Year: 1887

page_text: Date of Application, 11th May, 1887
Complete Left, 11th Feb., 1888
Complete Accepted, 16th Mar. 1888
I JAMES ATKINSON LONGRIDGE of 15 Great George Street in the City of
Westminster, Civil Engineer do hereby declare the nature of this invention to be
as follows:
This Invention relates to what are known as disappearing and also to non-
disappearing guns; and it has for its object to enable the energy of recoil to be.
absorbed or stored in such a way as to relieve the carriage of the sudden strain, and
in the case of a disappearing gun, to be utilized in raising the gun again to firing
position.
The reinforced part of the chase is made of cylindrical form externally, with a
shoulder at the front end which is fitted to slide and act as a piston in an outer
cylinder, the breech end of the gun sliding in the manner of a piston rod through a
gland at the rear end thereof. The gun itself has no trunnions and is free to slide
Backward and forward in the line of its axis in the cylinder which is supported by
trunnions in a swivelling forked bearing, whereby the necessary motions of the gun
in altitude and azimuth are obtained. The annular space between the gun and the
cylinder, communicates through one or both trunnions with an air compressing
cylinder or with a simple air vessel, according as the gun is or is not to disappear.
In the former case, the swivelling trunnion bearing turns on its vertical axis in, and
is supported by a shoulder or disc upon a trunk terminating at its lower end in a
piston which works in a fixed vertical cylinder, the trunk sliding through a gland
in the head of the said cylinder and being guided in its vertical motion by a fixed
pillar or frame. The annular space between the gun and cylinder communicates
(through the trunnion, the swivelling trunnion fork, its vertical axis, and the piston
at the lower end of the trunk) with the annular space at the upper side of said piston,
all of said spaces being filled with liquid, while the lower end of the cylinder is
closed and is filled with air compressed to a sufficient initial pressure to raise the
trunk, and consequently the gun, to its highest position and force the gun forward
in its cylinder. The energy of the recoil forces the gun to slide back in its cylinder,
thereby driving out the liquid into the upper end of the air compressing cylinder,
forcing down the piston and trunk, lowering the gun, and compressing the air in the

page_text: lower end of said cylinder. Suitable valves are provided for preventing the return of
the water, and permitting the gun to remain in its lowered position whilst being
reloaded, and the energy so stored, is kept available for raising the gun again and
returning it to its normal or firing position.
In the case of a non-disappearing gun, the space between the gun and its cylinder,
communicates as before through the trunnion and vertical swivelling axis, with a
pipe dipping into an air vessel. In this case, the compression of the air merely
serves as a buffer to absorb the recoil, the re-expansion of the air immediately
forcing the gun forward again in its cylinder. The trunnion bearing may either
be supported on suitable legs or standards, or it may form part of the ordinary
recoiling carriage. In some cases, instead of trunnions I may form the outer
cylinder with a spherical boss whose centre is coincident with the axis of the gun
and which is embraced by, and is supported and free to swivel in all directions in,
a corresponding spherical cup socket in the manner of a ball and socket joint.
I do not limit myself to the use of air-compression, as a medium for absorbing
and storing the energy of recoil, but may cause the hydraulic pressure to act on a
combination of springs or other elastic medium.
Dated this 11th da
M1007
J. A. LONGRIDGE.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.

page_text: COMPLETE SPECIFICATION.
Improved Means of Absorbing and Utilising the Recoil of Guns.
I, JAMES ATKINSON LONGRIDGE of 15, Great George Street, in the City of
Westminster, Civil Engineer, 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 "disappearing" and also to "non-disappearing" guns;
and it has for its object to enable the energy of recoil to be gradually absorbed or
stored so as to relieve the carriage of the sudden strain, and to be utilized (in the
case of a disappearing gun) in raising the gun again to firing position. These
objects are accomplished by so mounting the gun as to permit of its recoiling quite
independently of the carriage or mounting and by causing the energy of recoil of the
gun to be transmitted, through a liquid medium acted on directly or indirectly by
the gun itself, to a compressible fluid contained in a closed chamber, or to springs
or other elastic medium by which the said energy will be absorbed gradually and
given out again at the required moment for returning the gun to the firing
position.
