Improvements in or relating to Pneumatic Guns.
Year: 1890

page_text: Date of Application, 2nd Jan., 1890
Complete Specification Left, 17th June 1890-Accepted 19th July 1890
PROVISIONAL SPECIFICATION.
Improvements in or relating to Pneumatic Guns.
A communication from HENRY EICHBAUM, of the 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 pneumatic guns and has particular reference to the
admission of the air or gas under pressure to the projectile. Hitherto this has been
accomplished by opening one or more valves and applying at once the full air
pressure to the valve, but it being desirable to avoid as much as possible any too
violent shock upon the projectile which carries generally an enormous bursting charge
of some high explosive, it is now proposed that the initial pressure applied to the
projectile shall be lower than that which discharges it from the tube.
This invention it will be seen may be applied in various ways and various devices
may be used in carrying it out, but I will now describe one way of carrying the
invention into effect which will be sufficient to indicate the general lines of its
application.
As an illustration then of how this invention may be carried into effect I proceed
as follows:-In connection with the breech end of the gun or tube I may employ a
hollow belt communicating in any desired way with the interior of the tube, the
capacity of this belt being preferably equal to the capacity of that portion of the tube
between the projectile, when in place in the tube before it is started, and the inner
side of the breech block. The connection between this belt and the interior of the
tube may be made in any convenient manner. The belt may be in communication
with the full air pressure employed and is designed to be cut off therefrom when
the pressure inside the belt equals that of the supply; we now have a pressure inside
the belt and none inside the tube. Upon opening communication between the belt
and the tube the air or gas in the belt passes into or communicates pressure to the
interior of the tube behind the projectile and in the instance we have given, the total
pressure both in the tube and in the belt would be reduced by about one half and
would be we will say for example 1000 lbs. to the square inch, which would be the
pressure which would start the projectile on its course down the tube. Means may be
employed for delaying the movement of the projectile if desired but such means form.
no part of the present invention. The projectile having been started on its course-
may cause communication to be made between the interior of the tube and the higher
pressure, and here again various devices may be employed and the introduction of the
higher pressure may take place at any portion of the journey along the tube though
it would generally be preferred to introduce it before the projectile had travelled far.
One method of introducing the higher pressure is to have one or more openings
or ports communicating between the interior of the tube and a valve which would
either directly or indirectly control the admission of the full pressure into the tube.
As the projectile travelled down the gun it would uncover these ports and cause an
inrush of the higher pressure (directly through these ports or by allowing the pressure-
in the tube to pass out by these ports and operate valve mechanism) behind it the
cutting off of that pressure being controlled in any required manner as by one of the
known valve mechanisms.
Another way of effecting the introduction of the higher pressure would be to have
a lever, pin, latch or equivalent which would be held back by the projectile so long as
it was in the requisite position, but which when the projectile passed beyond it would
be released and by any desired means effect the entrance of the higher pressure, the
subsequent cutting off of the pressure being effected in any convenient manner as
before..

page_text: If preferred the mechanism which controls the admission of the initial charge may
be made to control also the subsequent admission of the higher pressure either by
allowing a stated interval to elapse or by operating directly upon the higher pressure
admission. Or the initial pressure may be admitted directly from the highest pressure
by a reducing valve or merely a small tube the controlling valve of which would thus
regulate the admission of both pressures and be the only one the operator would have
to work.
I may divide the gun into sections each adapted to its own pressure and arranged
for the closing of diaphragms or doors behind the projectile as it passes so that the
pressure in each succeeding section may be higher than and more or less inde-
pendent of the pressure in the section behind it. The diaphragms and valves
may be operated together or independently in pairs or otherwise by any suitable
means.
Dated this 2nd day of January 1890.
