that external area of the gas check which
engages the bore of the gun, multiplied or increased. The gas pressure may be
applied directly to the inner surface or area of the check, or it may be applied
through the medium of another body, such for instance, as a body of lead or other
soft substance capable of flowing under pressure. In case of the said direct
application of the gas pressure, the inner surface of the gas check which is
presented to the propelling gases of the explosive charge, receives an unbalanced
outward pressure over an area which engages the lands of the gun. Said external
area, the contact of which with the bore of the gun forms the barrier to the
passage and erosive action of the gases, is thus forced and held against the walls
of the bore with very great pressure and rendered most effective for the purpose.
In case of the indirect application of the gas pressure to the inner surface of the
check I arrange beneath the latter a confined body or ring of lead or other soft
substance and provide means whereby the gases of explosion may compress said
soft body or ring and cause the same to press outwards against the inner side of
the gas check with great force.
With such object in view and having the mode of operation above briefly
described, my invention consists in the parts and combinations thereof hereinafter
set forth and claimed.
In order to make the invention more clearly understood I have shown in the
accompanying drawings means for carrying it into practical effect, without
limiting my improvements, in their useful applications, to the particular
construction, which, for the sake of illustration, I have delineated.
drawings:
In said
2
Fig. 1 is a side view, partly in section, of a projectile having a gas check
embodying my invention."
>
Fig. 2 is a transverse sectional view of a portion of the same on a larger scale,
on line II-11, Fig. 1.
Fig. 3 is a sectional view on line 111-111, Fig. 2.
Figs. 4 and 5 are similar views, showing other slightly different forms of gas
checks also embodying my invention.
Figs. 6 and 7 are sectional views on line VI-VI, Fig. 4, and line VII-VII,
Fig. 5, respectively.

page_text: Figs. o to 25 are longitudinal sectional views of other forms of check, also
embodying the invention.
At or
Referring to the drawings, 1 indicates the body of the projectile, that
illustrated being a shell of ordinary form.
near its rear end said
projectile is formed with a peripheral groove 2 which is undercut or dove-tailed
as shown.
The gas-check is indicated at 3, consisting of an annulus of metal such as copper,
and formed on its inner surface with a ring 4 which is shaped to fit the groove 2
and through which the forward or driving gas pressure on the gas-check is com-
municated to the projectile. Formed with the driving ring 4 is the outwardly
movable part 5 of the gas-check having an outer surface 6 adapted for contact
with the lands of the gun, and to be forced into the grooves thereof. The driving
ring thus acted upon by said groove also serves to impart to the projectile the usual
rotary motion. In that form of invention illustrated in Figs. 1 to 15, the gas
check is indirectly acted upon by the gases of explosion as above referred to.
14 is a body of lead or other soft metal or alloy or other substance, situated in a
confined annular space or chamber formed for its reception in the body of the
projectile. This body of soft metal 14 is adapted to flow under sufficient pressure,
and, if confined so that it cannot flow forward, inward or backward, it will press
outward upon the inner face of the gas check. The pressure for this purpose is
caused by the explosion of the powder charge behind the projectile and may be
applied to the body 14 in various ways, the means or present device for this
purpose, however, acting upon the body 14 through or over an area less than that
which the said means or device presents to the propelling gases. In Figs. 1, 2
and 3, the pressure device adapted to act upon the body 14 consists of a ring 15
composed of two or more sections and situated in a groove around the projectile at
the rear of the body 14 and beneath the gas check. The forward edge of the
pressure device 15 is preferably reduced in thickness, so that it will act upon a
comparatively small area of the body 14. The free forward movement of the
thicker rear part of the said device is permitted by leaving beneath the ring a.
clear space 7.
At its rear end the pressure device 15 is preferably enclosed by a
thin portion or flange 16, of the gas check which thus forms a gas-tight covering
through which the gas pressure is communicated to the ring 15. The gas check
is composed of copper or equivalent metal, and at that point where it is forced
outward against the lands of the gun as above described, it is formed with grooves
or spaces 17, for the purpose of allowing the gas check to yield forward or be
compressed forward by the propelling gases, the added material between said
grooves 17 serving at the same time to strengthen the gas check and relieve the
pressure device 15 of a portion of the inward pressure which might tend to crush
or confine it and prevent its forward movement.