My Invention comprises also the several arrangements of mechanism or means
whereby these results may be accomplished, and which I will proceed to describe in
detail with reference to the accompanying drawings forming part of this specification;
wherein Figure 1 is a vertical longitudinal section of the mounting of a non-
disappearing gun; Figure 2 is a horizontal section, and figure 3 a transverse section,
through the trunnion axis the latter figure showing on the right hand side an
alternative means of making the hydraulic connection between the trunnion and the
mounting, which is not shown in figure 2; Figures 4 and 5 represent details ;
Figure 6 represents a modification, wherein springs are employed instead of air, for
storing up the energy of recoil; Figure 7 is a side elevation; figure 8 a horizontal,
and figure 9 a transverse section, through the trunnions of a non-disappearing gun
in which the gun acts indirectly on the hydraulic medium; Figure 10 is a vertical
section of the mounting of a disappearing or barbette gun, Figure 11 is a detail
thereof; Figure 12 is an elevation of another arrangement of the mounting of a
disappearing or barbette gun; Figure 13 is a part plan of the mounting; and
Figures 14 and 15 are sectional elevations of modifications of the arrangement of
air vessel which may be used for absorbing the energy of recoil in the case of the
disappearing or barbette guns illustrated in the previous figures.
In all the figures, the same letters of reference indicate corresponding parts.
Referring now to figures 1 to 5, which illustrate a non-disappearing gun acting
directly on the hydraulic medium by which the energy of recoil is transmitted to
the absorbing and storing medium; the reinforced part A of the chase of the gun is
made of cylindrical form externally and has a shoulder a forged, cast, or otherwise
firmly fixed on it, at the front end of the cylindrical part of the gun, which shoulder a
s fitted to slide and act as a piston in an outer cylinder B (hereafter termed the gun
ylinder) the breech end of the gun sliding in the manner of a piston rod through a
gland and stuffing-box or cup leather b at the rear end of the gun cylinder B. The

page_text: gun itself has no trunnions, and is free to slide backward and forward in the line of
its axis in the gun cylinder B which is of a proper length to permit of the amount of
recoil to be provided for, and is supported by trunnions C in bearings on a forked
mounting D E which swivels on a vertical axis in a stationary frame F, whereby the
necessary motions of the gun in altitude and azimuth are permitted.
The annular space G between the cylindrical part A of the gun and the cylinder B,
communicates, through one or more ports or passages g leading from the rear end
of the space G through one or both trunnions C, with passages d in the forked
mounting D which passages in turn communicate with a pipe e dipping into a closed
air chamber E¹ formed within the vertical or axial part E of the mounting. The
connection of the trunnion passages with the passages d may either be as shown at
the left hand side of figure 3, provision being made (by making the entrance to the
passaged in the trunnion bearing oblong) for maintaining the connection when the
gun is elevated or depressed; or the connection may be by means of an outside pipe
and stuffing boxes, as shewn at the right of same figure. The part E may either be
made solid with the forked bearing D, as shewn, or bolted to it. It terminates at foot in
a pivot e¹ resting in a footstep bearing of the fixed frame, and has a shoulder at the
upper part, fitting in a gun metal collar bearing f" carried by the frame F which
may be of any convenient construction but is shewn as a frustrum of a hollow cone
flanged at top and bottom. The footstep bearing supports all or most of the weight
of the gun mounting, and in these bearings the gun is free to be trained or rotated
in azimuth. The space G between the gun and its cylinder and all the ports and
passages, are filled with water, oil, or glycerine, which rises in the chamber E¹ just
above the mouth of the pipe e. Air is then forced into the air chamber to such a
pressure as to at least equal the friction of the gun in the cylinder B, or to such
greater pressure as may be required.
When the gun is fired, it recoils longitudinally in the cylinder B, the shoulder a
driving the liquid therein out through the passages into the chamber E', further
compressing the air therein by which the energy of recoil is stored up to be expended
in returning the gun to its normal position. When required, a check valve opening
downwards may be placed at the top of the pipe e to prevent the return of the liquid
until the required moment. Such a valve is shown at h in figure 6.
