Improvements in or relating to Pneumatic Guns.
Year: 1890

page_text: Date of Application, 22nd Feb., 1890
Complete Specification Left, 12th Aug., 1890-Accepted, 8th Nov., 1840
PROVISIONAL SPECIFICATION.
Improvements in or relating to Pneumatic Guns.
A communication from HENRY EICHBAUM, of the Grand Hotel du Louvre,
Boulogne-sur-Mer, in the Republic of France, Engineer.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
M.I.M.E., do hereby declare the nature of this invention to be as follows:-
This invention relates to that class of rifle gun or cannon in which the projectile is
"fired"
or expelled from the tube or barrel by means of a charge of compressed air
or gas instead of by the explosion in the barrel of a charge of powder or equivalent.
The present invention is particularly designed for the requirements of portable or
semi-portable guns although it may also be applied to fixed ones.
Hitherto where the pressure has been obtained by the use of liquefied gas,.
such as carbonic acid, anhydrous ammonia, or nitrous oxide the liquefied gas has
been contained in a reservoir or vessel, and when it was desired to discharge the
projectile connection was opened between the reservoir and the barrel and the liquefied
gas expanding in the barrel discharged the projectile. A drawback however to this
arrangement is the possibility of the vaporisation of the fluid not taking place instan-
taneously or so completely that the projectile will always leave the barrel at the
same velocity thus varying the range and interfering with the reliability of the
weapon.
This difficulty I propose to meet by employing a gas reservoir or chamber between
the barrel of the gun and the reservoir of liquefied gas. The liquefied gas is allowed
to enter the intermediate reservoir as required where it remains in a gaseous form and
from which it is admitted to the gun barrel or tube. The size and position of the
intermediate reservoir may vary according to circumstances and any suitable form
of valve mechanism or equivalent may be adopted for regulating the passage of
the gas.
Another difficulty is also met with in the furnishing of portable pneumatic guns of
this nature, viz., that excepting with the use of liquefied gas which is attended with
certain drawbacks, that of cost for example, it is very difficult to carry any consider-
able number of charges of compressed air or gas; this difficulty I propose to surmount
in the following manner :-I employ powder or equivalent which upon exploding
generate or liberate gases and by either generating or collecting these gases in a
suitable reservoir or vessel I obtain the pressure required. When the pressure is.
reduced by firing I discharge so many more cartridges or so much more of the powder
and thus restore the pressure in the reservoir.
The cartridges or powder may be discharged in any convenient manner as by
detonators or by an electric current and their discharge or explosion may tako
place either in the reservoir itself or in a firing chamber in connection therewith.
For this purpose it is not necessary that the powder used should be such as explodes
with great violence, and such as liberate fixed gases are preferable to those which (liko
common gunpowder) leave a residue, which would foul the interior of the reservoir
or the firing machinery of the gun.
Dated this 22nd day of February 1890.
W. P. THOMPSON & BOULT,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to Pneumatic Guns.
A communication from HENRY EICHBAUM, of the Grand Hotel du Louvre,
Boulogne-sur-Mer, in the Republic of France, Engineer.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
M.I.M.E., 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 that class of gun or cannon in which the projectile is
"fired
or expelled from the tube or barrel by means of a charge of compressed
air or gas instead of by the explosion in the barrel of a charge of powder or
equivalent. The present invention is particularly designed for the requirements of
portable or semi-portable guns although it may also be applied to fixed ones.
Hitherto where the pressure has been obtained by the use of liquefied gas, such
as carbonic acid, anhydrous ammonia, or nitrous oxide the liquefied gas has been
contained in a reservoir or vessel and when it was desired to discharge the projectile
connection was opened between the reservoir and the barrel and the liquefied gas
expanding in the barrel discharged the projectile. A drawback however to this
arrangement is the possibility of the vaporisation of the fluid not taking place
instantaneously or so completely that the projectile will always leave the barrel
at the same velocity thus varying the range and interfering with the reliability
of the weapon.
