AN IMPROVED WATER-PRESSURE ENGINE
Year: 1848

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
GEORGE ARMSTRONG, of the Town and County of the Town of Newcastle-upon-
Tyne, Esquire, Fellow of the Royal Society, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by
Her Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Eleventh day of May, One thousand eight hundred and
forty-eight, in the eleventh year of Her reign, did, for Herself, Her heirs
and successors, give and grant unto me, the said William George Arm-
strong, my exors, adññiors, and assigns, Her special license, full power, sole
privilege and authority, that I, the said William George Armstrong, my exors,
admors, and assigns, or such other as I, the said William George Armstrong,
my exors, admors, or assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term of years therein
expressed, should and lawfully might make, use, exercise, and vend, within
England and Wales, and the Town of Berwick-upon-Tweed, my Invention of
"AN IMPROVED WATER-PRESSURE ENGINE;" in which said Letters Patent is con-
tained a proviso obliging me, the said William George Armstrong, by an
instrument in writing under my haud and seal, particularly to describe and
ascertain the nature of my said Invention, and in what manner the same is to
be performed, and to cause the same to be enrolled in Her Majesty's High
Court of Chancery within six calendar months next and immediately after the
date of the said recited Letters Patent, as in and by the same, reference being
thereunto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
William George Armstrong, do hereby declare that the nature of my said
Invention consists,―
Firstly, in the introduction into a water engine, for the first time, of several
things heretofore well known in steam engines, but never before applied to an
engine deriving its power from the pressure of water; as, for instance, the
placing of the cylinders at right angles with each other, by which arrangement
one crank can be made to serve for both cylinders, as also the inverting of
the usual position of the cylinders in order to economize space;
Secondly, in an improved description of slide valve, by means of which very
spacious water passages may be opened and shut with only a small amount of
friction;
Thirdly, in the application of vulcanized caoutchouc, or other elastic
substance, to overcome some of the difficulties arising in water engines from
the incompressibility of water; and,
Fourthly, in the application of a particular kind of relief valves to give vent
to the water when pent up in the cylinders, and thus to prevent concussion,
and also to prevent the formation of an injurious vacuum, as will be herein-
after explained.
And in further compliance with the said proviso, I, the said William George
Armstrong, do hereby describe the manner in which my said Invention is to be
performed by the following statement thereof, reference being had to the
Drawings annexed, and to the figures and letters marked thereon, similar
letters being used to denote similar parts in each figure of the Drawing.
DESCRIPTION OF THE DRAWINGS.
Figure 1 represents a side view or elevation of the engine; Figure 2 is a
section through the same; Figure 3 is a view of the engine from one end, and
Figure 4 a view of it from the other. A, A, are two cylinders placed at right
angles to each other, and each containing a water-tight piston. B, B, are the
piston rods which each work through a gland on the lower cover of the
cylinder, and are connected with the motion blocks C, C, which slide between
the parallel guides or motion bars D, D, D, D. E is the crank upon the
engine shaft, and F is the fly wheel; G, G, G, are the connecting rods for
communicating motion from the piston rods to the crank. One of these
connecting rods is fork-shaped, having the cylinder contained within the forked
part, as shewn in the Drawings. The other connecting rods consist of single
bars placed one at each side of the cylinder. H, HI, are the eccentrics upon
the main shaft for working the slide valves. Figure 5 is a cross section of the
engine, shewing the valves, valve chests and water passages; J, J, are box

page_text: slide valves which alternately admit and discharge the water to and from the
cylinders through the passages L. L, L, L. K is the escape passage common
to both valves, and M is the supply passage to both valves. In order to
lessen the pressure upon the slides which require to be very large in proportion
to those of a steam engine the back part of each slide is formed of a separate
piece, which rests upon an iron bar or prop N, passing through the escape
passage, and vibrating with the motion of the slides. By this means the
insistent pressure upon the back of each slide is counterpoised by the antagonist
pressure on the other, and thus the friction of the slide in passing over the
parts is very greatly diminished. The back piece of each slide is kept water-
tight by means of a flap of leather, or other suitable material, which overlaps
the joining between the sides and back of each slide. The back piece of the
slide may also be suspended from the back of the valve chest, or the supporting
prop beneath may rest upon a fixed point instead of being sustained by the
pressure on the back of the opposite slide, or the back piece may be mounted
upon àfriction wheels so placed as to roll upon a plane at each side of the slide.
Figure 6 is a section through the water passages L, L, K, M, with what I call
the relief valves in connexion with them; Figure 7 is another section through
the relief valves, and shews how they are connected with the water passages.
The openings O, O, P, Q, Figure 5, correspond with the openings marked by
the same letters in Figures 6 and 7. A set of these relief valves is fixed against
the side of the water passages in connection with each slide valve, and the
chest or case containing one of the sets is seen at R, R, Figure 2. The use
of these relief valves is to supply the want of elasticity in the impelling water,
and their action may be described as follows:-It will be observed that at the
moment when each slide covers the cylinder ports, the piston (in the absence
of the relief valves) would be prevented from continuing its course by the non-
elasticity of the water, without lifting the slide valve from its face, which
would cause not only a great shock upon the engine, but also a considerable
At the same
escape of water from the valve chest into the escape passage.
time also, while the water would be thus locked up on one side of the piston,
its admission would be cut off from the other, so that while the water was
being injuriously expelled on the one side by the progression of the piston, a
void would be left on the other, which would tend to hold back the piston.
Both these evils are remedied by the relief valves in the following manner:-
By tracing the connections of the passages, it will be seen that the clack
valves S and S have the pressure of the impelling column constantly operating
to keep them close, and that the other clacks, namely, T and T, communicate
on the under side with the escape water. It is obvious, therefore, that at those

