IMPROVEMENTS IN THE WORKING OF DISAPPEARING GUNS AND APPARATUS THEREFOR
Year: 1877

page_text: LETTERS PATENT to Alexander Moncrieff, of No. 16, Cromwell Crescent, South
Kensington, in the County of Middlesex, and William Anderson, of No. 3,
Whitehall Place, also in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN THE WORKING OF DISAPPEARING GUNS AND APPARATUS
THEREFOR."
Sealed the 30th November 1877, and dated the 27th August 1877.
PROVISIONAL SPECIFICATION left by the said Alexander Moncrieff and
William Anderson at the Office of the Commissioners of Patents on the 27th
August 1877.
ALEXANDER MONCRIEFF, of No. 16, Cromwell Crescent, South Kensington, in the
County of Middlesex, and WILLIAM ANDERSON, of No. 3, Whitehall Place, also in
the County of Middlesex. "IMPROVEMENTS IN THE WORKING OF DISAPPEARING
GUNS AND APPARATUS THERefor."
In guns which act on what is known as the Moncrieff or disappearing principle_
the recoil causes the gun to sweep backwards and downwards, so that it disappears
behind a parapet or other defence, and this movement is communicated to the
plunger of a hydraulic cylinder, which by making an in stroke forces water from
the cylinder into a vessel containing compressed air, increasing the pressure thereof.
After the gun has been loaded or otherwise handled within the shelter, on opening.
a valve the water under the pressure of the compressed air is permitted to act on
the plunger, causing it to make an out stroke, whereby the gun is raised again to
the firing position.
Our Invention relates to means whereby the recoil and the upward movement
of guns thus worked are automatically retarded and arrested; for this purpose we,
nake the plunger of the hydraulic cylinder in the form of a trunk or differential
piston, presenting its full area on its one side and a small annular area on the other
side. At the inner end or bottom of the cylinder there are escape apertures com-

page_text: municating with the air vessel fitted with check valves, these apertures being
formed in a boss projecting inwards from the cylinder bottom. The under side of
the piston is made with a socket cavity, which fits nearly over this boss when the
piston is at the extreme of its in stroke. Either the boss or the socket is made
tapering, or has tapering channels formed in it. As the piston approaches the end
of its stroke, its sockets fitting nearly over the boss so as to afford very small area
of passage for the water from the socket, the water acts as a cushion, retarding and
, arresting the movement of the piston and the recoil movement of the gun.
The valve, by opening which the gun is raised to its firing position, is in a pipe
or passage leading from the air vessel to an aperture near the mouth of the
hydraulic cylinder. When this valve is opened the water under pressure flows from
the air vessel into the annular space of the cylinder on the one side of the piston
and through holes provided in the piston to its other side, where its pressure, acting
on the full area, causes the piston to make its out stroke, raising the gun. But the
piston as it approaches the extreme of its out stroke covers the supply aperture,
and so stops the inflow of water arresting the upward movement of the gun.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Moncrieff and William Anderson in the Great Seal Patent
Office on the 26th February 1878.
ALEXANDER MONCRIEFF, of No. 16, Cromwell Crescent, South Kensington, in the
County of Middlesex, and William Anderson, of No. 3, Whitehall Place, also in the
County of Middlesex. IMPROVEMENTS IN THE WORKING OF DISAPPEARING GUNS
AND APPARATUS THEREFOR."
In guns which act on what is known as the Moncrieff or disappearing principle
the recoil causes the gun to sweep backwards and downwards, so that it disappears
behind a parapet or other defence, and this movement is communicated to the
plunger of a hydraulic cylinder, which by making an in stroke forces water from
the cylinder into a vessel containing compressed air, increasing the pressure thereof.
After the gun has been loaded or otherwise handled within the shelter, on opening
a valve the water under the pressure of the compressed air is permitted to act on
the plunger, causing it to make an out stroke, whereby the gun is raised again to
the firing position.
Our Invention relates to means whereby the recoil and the upward movement
of guns thus worked are automatically retarded and arrested; for this purpose we
make the plunger of the hydraulic cylinder in the form of a trunk or differential
piston, presenting its full area on its one side and a small annular area on the other
side. At the inner end or bottom of the cylinder there are escape apertures com-
municating with the air vessel fitted with check valves, these apertures being
formed in a boss projecting inwards from the cylinder bottom. The under side of
the piston is made with a socket cavity, which fits nearly over this boss when the
piston is at the extreme of its in stroke. Either the boss or the socket is made
tapering or has tapering channels formed in it. As the piston approaches the end
of its stroke, its socket fitting nearly over the boss, so as to afford very small area