This difficulty I propose to meet by employing a gas reservoir or chamber between
the barrel of the gun and the reservoir of liquefied gas. The liquefied gas is allowed
to enter the intermediate reservoir as required where it remains in a gaseous form and
from which it is admitted to the gun-barrel or tube. The size and position of the
intermediate reservoir may vary according to circumstances and any suitable form of
valve mechanism or equivalent may be adopted for regulating the passage
of the gas.
In this arrangement the gun becomes a strictly pneumatic gun in which however
the pressure is generated by the liberation into gaseous form of a liquefied gas instead
of by air compressing machinery.
Another difficulty is also met with in the furnishing of portable pneumatic guns of
this nature, viz. that excepting with the use of liquefied gas which is attended with
certain drawbacks, that of cost for example, it is very difficult to carry any consider-
able number of charges of compressed air or gas; this difficulty I propose to surmount
in the following manner :-
I employ powder or equivalent which upon exploding or igniting generates or
liberates gases and by either generating or collecting these gases in a suitable reservoir
or vessel I obtain the pressure required; from this reservoir by any suitable arrange-
ment of valve mechanism 1 can admit the gas as needed to the gun tube. When the
pressure is reduced by firing I discharge so many more cartridges or so much more of
the powder and thus restore the pressure in the reservoir.
The cartridges or powder may be discharged in any convenient manner as by
detonators or by an electric current and their discharge or explosion may take
place either in the reservoir itself or in a firing chamber in connection therewith.
For this purpose it is not necessary that the powder used should be such as explodes
with great violence, and such as liberate fixed gases are preferable to those which (like
common gunpowder) leave a residue, which might foul the interior of the reservoir
or the firing machinery of the gun.
The accompanying drawings serve to show one way in which this invention may be
carried into effect but as it will be observed that apparatus varying widely in
character and detail may be employed for this purpose these drawings serve merely
as illustrations to enable the invention to be thoroughly understood.
Figure 1 is a plan of apparatus suitable for applying the liquefied gas to a
pneumatic cannon.

page_text: Fig. 3 is a horizontal section,
Fig. 4 an internal end elevation, and
Fig. 5 an external end elevation, of apparatus suitable for obtaining pressure from
the discharge of cartridges.
Fig. 6 is a vertical section of one of the chambers shown in Fig. 3 and
Fig. 7 is a cross section showing the interrupted screw arrangement of the breech
closing device of the chambers.
Fig. 8 represents each of the reservoirs B fitted with an explosion chamber K the
reservoir D being in this instance dispensed with.
Like letters represent like parts throughout the drawings.
In Fig. 1, A represents the hollow pintle by which the pressure is conveyed to
the cannon, A¹ being the conduits conveying it to the pintle from the reservoirs B
which in the drawing are shown as consisting of six tubular vessels on each side of the
pintle and connected with cross tubes B¹ which are braced together by the tie rods B².
This particular form of reservoir is shown here as it is that which I have fully described
and illustrated in my previous British Patent No. 6369 of 1889. This reservoir B is
the intermediate gas reservoir or chamber employed between the barrel of the gun
and the reservoir of liquefied gas. This latter reservoir is shown at C connected with
the intermediate reservoir B by a pipe C in which is a valve or cock C" so that when
the pressure in B is lowered it can be raised again as required by opening the
valve and allowing some of the liquid from U to expand into the gaseous form the
valve being reclosed when the requisite pressure is attained in B. In this drawing
two of these reservoirs C are shown one connected with each reservoir B; the
reservoirs B however are not independent as they are connected by the conduits A¹
which unite at the pintle A so that a uniform pressure is obtained in both sets of
reservoirs, the two reservoirs C being merely shown as a convenient arrangement by
which they can if necessary, be alternately employed and recharged with the
liquefied gas.