W. P. THOMPSON & BOULT,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in or relating to Pneumatic Guns.
A communication from HENKY EICHBAUM, of the 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 pneumatic guns and has particular reference to the
admission of the air or gas under pressure to the projectile. Hitherto this has been
accomplished by opening one or more valves and applying at once the full air pressure
to the projectile, but it being desirable to avoid as much as possible any too violent
shock upon the projectile which carries generally an enormous bursting charge of
some high explosive, it is now proposed that the initial pressure applied to the
projectile shall be lower than that which discharges it from the tube.
This invention it will be seen may be applied in various ways and various devices
may be used in carrying it out but the following specification will be sufficient to
indicate the general lines of its application.
The invention will be best understood by reference to the accompanying drawings
in which
Fig. 1 is a longitudinal section through the gun tube and side pipes on the line z-2
of Fig. 4.
Fig. 2 is a longitudinal section on the line y-y of Fig. 4.
Fig. 3 is a cross section on the line - of Fig. 2, and
Fig. 4 is a cross section on the line w-w of Fig. 2.
Fig. 5 is a section of the valve F.
Figs. 6 and 7 are sections of the valve E with the plug in different positions.
Fig. 8 is a section of the breech end of the gun tube of a form slightly modified
from that shown in Figs. 1 and 2.
Figs. 9 and 10 show a valve or stopper for the hole B¹.
Like letters indicate like parts in all the figures.
Referring first to Figure 1, A is the gun tube or barrel and B the sile pipes or
branches by which the air pressure is conveyed to the firing valve C. D are two
air-belts shown arranged around the side pipes; a single air-belt however might be
employed around the gun tube but as it is desirable to maintain as much as possible
a balance of pressure and dynamic effect in the operation of the gun the two belts D
are preferably employed which discharging their contained pressure into the gun
barrel A upon opposite sides maintain the desired balance, besides rendering the

page_text: various parts more accessible. These supplemental reservoirs D could be placed
otherwise and away from the gun but the arrangement described above is preferred.
EE are controlling valves connected together by any suitable mechanism so that
upon the operator moving one of these valves he of necessity and similarly operates
the other. E' is a branch communicating with the atmosphere and E2 is another
branch or pipe communicating with the intermediate valve F. D¹ is a branch forming
a communication between the belt D and the valve F and F¹ is a pipe communicating
with the branch A¹ of the barrel A. P is a cock or valve to regulate the passage
from F to A. The parts relating to the valves F and E are duplicated as indicated
in the drawing Fig. 1. B' is a small hole forming a communication between the belt D
and the side pipe B the object of which will be subsequently explained. All the
foregoing features will be found clearly set forth in Figure 1.
The firing valve and the mechanism for operating it not forming part of the
present invention do not require to be minutely described but it may be mentioned
that the form of the firing valve shown in these drawings is an annular valve entirely
surrounding the gun tube into which the pressure enters by a number of openings A²
in the tube some of which are shown in the drawings.
I will describe the construction and operation of one of the valves E and F only,
it being understood that the operation of the others corresponds.
The construction of valve F will be understood by reference to Fig. 5 which is
a longitudinal section through the valve and its casing. The valve consists of the
valve proper resting upon a suitable seating and a piston F3 working in the
cylinder or chamber F2 and the arrangement is such that when in its normal
position as shown in Fig. 5 the valve remains closed by reason of the pressure
upon the two sides of the piston F3 being balanced (both the passages D₁ and E²
which open into F2 communicating with the belt D) and the valve being kept
closed by the pressure upon the back of F and also because the pressure through D¹
does not act upon so large an area of the piston as that through E2. When the
valve E is turned to the position shown in Fig. 7 communication is opened between
the space F2 and the atmosphere while that between F2 and the belt D is cut off; the
consequence is that there is merely atmospheric pressure in F2 while on the other side
of the piston F3 is the full pressure of the belt D and the area of the piston upon that
side exceeding the area of the valve proper F4 the valve is opened and retained open
until the normal condition is restored by returning valve E to the position of Fig. 6
when valve F* immediately closes.