If it be desired to reduce the length of recoil of the gun and also to equalize to
some extent the pressure in the gun cylinder B, an obturating pieco gl is fixed to the
gun A so as to work in the manner of a slide valve over each port 9 (represented by
dotted lines in figure 5) said piece being of such a curved or tapering form as to, at
first, fully open and then gradually close the port 9 in such manner that the escape of
the liquid may be so controlled as to render the resistance through the recoil of the
gun as nearly uniform as may be desirable. As the velocity of recoil is nil at starting,
but increases very rapidly at first, the curve of the obturating piece falls suddenly,
and after the maximum velocity of recoil has been attained it rises gradually, so as
to gradually reduce the area of the port, and render the resistance uniform, or
nearly so.
Referring now to figures 7, 8, and 9, the gun A. fits closely in the jacket cylinder B
throughout its length, the shoulder a being dispensed with and the annular chamber G
between the gun and its cylinder being replaced by twin cylinders G G, placed one
at each side of, and parallel with, the cylinder B and cast in one therewith or bolted
thereto, the whole being provided with hollow trunnions which rest on the carriage
or mounting and communicate with the air vessel, as before described. The two side
cylinders Gare provided with pistons & whose rods pass through stuffing boxes at the
rear ends of the cylinders and are connected to lugs at the breech end of the gun.
The cylinders G communicate by ports g at their rear ends, with the hollow
trunnions through which the liquid is expelled by the pistons bas by the shoulder a
in the former case, so that the jacket cylinder is relieved of longitudinal strain
of recoil.
Figure 6 represents an arrangement wherein springs are used, instead of air, for
storing up the energy of recoil. In this case, the air cylinder E of figures 1 and 3,

page_text: is replaced by a cylinder H fitted with a hollow plunger or ram h passing through a
stuffing box or cup leather at the lower end of the cylinder. Between the inner end
of the plunger h and a bridle H¹ attached to the cylinder H are interposed a series of
springs I, such as that known as the Belleville spring. The upper end of the cylinder H
communicates with the passages d in the forked trunnion bearing, as before, and a
check valve h' is applied at the point of communication with said passages, to prevent
the return of the liquid until the required moment after recoil, as before mentioned,
and which may or may not be used as preferred. The liquid forced out of the annular
chamber G or lateral cylinders G as above mentioned, presses on the ram h and
forces it down, thus compressing the springs I and storing up the energy of recoil.
When it is desired to return the gun to its firing position the check valve is opened
by suitable arrangements which need not be described.
In this arrangement, the cylinder H is part of the fixed frame on which the
trunnion mounting rests and turns, this horizontal rotation being provided for by
a set of rollers running on a circular roller path.
In figure 10 which represents one arrangement of mounting for a disappearing
gun the arrangement and operation of the gun within its hydraulic jacket cylinder
and forked trunnion mounting are similar to that already described in respect of the
non-disappearing gun shewn in figures 1 to 5, and need not again be described.
In this case, the vertical member E of the gun mounting is the trunk of a piston K
which works in an air compressing cylinder L; or other arrangements may be
adopted for connecting the piston K with the mounting D, so that the two will
descend together. The trunk slides through a gland in the head of the said
cylinder L and is guided in its vertical motion by a fixed frame. The annular space
between the gun and its jacket cylinder B communicates as before (through the
trunnion, the swivelling trunnion fork, the pipe e, and passages in the piston K)
with the annular space at the upper side of said piston, all of said spaces being filled
with liquid. The lower end of the cylinder L is closed and it is filled with air
compressed to a sufficient initial pressure to raise the movable part of the gun
mounting, and consequently the gun to its highest position and force the gun forward
in its jacket cylinder. The energy of the recoil forces the gun to slide back in its
cylinder, thereby driving out the liquid in the annular space above the piston K
in the air compressing cylinder, forcing down the piston and trunk, lowering the gun,
and compressing the air in the cylinder L. A check valve is provided, as shewn in
figure 11, for preventing the return of the water and permitting the gun to remain
in its lowered position whilst being reloaded and the energy so stored is kept available
for raising the gun again and returning it to its normal or firing position. If the
trunk E be also the axis on which the gun rotates in azimuth it would of course be
cylindrical, and this rotation may be effected by means of a spur wheel M whose boss
turns in the fixed frame and through which the trunk is free to slide with a groove
and feather connection by which the two are turned together for the purpose of
training the gun. The trunk E may be in one or more parts, and the trunnion
bearings may rotate independently thereof in training the gun. Such an arrangement
is represented in figure 11 in which the trunnion bearings rotate on rollers running
between roller paths, as in figure 6.