page_text: of passage for the water from the socket, the water acts as a cushion, retarding
and arresting the movement of the piston and the recoil movement of the gun.
The valve, by opening which the gun is raised to its firing position, is in a pipe
or passage leading from the air vessel to an aperture near the mouth of the
hydraulic cylinder. When this valve is opened the water under pressure flows
from the air vessel into the annular space of the cylinder on the one side of the
piston and through holes provided in the piston to its other side, where its pressure
acting on the full area causes the piston to make its out stroke, raising the gun.
But the piston as it approaches the extreme of its out stroke covers the supply
aperture, and so stops the inflow of water, arresting the upward movement of the
gun.
Fig. 1 of the accompanying Drawings represents a longitudinal section, and
Fig. 2 a transverse section of the hydraulic cylinder and air vessel for a disappearing
pivot gun, the cylinder being in this case arranged in a horizontal position.
A is the cylinder partly enclosed within the air vessel B, which is firmly fixed
within the framework C of the gun carriage; D is the plunger, which has a ring or
collar d fixed near its inner end, leaving a few small passages e from the one side
of the collar to the other. The plunger terminates with a socket cavity, which,
when the plunger is home, embraces a hollow boss F projecting from the cylinder
bottom. This boss is made taper, or has tapering grooves cut along its sides, and
is perforated with a number of holes f near its base. From the interior of the boss
there is the discharge aperture leading into the air vessel, and fitted with a check
valve G pressed to its seat by a spring adjustable by a screw g, to which access is
given by a hole at the end of the air vessel closed by a removeable cover g¹. In this
cover is a hole closed by a screw plug and having an internal check valve, which
hole is used for preliminary charging of the air vessel with compressed air. From
the lower part of the air vessel, in which part there is always water, a passage H,
fitted with a screw valve h, leads to a pipe I, which extends to the front end of the
hydraulic cylinder A and has an opening into it, i, of a taper form, as shewn in
the plan, Fig. 3.
The outer end of the plunger K being connected in the usual way to the moving
framework of the gun, the action is as follows:--The gun being down in its lowest
position, the air vessel being in its upper part charged with compressed air and
baving water in its lower part, the valve his withdrawn from its seating by
turning the nut on its screwed stem. Water under pressure is thus admitted to
the pipe I, along which it flows, and whence it passes by the mouth i into the
annular space of the cylinder A in front of the collar d. From this annular space
it passes by the apertures e to the space at the inner end of the cylinder, and
pressing there on the full area of the plunger D forces the plunger outwards,
thereby raising the gun towards the firing position. As the plunger approaches
the end of its out stroke the collar d passes over the opening i, gradually closing
it, and thus the outward movement of the plunger and the ascent of the gun are
retarded and arrested. The gun having been raised the valve h is closed, and the
gun is retained in firing position. When the gun is fired the recoil causes the
plunger D to make its in, stroke, forcing the water by the valve opening G back
into the air vessel. As the plunger approaches the end of its in stroke its socket .
end embraces the projecting boss F, gradually checking the flow of water from the
space within the socket, and this retardation of the escape of the water produces a
back pressure on the end of the plunger which gradually retards and finally arrests
the inward movement of the plunger and the descent of the gun.
Having thus described the nature of our Invention, and in what manner the
same is to be performed, we claim as improvements in disappearing heavy guns
worked hydro-pneumatically,-
First. Constructing the base of the hydraulic cylinder with an inwardly pro-
jecting boss and the base of the recoil plunger with a corresponding socket cavity,
giving restricted passage as the plunger approaches the end of its instroke, so that

page_text: the escape of water from the cylinder is throttled and the recoil of the gun is
thereby automatically retarded and arrested, substantially as herein described.
Second. Arranging the supply inlet to the hydraulic cylinder near its outer end,
and making the recoil plunger of differential area, by providing at its base a collar,
which, as the plunger approaches the end of its outstroke, covers the inlet, thereby
causing the upward movement of the gun to be automatically retarded and arrested,
substantially as herein described.
In witness whereof, I, the said Alexander Moncrieff, have hereunto set my
hand and seal, this Twenty-fifth day of February, in the year of our Lord
One thousand eight hundred and seventy-eight.