page_text: points of the stroke, when the egress ports become closed by the slide valves,
and when the pent-up water on the escape side of the pistons would present
an unyielding resistance to the motion of the pistons, the clack valves S, S,
will yield to the superior pressure of the escape water on the under side, and
for an instant allow it to re-enter the supply pipe, thus relieving the engine
from the shock it would otherwise sustain, without involving any sacrifice of
power, inasmuch as the small quantity of water thrust back into the supply
pipe at the expense of the engine acts again upon, the piston on the opening
of the ingress port, and so gives back the power expended upon it. It will
also be observed that the clacks T and T must always rise when the ingress
ports are closed by the slides before the complete termination of the stroke,
and thus the tendency to form a vacuum behind the piston, which would have
the effect of retarding the engine, is avoided. In order still further to soften
the action of the engine, a piece of vulcanized indian rubber, or other elastic
substances, may be fixed on each side of the piston, or at each end of the
interior of the cylinder, or otherwise, in connection with the water spaces at
each end of the cylinder, for by so doing it is obvious that an effect will be
produced equivalent to endowing the water itself with a considerable degree of
compressibility. Figure 8 is another form of slide valve applicable to the
engine; X, X, is the passage for admitting the water to the valve cylinder Y.
This passage is of an annular form, and the water enters the cylinder Y
through apertures in the circumference; U. U, are two slides or pistons
baving the pressure of the water constantly operating between them, and being
consequently in a state of equilibrium; V, V, are annular passages or chambers
communicating with the two ends of the cylinder, and having ports Z, Z, in
the valve cylinder opening unto them; W, W, are the escape passages for
the expended water. Now, as the slides or pistons move up and down, they
alternately open the ports Z, Z, to the pressure and to the escape, and thus the
water is conveyed to and discharged from the cylinders in the same manner as
in the box slide valve; and this arrangement, like the slide valve above
described, has the advantage of opening very spacious passages for the water,
without occasioning a great degree of friction; S¹, S, T, T', are relief valves
which operate upon the same principle as those already described. The slide
valve, Figure 8, may be varied by making W, W, the supply passages, and
X, X, the escape passage; the essential principle of the valve being the balancing
of the two slides or pistons by the pressure of the water in opposite directions
upon them. Figure 9 is a cross section through the middle of Figure 8.
Having now described the nature of my said Invention, and the manner in
which the same is to be performed, I hereby declare that what I claim as my

page_text: Invention, and as constituting my "Improved Water-pressure Engine," is as
follows (that is to say):-
Firstly, I claim the arrangement of the cylinders at an angle to each other
equal to or approaching to a right angle, and the inverted position of them as
applied to a hydraulic engine;
Secondly, I claim the varieties of slide valves herein-before described, and
which are equally applicable as pump valves, especially in cases where the
action of the pump is required to be very rapid ;
Thirdly, I claim the application of what is called vulcanized indian rubber,
or other suitable elastic substances, in hydraulic engines, to compensate for
the non-elasticity of the water, as herein-before described; and
Fourthly, I claim the arrangement of relief valves herein-before described
in Figures 6 and 7, and in part of Figures 8 and 9.
And such my Invention being, to the best of my knowledge and belief,
entirely new, and never before used in that part of Her said Majesty's United
Kingdom of Great Britain and Ireland called England, Her Dominion of
Wales, or Town of Berwick-upon-Tweed, I do hereby declare this to be my
Specification of the said Invention, and that I do verily believe this my said
Specification doth fully, and without reserve or disguise, comply with the pro-
viso in the said herein-before in part recited Letters Patent contained. Where-
fore I do hereby claim to maintain exclusive right and privilege to my said
Invention.
In witness whereof, I, the said William George Armstrong, have here-
unto set my hand and seal, the Ninth day of November, in the year
of our Lord One thousand eight hundred and forty-eight.