IMPROVEMENTS IN THE CONSTRUCTION AND MOUNTING OF ORDNANCE
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by James Atkinson Longridge at
the Office of the Commissioners of Patents, with his Petition, on
the 12th June 1875.
I, JAMES ATKINSON LONGRIDGE, of Westminster Chambers, Victoria
Street, in the City of Westminster, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE CONSTRUCTION AND MOUNTING OF
ORDNANCE," to be as follows:
My improvements have for their object,-
First. To avoid the longitudinal tensile strain (arising from the
recoil) on that part of the gun which is between the trunnions and the
breech.
4.
Secondly. To avoid the wear and enlargement of the vent caused
by the corrosive and abrasive action of the gases produced by the
discharge.
In guns as now constructed that part of the gun which is behind the
trunnions is subject to a twofold strain, viz., a circumferential strain
:
1

page_text: tending to tear the gun asunder diametrically, or in other words to Durst
the gun, and a longitudinal strain tending to tear the breech apart from
the trunnions; thus the same metal is at one and the same time sub-
jected to strain in two directions normal to each other.
The object of the first part of my Invention is to relieve the gun of
this longitudinal tensile strain, and cause it to be taken up separately.
In muzzle loading guns this is accomplished by placing the trunnions
at the breech end of the gun.
In some cases these trunnions are furnished with roller wheels, and
the elevating gear is placed in front towards the muzzle end of the gun,
and the gun is mounted on a non-recoiling carriage capable of turning
on a vertical axis, and constructed with curved or inclined ways rising
upwards at the back of the gun for the trunnion rollers to run upon.
The
recoils up
gun
these ways and afterwards descends to its normal
position.
In other cases the gun is mounted on a moveable recoiling carriage,
and there are two sets of trunnions of which the gun trunnions proper
are situate behind the breech as in the former instance, and they are
connected by side rods with a pair of false trunnions which I term the
carriage trunnions. These trunnions are formed on a hoop through
which the chase of the gun passes and in which it rests but without
being attached thereto. The position of these false trunnions corresponds
with the ordinary position of the trunnions of a gun, and they are
mounted in the carriage in the usual way and serve together with the
hoop for the support of the gun, and as the axis on which it moves
when clevated or depressed in the usual way. In this arrangement the
strain of the recoil is transmitted solely through the side rods from the
gun trunnions behind the breech to the carriage trunnions and by
them to the carriage, so that the gun is relieved of all longitudinal
strain.
In breech-loading guns three sets of trunnions are employed, viz.,--
First. A pair of false trunnions on a hoop encircling the chase freely
as before, and serving simply to support the chase and carry its weight.
when the breech is open. I term these the chase trunnions.
Secondly. What I term the carriage trunnions upon which the whole

page_text: weight of the gun is carried, and which are mounted in the checks of
the gun carriage in the ordinary way.
Thirdly. The breech trunnions which support the breech block and
receive the shock of the recoil and transmit it to the carriage trunnions
by side rods. In this case the carriage trunnions are formed on these
side rods, which extend forward to carry the chase trunnions, and
backwards to connect with the breech trunnions. The breech block is
fitted to slide backwards and forwards along the side rods to open and
close the breech chamber of the gun.
gun
When the breech block is drawn back to open the breech the chase is
free and having sufficient preponderance at the muzzle end (when the
is unloaded), the chase tilts on its trunnions, the muzzle dropping,
and the breech rising. At the same time the breech block and side rods
now preponderate over the chase, and the side rods oscillate on the
carriage trunnions so as to depress the breech block and still further
elevate the chase trunnions and the chase, thereby completely enclosing
the breech chamber and bringing it to position for loading. As soon as
the charge is introduced the preponderance of the chase is behind the
chase trunnions, and the chase drops into a line with the side rods, the
breech block is then moved forward to close the breech, and the whole
gun is evenly balanced on the carriage trunnions ready for firing.
One
The sliding breech block may be operated in various ways.
consists in the use of an eccentric on a spindle passing transversely
through the breech block, the ends of said spindle forming the breech
trunnions. This eccentric may either work in a sliding bush fitted to
move vertically in a slot in the breech piece, or the eccentric may work
in a strap in rear of the breech piece and jointed thereto, the sliding
bush being in this case dispensed with.
According to another arrangement the breech trunnion spindle passes
behind instead of through the breech block, and is traversed by a screw
in the line of the axis of the breech block. This screw works in a nut
or female screw, either in the rear of the breech block or in the breech
trunnion spindle, being in either case so arranged as by its action to
move the breech block backward and forward, as required.
Another method consists in employing hydraulic pressure for the
purpose. To this end the breech trunnions are formed on a hydraulic

page_text: cylinder receiving at its front end a ram or plunger formed on the rear
end of the breech block. A screw passes into the cylinder through the
rear end to displace the fluid therein, in order to obtain the pressure
requisite to force forward the breech block to close the breech. The fluid
in the cylinder receives the force of the recoil, and when the screw is
withdrawn a partial vacuum is formed in the cylinder, and the breech
block is forced back by atmospheric pressure.
According to another arrangement the cylinder is divided into two
chambers by a transverse partition of sufficient strength, and having a
small aperture connecting the two chambers. The area of this passage
may be varied or it may be closed altogether.
When the breech block is forced forward to close the breech the fluid
is forced into the foremost chamber where it is retained by closing the
passage until the gun is fired. By a suitable arrangement the passage
is opened at the same moment that the gun is fired, and the fluid is
partly driven back by the force of the recoil into the rear chamber,
whereby the shock of the discharge is lessened.
There are many
methods of operating the breech block of which the foregoing will serve
as examples.
The second part of my Invention relates to a method of igniting the
charge in breech-loading guns without allowing any escape of gases
through the vent, whereby the wear of the vent caused by such escape
is avoided. This is effected by an arrangement whereby a percussion cap
placed on a nipple fixed to the face of the breech block within the
breech chamber is exploded by a blow transmitted by a small internal
cup-headed spring striker mounted in the breech block. The cup head
is detached from the striker and has little or no motion, it being in closo
contact with the percussion cap. It fits tightly on a nipple on the face
of the breech block, and completely encloses the end of the hole through
which the striker works so as to entirely prevent the escape of gas.
The percussion cap nipple is made to turn partly round to enable the
cap to be fitted on it.