Referring to Figs. 4 and 6 the pressure devices consist of a series of individual
pins or plungers 18, which pass through bearing apertures 19 against the rear
surface of the ring 14. When said pins are forced forward by the gases of explo-
sion the substance of the ring 14 will be compressed and, being otherwise confined,
will be caused to flow outward against the inner surface of the gas check and
force the latter against the lands of the gun. The rear ends or heads 20 of the
pins 18 are of considerably greater area than the forward ends which bear against
the ring 14, and are adapted to slide forward in bearings or cylinders 21 formed in
the projectile. The degree of pressure is thus multiplied or increased in the course
of its transmission to the inner surface of the gas check."
In the construction shown in Figs. 5 and 7 there are provided a series of
individual pins or plungers 22, adapted to act through bearings 23 upon the ring 14,
which pins are carried or actuated by a continuous pressure ring 24, secured to
their outer ends, adapted to play in an annular recess 25 formed in the rear end
of the projectile and serving to transmit to said pins, and thence to the ring 14,
the entire pressure which it receives from the gases of explosion upon its entire
' and continuous rear face. The said rear face may be slightly concave as indicated

page_text: at 26, in order that the gas pressure may cause the ring 24 to pack the recess 25, and.
prevent the passage of the gases. A similar formation may be given to the heads 20.
of the pins 10 already described.
In Figs. 8 and 9 the rear side of the pressure device is not covered by any portion
of the gas check and it is exposed directly to the gas pressure. In Fig. 9 a portion
of the ring 14 enters a corresponding recess in the inner face of the gas check as.
indicated at 27, thus somewhat weakening the latter and localizing the interior
pressure upon it and its outward movement.
Referring to Fig. 10, it will be seen that the ring 14 may be arranged to be
directly acted upon by the gases of the propelling charge. The rear face 28
of the ring which thus receives said pressure is preferably made, as illustrated,
of less area than the area over which the ring presses upon the inner face of the
gas check.
In Fig. 11 a pressure device, or devices, is employed bearing on the ring 14 and
actuated by a separate gas packing ring 29, lying beneath the gas check.
In Fig. 12 a series of presser pins or plungers is employed to cause the flow
of the ring 14, said plungers entering directly through and having their heads
exposed at the base of the shell. In this construction the outer face of the gas
check may be grooved as shown and said grooves charged with a soft metal 30,
adapted, together with portions of the gas check, to be forced into the grooves
of the gun and more perfectly occlude all spaces between the projectile and the
bore.
In Fig. 13 the pressure pins are arranged as in Fig. 12, and the ring 14 enters
an annular recess in the inner face of the gas check, as already described in
connection with Fig. 9.
In Fig. 14 the pressure pins are arranged as last above described, but the ring 14
is situated entirely within the body of the gas check, and the latter is formed with
openings 31 in its outer surface through which portions of said ring may be caused
to flow into the space between the gas check and the bore of the gun, operating
together with the expanded gas check to more perfectly fill said space. The
passages which lead outward through the gas check from the main body of the
ring 14 to the openings 31 are preferably choked or contracted as shown at 32, in
order that the outward flow of the substance of the ring may not be too free and
may not fail to cause upon the inner surface of the gas check the desired outward
pressure, which will expand the latter against the bore of the gun. It will be
understood that the areas of the openings 31 may be larger in proportion than
indicated in the said figure.
In Fig. 15 the pressure pins are arranged as shown at 33 to move and enter the
body of the ring 14 at an angle to the axis of the projectile.
In Figs. 16 to 23 I have illustrated a form of gas check in which the outward
gas pressure upon it is applied directly without intervention of any other body or
pressure device. In this form of the invention the inner face or area 34 of the.
gas check is adapted to receive the direct pressure of the propelling gases, which
enter the chamber 35 beneath the check through passages 36. In order to give
a certain degree of plasticity to the check portion so that it will more readily
enter and fill the grooves of the gun bore, and in order to form its exterior portion
of less area than its inner face 34 I prefer to form said check portion with
chambers, recesses, or grooves of considerable width and of a depth extending
below the surface of the projectile, so that the bottoms of the grooves will never
meet the lands of the gun, and so that the metal of the projections upon opposite
sides of the grooves will never be sufficiently mashed down into the grooves to
materially change the normal exterior area of the check. These grooves may be
left empty or filled with a metal or alloy which is softer than copper, such as an
alloy of lead and tin, as indicated at 11, in Fig. 17. A similar soft-metal filling is
shown in Figs. 18, 20, 22 and 23. This soft metal offers little resistance when the
check is forced against the lands of the gun so that its area is not considered in
estimating the amount of surface of the gas check proper and its degree of pressure

page_text: on the bore of the gun. By making the surface 7 concave as shown in Fig. 17,
with comparatively thin edges the pressure of the propelling gases in the chamber 8
will cause the ring 4 to pack the groove 2 against any outward escape of gases from
said chamber.