This drawing refers to heavy guns or artillery and would not be applicable to small
portable guns or small arms; it will be understood however that this invention is
applicable to rifles and small arms as well as to field artillery, it being merely a question
of the arrangement of the reservoir for the liquefied gas and the intermediate reservoir
in which the gas is retained in a gaseous form the exact shape, construction and
connection of these parts being immaterial.
As an illustration however of one manner in which this invention may be
applied to rifles and similar small arms I have introduced Fig. 1ª in which a is the
gun barrel, 6 is the chamber containing the gas in a gaseous form and c is the chamber
containing the gas in a liquefied form, d represents the trigger and e the cock,f the
h is the inlet for the
valve to the chamber b, and g the valve to the chamber c.
liquefied gas and i is a screw cap to close the same. Instead of the cap i an ordinary
plug cock or valve may be employed preferably having a projecting branch or
internally screwed coupling by which it may be connected with the supply of liquefied
gas. The action of this arrangement is as follows:-
In cocking the rifle the cock e is drawn back in the usual manner turning upon its
pivote and as it does so the projection; bears upon the jointed end k of the bell
crank lever whose other arm m is in contact with the spindle of the valve g.
Therefore as the cock e is turned on its pivot, j coming in contact with k causes m to
bear upon the spindle thus opening the valve g, but as the movement of e continues
is carried past k which is thus allowed to return to its normal position. This it will
do under the influence of the pressure in c or a spring may be provided if desired.
Upon the return of the cock to its normal position as shown in full lines in the
drawing slips past k carrying it along with it so far as necessary when k clears j and
returns preferably under the influence of a spring to its normal position as shown in
the drawing. By this arrangement it will be seen that every time the gun is cocked
a passage is opened between the chambers c and 6 whereby the pressure in 6 is

page_text: restored, a portion of the liquefied gas escaping from c and assuming the gaseous
form in b.
The valve which admits the charge of compressed gas into the barrel a behind the
bullet is momentarily opened by the recoil of the cock e under the influence of the
spring n when freed by the movement of the trigger d the valve instantly
closing again under the pressure in b.
The power of the spring n is preferably adjusted so as to enable the cock e to open
the valve f by the sudden blow after its release by the trigger, but not to maintain it
open against the pressure in b.
In Figure 2 is shown a plan which generally is similar to the apparatus shown in
Figure 1 but instead of the reservoirs C are employed reservoirs D provided with
means such for example as the explosion chamber K for exploding in these reservoirs
or conveying to them the products of the explosion or ignition of cartridges powder
or the like for the purpose of raising the pressure in the reservoirs D and B. In
Figure 2 two of these reservoirs D are shown one connected with each set of the
intermediate reservoirs B but here again it is not absolutely necessary that more than
one of the reservoirs D should be employed but it is convenient to do so and it will
be understood that I do not limit myself to the number of reservoirs whether D or C
that may be employed. Also in the case of the reservoirs D the presence of the
intermediate reservoirs B is not essential as they are in effect merely extensions of the
reservoirs D so that if these latter are made sufficiently capacious as at D' for example
the requisite supply of compressed gas may be obtained without the intervention of
any intermediate or supplementary reservoirs. If the apparatus represented in Fig. 2
were constructed complete of course the two reservoirs D would be made of the same
size, as indicated in dotted lines at D¹.
Or a separate explosion chamber K may if preferred be attached to each of the
vessels B as shown in Fig. 8 in which case the reservoirs D can be dispensed with.