The pressure in D is maintained by means of the small hole B¹ which communicates
with the side pipe B which contains the full pressure. The passage of air through
the holes B' inay be controlled by any suitable form of automatic or controlled valve
if desired, but the plain small hole is simpler and may frequently be employed.
without any valve the holes B¹ being too small to cause any undesired rise of pressure
in the gun barrel behind the projectile before the admission of the full pressure.
The operation of the lever of the valve E cuts off the communication between the
belt D and the valve F by the branch E2 and at the same time establishes communi-
cation between the valve F and the atmosphere through the branches E2 and E¹;
this position is shown in Fig. 7. The result of this as previously explained is that
the valve F is opened and immediately establishes communication between the belt D
and the interior of the gun barrel through the branch D¹ the valve F the branch
pipe F and the branch A'. This will admit pressure from the belt D into the
gun barrel behind the projectile M and if the cubical capacity of the space behind
the projectile is equal to the combined capacities of the two belts D the pressure
behind the projectile will be half the pressure which previously existed in the belts D
the pressure in both of which will now have become correspondingly, diminished,
the firing valve C being at this time and indeed always normally closed, so that the
pressure thus admitted cannot escape except by moving the projectile.
The making as above suggested of the capacities of the two belts D equal to
the capacity of the chamber behind the projectile is purely arbitrary and is merely
suggested as a convenient reduction of the pressure from the highest limit at which

page_text: it is intended to discharge the projectile to the lower pressure at which it is desire
to impart to the projectile its initial movement; any other respective capacities an
pressures therefore may be adopted if preferred.
Referring now to Fig. 2, G is the intermediate valve which controls the operation
of the firing valve C. H is a rod or equivalent connected at one end with th
spindle of the intermediate valve G and at the other with the arm I¹ of the latch o
trigger I pivotted at 12 in the gun tube as shown. K is a pawl or detent adapted
to engage the notch I³ when the latch I has been moved or tripped by the pro
jectile so as to prevent its immediate return; this detent K may be controlled in
any convenient manner by the person operating the gun so as to remove it and free
the latch when required and may be assisted in its operation by a spring of any
convenient kind. is a spring for the purpose of normally retaining the latch
in the position shown in Fig. 2. L is a cover for the opening through which the
latch passes and which also serves to carry the detent K and may be bolted on to
the gun barrel in any convenient manner.
The pressure admitted behind the projectile starts it on its course down the barrel A
when it soon reaches the latch I which as shown in Figs. 2 and 3 projects slightly
into the gun tube; as the projectile passes down the barrel the depending end of the
latch I is forced up into the recess provided for it in the metal of the gun tube or
cover L thus turning it upon its pivot 12 and moving the lever I' and consequently
the rod H and valve G. The result of the movement of the valve G is that a series
of operations more or less similar to those described in connection with the valve F
take place, the firing valve C being momentarily opened and automatically closed
again, and the full pressure admitted to the gun tube behind the projectile. (For a
full description of the construction and operation of the valves F, G and C the reader
is referred to the specification of British Patents Nos. 6369 of 1889 and 17185
of 1889. The particular construction of these valves not forming part of the
present invention it is not deemed necessary to labour this specification with details of
their construction beyond the brief explanation given above of the valve F.)
Although I have described the employment of two pressures only, it will be readily
seen that if it be desired to further divide or sub-divide the maximum pressure, that
can readily be done and any required number of pressures admitted behind the pro-
jectile either through the same valve or openings or through different openings
located in different parts of the gun tube any number of latches such as I and connected
mechanism or of ports being then employed.
pressures
The gradual increase of pressure without employing reservoirs at different
or making separate and independent admissions of the propelling agent, may be
accomplished by the means shown in Fig. 8. Here the breech end of the tube is
provided with openings A2 as in Figs. 1 and 2 and these [are surrounded with the
annular valve (also as before. The openings A2 however run to a point A³ at the
ends which are first uncovered on the opening of the valve so that a gradual admission
of the pressure is effected and it will be seen that by properly proportioning and shaping
the openings the full pressure can be delayed until the projectile is well started upon
its.course along the gun tube.