The part of the gas check which fits within the groove 2 of the projectile may
he dovetailed as already mentioned and held from outward movement where it is
so overhung by portions of the projectile. In such case a neighbouring portion of
the gas check is left free to move outward, and such free portion has the bore-
engaging surface 6, and beneath it is arranged the pressure space or chamber 8.
In Figs. 18, 20 and 22, such free part of the check is situated at one side of (at
the rear of) the ring 4. In Fig. 21 the middle part of the gas-check between its
dovetailed and overhung edges is adapted to buckle or yield outward under the
pressure from within the chamber 8. The front and rear portions of the gas-check
may be formed with separate rings 12 and 13 each dovetailed and fitting in a
corresponding groove in the projectile, and having between them the chamber 8.
Such constructions are shown in Figs. 19 and 23. The gas openings into the
chamber 8 may lead from the rear of the shell or from points at the side of the
latter behind the gas-check or entirely through the body of the gas-check.
The exterior of the gas-check may be made in various forms as illustrated.
The check portion 5 may be situated at the rear of the interior surface 7 as to
cut off from the exterior of the gas-check the direct or exterior gas pressure which
might otherwise tend to press the gas-check inward and balance the outward
pressure in the chamber 8. The check portion 5 is thus more effectually left
unbalanced, as between exterior and interior pressures, and acts under the full
effect of the latter.
In order to obviate any possibility of downward or balancing pressure on the
outer surface of the check portion 5, by reason of the forward driving ring being
forced against the lands of the gun and confining the gases behind it, I prefer to
form in the said driving ring openings or grooves 14 (Figs. 21 and 22) which will
permit the free passage of gases from the space over the chamber 8.
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 I
claim is:
1. A gas-check for projectiles having an inner area for receiving gas pressure,
and a check portion having a surface for engaging the lauds of the gun of less
area than said inner surface, substantially as set forth.
2. A gas-check for projectiles having an inner area exposed to gas pressure, a
check portion having a surface for engaging the lands of the gun of less area than
said inner surface, and a driving ring, substantially as set forth.
3. A gas-check for projectiles having an inner area exposed to gas pressure, a
check portion having a surface for engaging the lands of the gun, and a driving
ring portion forward of said check-portion and formed with openings for the escape
of gases, substantially as set forth.
4. In a gas-check the combination with a projectile, of a ring having its inner
surface adapted to receive the propelling gas pressure, and its outer surface
consisting of two metals one more yielding than the other, substantially as set
forth.
5. A gas-check for projectiles having an inner area exposed to gas pressure, a
check-portion having a surface for engaging the lands of the gun grooved and
filled with soft metal, and a driving ring portion, substantially as set forth.
6. A gas-check having an inner surface for receiving outward pressure, and a
surface for engaging the bore of the gun, and means movable relative to the
projectile base, causing the latter surface to engage the bore of the gun with a
pressure of greater degree than that of the propelling gases, substantially as set
forth.
7. A gas-check for projectiles provided with a projection or ring for engaging
:

page_text: a recess of the projectile, having confined beneath it a continuous and soft material
adapted to yield or flow under pressure, substantially as set forth.
8. A gas-check for projectiles having confined beneath it a soft material, and a
pressure device normally independent of and movable relative to the projectile
base to be actuated by the propelling gases to cause the outward movement or flow
of said material, substantially as set forth.
9. A gas-check for projectiles having beneath it a soft material adapted to press
outwardly on the gas-check, and means for subjecting said soft material to a
pressure of greater degree than that of the propelling gases, substantially as set
forth.
10. A gas-check having beneath it a soft material, and a pressure device
engaging said material over an area less than the area which said device presents
to the propelling gases, substantially as set forth.
11. A gas-check for projectiles having beneath it a soft material, and a series of
pins or plungers independent of and movable relative to the projectile engaging
the latter and adapted to receive the pressure of the propelling gases, substantially
as set forth.
12. A gas-check for projectiles having beneath it a soft material, a series of
pins or plungers independent of and movable relative to the projectile engaging
the latter, and an outer ring for receiving the pressure of the propelling gases and
transmitting the same to said pins, substantially as set forth.
H. MAXIM,
Per W. H. Beck,
Agent.