The apparatus for containing the powder (which I prefer to use in the form of
cartridges) and in which it may be exploded or ignited will be best understood by
reference to the drawings. Figs. 3 to 7. which I will now proceed to explain. In
Figs. 3 to 6 is illustrated the Box or casing containing the cartridges and chambers
in which they are exploded. This box K is shown provided with flanges K' by
which it may be bolted on to the reservoir D of Fig. 2 but it will be understood that
so long as the cartridge chambers communicate with the interior of the reservoir to
which they appertain it is immaterial in what particular way they are connected with
it. Each of the chambers E then, of which there may be any desired number,
connects with or enters into or may be contained in, this reservoir or conduit to
another reservoir D; so that the products of the explosions in each chamber pass into D
being retained there for use as required. Each chamber E is provided with a breech
block F or equivalent means for closing its open end and this block is preferably
connected with the chamber by means of an interrupted screw E¹ F¹ so that the block
may be inserted and then turned round sufficiently to firmly secure it in the chamber
in the manner commonly adopted with breech loading ordnance. At the inner end of
the chamber E is a gate, valve or equivalent device G connected with a spindle H
which may be turned by a handle H₁ so that by turning the spindle H all the gates G
can be simultaneously opened or closed as will be well understood by reference to
Figs. 3, 4 and 6 of the drawings. These gates or valves normally remain closed as in
Fig. 6 and while they are in this position the breech blocks F and cartridges can be
removed and replaced at pleasure without loss of pressure in the reservoir D. Each
gate is preferably provided with a packing ring G₁ adapted to fit upon the seating E
so as to make. a tight joint and facilitate repairs. The spindle H passes through a
stuffing box containing packings H by which a tight joint may be secure around it.
This spindle H is preferably square throughout its length except where it passes
through the stuffing box and gland, and carries at those portions where it obtains a
bearing in the metal surrounding the chambers E thimbles I, square inside so as to
fit upon and turn with the spindle H, but cylindrical or circular on their outer surface
so as to turn freely in the circular bearings provided for them. In Fig. 3 the spindle H

page_text: is shown broken at J the handle portion being shown in one position with the gate G
of the chamber E nearest to the handle closed, while the other portion remote from
the handle is shown at right angles to the handle portion and this remote portion
carries the gate G of the middle chamber E which valve is shown in its open
position.
As it would be a difficult matter to open these valves G against the pressure in the
reservoir D it is desirable to equalise the pressure on both sides of the valve and this
may be accomplished in the following manner. A passage L is provided in the wall
of the chamber one end of the passage opening to the reservoir side of gate G and
the other end into the chamber E; a plug L₁ preferably tapered at its end as shown,
and provided with a curved passage L'adapted when in proper position to communicate
with the passage L, controls these passages so that by turning this plug the commu-
nication between the reservoir and the chamber can be either established or cut off.
When this communication is cut off the gate G remains closed with the full pressure
of the reservoir upon it, but when the communication by the passage L is opened the
pressure upon the two sides of the gate G is equalised (the breech block F being of
course in position and closing up the chamber E at such time as this communication
is open) and the gate G can then be opened. Where the pressure.is so great that even
this balancing of the pressure on both sides of the valve is not sufficient a different
form of valve may be employed preferably a form of piston valve in which the areas
may be suitably arranged, or an automatic valve may be employed adapted to open
automatically while the pressure in the chamber E due to the explosion is greater than
that in the reservoir, closing again when the pressure in the reservoir exceeds that in E.
The plug L' may be held in its position by the cap R and the end of the plug is
tapered to effect a tight joint against the seating on which it works.
The cartridges M may be fired by any convenient means as by a detonator for
example, but preferably an electric current which may be introduced as follows.
Each cartridge is provided with two tubes N containing a wire O the two wires being
joined at the inner end of the cartridge by a platinum wire P; the tubes N are
carried in the base M' of the cartridge, the wire extending sufficiently far through to
make electrical contact with corresponding wires Q carried in the breech block F.