In Figs. 9 and 10 I have shown a pressure gauge Q and a valve for controlling or
closing the hole B'. In the Figs. a spindle M is turned to form a valve or carries
a separate valve at its inner end M' which is adapted to fit the valve seat B2 in the
hole B the spindle M screws into the bush N which screws into the outer wall of
the belt and carries a stuffing box the gland of which makes a tight joint
around the spindle M. By screwing the spindle M in or out the amount of the
opening at B2 can be regulated or closed entirely and therefore if the belt D be
provided with a pressure gauge the pressure in D can be regulated to any portion
of that in the side pipes B that may be desired the valve being closed when the proper
limit has been reached. By this means the initial pressure admitted to the projectile
can be adjusted to whatever may be desired.
If desired valves or cocks P may be inserted in the pipes F¹ between the valves F
and the passages A¹; these cocks would be connected so as to work together as in the

page_text: case of the valves E. In Fig. 1 the lower of these cocks P is shown in section and
partly closed; the upper cock is merely shown in plan. The object of these cocks P
is to control the admission of pressure through the passages A' which cannot be done.
by the valves F which under all circumstances open to their full extent when the
valves E are operated.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I wish it to be understood that I am aware that it has
before now been proposed to increase the pressure in guns after the projectile has been
started on its way down the gun-tube by igniting an explosive gas or powder, and I
therefore make no broad or general claim to such increase of pressure; but so far as
I am aware it has never been proposed to increase the pressure in the barrel behind
the projectile by admitting to the pressure already in the tube and which has pre-
viously started the projectile on its course along the tube, a subsequent charge of the
same air or gas but at a higher pressure or an increased volume of the same air or gas
at the same pressure by giving freer access as in Figure 8. What I do claim is ;-
1. In a pneumatic gun starting the projectile by admitting a relatively low pressure
and afterwards increasing the pressure substantially as described.
2 In a pneumatic gun effecting the gradual increase of pressure upon the projectile
by the admission to the charge of air or gas that has already been admitted at a
lower pressure of a subsequent charge of the same air or gas at a higher pressure
substantially as and for the purpose described.
3. In a pneumatic gun effecting the gradual increase of pressure upon the projectile
by admitting successive charges of air or gas at increasing pressures substantially as
and for the purpose described.
4. In a pneumatic gun effecting the gradual increase of pressure upon the projectile
by a gradual increase in the supply of air or gas at the same pressure substantially as
and for the purpose described.
5. In a pneumatic gun in which increasing pressure is employed for discharging
the projectile the combination with the firing valve or where such are used with the
valve or valves which control the firing valve of an intermediate valve such as F
for the purpose of admitting to the gun tube the initial charge before the
opening of the firing valve substantially as described and illustrated in the accom-
panying drawings.
6. In a pneumatic gun in which increasing pressure is employed for discharging
the projectile the employment in combination with the gun tube of supplemental
reservoirs adapted to be charged from the main reservoirs and to be discharged partly
or wholly independently of the main reservoirs for the purpose of admitting to the
gun tube the low pressure initial charge of low or reduced pressure behind the
projectile substantially as described.
7. In a pneumatic gun in which increasing pressure is employed for discharging the
projectile the combination with the gun barrel A or with one or both of the side pipes B
of one or more belts such as D substantially as and for the purpose described and
illustrated in the accompanying drawings.
8. In a pneumatic gun in which increasing pressure is employed for discharging
the projectile the combination with the supplemental reservoir D and primary
reservoir B of a small hole or passage such as B₁ substantially as and for the
purpose described and illustrated in Figure 1 of the accompanying drawings.
Dated this 17th day of June 1890.
W. P. THOMPSON & BOULT,
Agents for the Applicant.