IMPROVEMENTS IN GUN CARRIAGES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Josiah Vavasseur at the Office of the
Commissioners of Patents on the 16th April 1881.
JOSIAH VAVASSEUR, London Ordnance Works, Bear Lane, Southwark, in the
County of Surrey, Engineer. "IMPROVEMENTS IN GUN CARRIAGES."
These improvements refer to those gun carriages which are mounted on slides,
and consist, first, in an improved arrangement of rollers on which the gun carriage
runs during recoil and while running out; and, secondly, in an improved elevating
gear for the gun.
In the method of construction hitherto adopted for gun carriages mounted on
slides and always supported on rollers, the latter are fixed to the carriage itself, in
consequence of which the height from the top of the slide to the centre of the
trunnions of the gun is greater than would be necessary if there were no rollers.
The increased height requires increased length in order to give the necessary
stability, and the weight of the carriage is thereby increased." In my improved
arrangement the carriage is made without, rollers, the bottoms of the carriage
cheeks are planed so as to run on the upper parts of the peripheries of rollers
sufficiently numerous, suitably fixed in the girders forming the slide. Thus the
height from the base to the centre of the trunnion bearings, and consequently
the length and weight of the carriage, can be reduced to a minimum consistent
with strength.
In some cases I arrange that the carriage at the instant of firing shall bear for a
certain portion of the length of its base on the upper surface of the slide girders
and not entirely on the rollers, the carriage going more and more on the rollers as
it recoils.
My improved elevating gear is applicable to those gun carriages mounted on
slides where the gun is supported in fixed trunnion bearings, and consists in an
arrangement whereby the gun is always brought to one position at its maximum
recoil. I find the most convenient position is that of greatest depression, this
being suitable for loading a breech loading gun; and the raising of the breech during
recoil and consequent lowering of the muzzle also allows of some reduction being
made in the height of the port, should the gun be mounted in a ship or in a
casemate.

page_text: The
The fittings on the gun consist of a hoop shrunk or otherwise secured on the
breech with lugs on either side at its lower part, to which is bolted or otherwise
fixed a transverse bar extending from lug to lug and having pins formed at the
ends, the pin at one end carrying a roller, and the pin at the other end carrying a
sliding block. The fittings on the slide consist of a solid planed bar inclined
upwards to the rear, fixed to the inner face of and terminating near the rear end of
Fixed to the inner
the slide girder on that side where the gun carries the roller.
and opposite face of the other girder is a grooved bar inclined upwards to the rear
at the same inclination as the solid planed bar, and also terminating near the rear
end of the slide girder. The grooved bar supports an elevating slide having its
upper surface parallel with the top of the slide girders, which can be moved along
the grooved bar by means of a screw placed at the bottom of the grooved bar
working in a nut in the elevating slide. The screw is turned by a hand wheel at
the rear of the slide girder or by other suitable gear. I prefer the gun having
sufficient breech preponderance so that it may, without it being necessary to use
any mechanical means, tend constantly downwards; the short sliding block carried
by the elevating hoop will thus always bear on the top of the elevating slide
carried by the grooved bar at all times when the gun is in firing position.
inclination given to the bars is such that when the elevating slide is at the position
of greatest elevation of the gun, the slide block on the gun bears on the rear part of
the elevating slide, and when at the position of greatest depression the slide
block bear on the forward part of the elevating slide. Elevation is given to the
gun by moving the elevating slide along the grooved bar by means of the screw,
and the elevation of the gun will remain constant for successive rounds so long as
the position of the elevating slide is unchanged. When the gun is fired at its
maximum elevation it will recoil for a short distance with the block bearing in the
elevating slide, which, being parallel with the top of the slide girders, will not
alter the angle of elevation; but as the motion continues the block will pass off the
elevating slide on to the top of the grooved bar, and at the same time the roller on
the opposite side will bear and run on the solid bar, and thus during the remaining
motion of recoil the breech of the gun will be raised until it finally comes to rest
at the position of maximum depression. When fired at its maximum depression
the gun recoils parallel with the top of the slide girders, and the block runs back
for the whole length of recoil on the elevating slidė; in this case the breech of the
gun has not to be lifted and the roller does not come into play. At intermediate
angles of elevation, as. the gun recoils the block first runs for a certain distance,
increasing as the angle of elevation diminishes on the elevating slide, and for the
rest of its course the block and also the roller run on their respective inclined
bars so that at the end of recoil the breech of the gun is always brought to the
same position.