If desired the wires Q may terminate on the inner side of the breech block in
segmental contact plates so that proper contact may be ensured with the wires O
while allowing for the turning of the breech block after it has been inserted in the
chamber. By this arrangement of the wires the charge may be fired at any desired
point according to the length of the tubes N but it would be desirable usually to fire
the charge as near its inner end as possible and this would be accomplished by the
arrangement shown in Fig. 3 where the heated portion of the wire P is brought close
to the inner end of the cartridge. The operation of this portion of the invention is
as follows:-
It being desired to charge the reservoir the cartridge chambers are charged with
the cartridges and the breech blocks put in and screwed home, the gates G are opened,
the circuit completed and the cartridges discharged preferably in succession. The
gates G are then closed, the breech blocks and discharged cartridges removed, fresh
cartridges inserted and the breech blocks replaced, when the process is again gone
through and so on until the required pressure is obtained or restored to its initial or
normal limit. If automatic valves G were employed in place of the hand operated
gates the opening and closing of the valves would not require to be attended to, the
chief object of the gate valve or other their mechanical equivalent being to prevent the
escape of pressure while the cartridges are being charged or other arrangements
made for additional explosions or ignition. Therefore if for example cartridges were
so arranged as to successively expel the discharged ones while still preventing the
escape of pressure that would represent the equivalent of the valve or gate G. It is
preferable to employ more than one set of cartridge chambers so that the cartridges
in one set of chambers may be discharged while those in another one are being
replaced.

page_text: .
Having now particularly described and ascertained the nature of the said
invention, as communicated to me by my foreign correspondent, and in what manner
the same is to be performed, I wish it to be understood that I am aware that it
has before now been proposed to obtain pressure in a roservoir by the explosion
or ignition of gunpowder or the like and that the mere use of liquefied gas for
discharging the projectile is known and that I make no general claim thereto. So
far as I am aware however it has never before been proposed to renew the pressure
thus obtained when reduced by use or leakage until the pressure has entirely gone
nor to allow of the expansion of the liquefied gas before it enters the gun tube or
barrel, nor can I find that any apparatus has been devised for these purposes;
whereas by this present invention the pressure can be renewed at any time and with
any pressure short of the top limit existing in the .reservoir, and a portion of the
previously liquefied gas can be retained in a gaseous form ready for admission to the
gun tube and thus greater certainty in the discharging of the projectile ensured.
What I claim is :-
-
1. The method of employing liquefied gas for the propulsion of projectiles by
allowing it to assume a gaseous form in an intermediate chamber before admitting it.
to the projectile.
2. The combination with the reservoir of liquefied gas and the gun tube or barrel
to which it is to be admitted for the purpose of discharging the projectile of an
intermediate reservoir or chamber into which the liquefied gas enters and in which
it assumes a gaseous form before being admitted to the gun barrel substantially as
described.
3. In a pneumatic gun the combination with the pintle A by which the pressure is
supplied to the gun and the reservoir C for liquefied gas of an intermediate reservoir
or chamber such as B substantially as and for the purpose described and illustrated
in Fig. 1 of the accompanying drawings.
.
4. In a pneumatic gun the combination with the pintle A by which the pressure is.
supplied to the gun of a reservoir such as B D in which the pressure is maintained
by successive discharges substantially as described and illustrated in Figure 2 of the
accompanying drawings.
5. The combination with the explosion chamber of a pneumatic gun of a valve or
gate such as G for the purpose of enabling the pressure to be restored by repeated
explosions substantially as described.
6. The combination with the reservoir of a pneumatic gun of an explosion box
or casing such as K containing one or more explosion chambers such as E each having
a removable breech block F and a gate or valve such as G substantially as described
and illustrated in Figure 3 of the accompanying drawings.
7. The combination with the reservoir of a pneumatic gun of an explosion chamber
such as E normally separated from the reservoir by a gate or valve such as G and having
a pressure equalising device such as L L L the whole constructed and operating
substantially as and for the purpose described and illustrated in Figure
accompanying drawings.
of the
8. The method of renewing the pressure in a reservoir for a pneumatic gun
after the same has been reduced and without the necessity for still further or
entirely reducing it by means of successive explosions er ignitions adding their pressure
to what may be still existing in the reservoir substantially as described.
9. The combination and arrangement of parts constituting the complete explosion
box or chamber substantially as described and illustrated in Figure 3 of the accom-
panying drawings.
W. P. THOMPSON & BOULT,
Agents for the Applicant.