Referring now to figures 12 and 13, the descending portion of the mounting rests
upon a platform carried by a plate girder frame N, which extends across the gun
pit or turret and abuts against a metallic cylinder or lining 0 of the gun pit or turret.
The frame N rests on rollers n which run on a racer formed by a circular girder P
which extends around the pit or turret and rests upon rams R working in hydraulic
cylinders which are all in open connection with a common reservoir in which a
sufficient pressure is maintained to counterbalance the weight of the descending
parts of the gun and mounting, or so much thereof as may be desirable. The capacity
of this reservoir relatively to that of the ram cylinders should be so great that the
expulsion of liquid from the latter on the descent will not cause the pressure to vary
materially. The circular girder P and rams R are guided in their up and down
motion, by vertical guides fixed to the sides of the pit or turret. In training the gun,

page_text: the bridge girder frame N turns with it upon the racer P, so that the girders N
always remain parallel to the gun axis, and by their ends abutting against the sides
of the pit or turret the trunk E is relieved of all horizontal strain. The trunk E
terminates in a piston working in an air compressing cylinder and operated by the
hydraulic pressure from the gun jacket cylinder, as described in reference to
Figure 10; but if preferred the springs shewn in Figure 6, or other equivalent
arrangement, may be adopted.
In some cases, instead of compressing the air in the cylinder L, this is done in a
separate air vessel, as shewn in figure; 14 and 15, in which the cylinder L is filled
with liquid and is connected at bottom with the lower part of an air vessel S into
which the liquid will be driven by the descent of the piston K compressing the air in
the vessel S. In this case, the means described in reference to figures 4 and 5,
whereby the resistance to the recoil is made uniform by varying the discharge
aperture of the liquid, may be applied to some other part of the mechanism, for
instance to the passage connecting cylinder L and air vessels S, as shewn in figure 15,
in which T is an obturating valve working in a cylinder through which the liquid
must pass from L to S, the valve T being operated by being connected to some part of
the descending mechanism, and being so formed and adjusted in relation to the
passages, as to first open the latter fully and then close them gradually.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I would observe that I
do not limit myself to the particular arrangements described, but that what I
claim is;
1st. The herein described mode of mounting, and transmitting the energy of
recoil of, a gun, whereby the gun alone is permitted to recoil independently of all
other parts of its carriage or mounting, and whereby the energy of recoil is transmitted
to an elastic medium to be thereby stored up through a liquid acted on directly or
indirectly by the gun, as herein described.
2nd. The construction and arrangement of gun and mounting shewn in figures 1
to 6, wherein the gun in its recoil acts as a piston within a jacket cylinder provided
with trunnions and with passages communicating through the trunnions with an air
vessel or with the cylinder of a ram acting on springs the jacket cylinder and passages
being filled with liquid acted on directly by the gun, as and for the purpose specified.
3rd. The construction and arrangement of gun and mounting shown in figures 7 to 9,
wherein the gun slides in a guide cylinder and has pistons attached acting in
cylinders parallel to the axis of the gun whereby the energy of recoil is transmitted
through a liquid passing through the trunnions to an elastic medium, as and for the
purpose specified.
4th. The herein described mode of, and arrangements for, mounting a gun and
transinitting its energy of recoil through a liquid to an elastic medium to be thereby
stored up for subsequent utilization, and of at same time causing the said energy of
recoil to draw the gun and its carriago or mounting vertically downwards, as
specified.