IMPROVEMENTS IN STEAM ENGINES
Year: 1855

page_text: LETTERS PATENT to Edward Ellis Allen, of 376, Strand, in the County
of Middlesex, Engineer, for. the Invention of "IMPROVEMENTS IN STEAM
ENGINES."
.Sealed the 15th October 1855, and dated the 17th April 1855.
PROVISIONAL SPECIFICATION left by the said Edward Ellis Allen at the
Office of the Commissioners of, Patents, with his Petition, on the 17th
April 1855.
I, EDWARD ELLIS ALLEN, of 376, Strand, in the County of Middlesex,
Engineer, do hereby declare the nature of the Invention for "IMPROVEMENTS
IN STEAM ENGINES" to be as follows:-
This Invention has for its object improvements in the arrangement .and
-construction of steam engines, with a view to employ steam expansively with
more convenience and advantage than heretofore, and is more particularly
applicable for marine engines to give motion to screw or submerged propellers.
For this purpose, in constructing a steam engine I connect the trunks of the
pistons of two steam cylinders together, in such manner that the two pistons
may move together. The steam passages to and between the two steam
cylinders are arranged in the following manner-High-pressure steam is
admitted alternately to the two steam cylinders in such manner as to act only
whilst at full pressure on the smaller area of the piston, and for a part only of
the stroke which is completed by the expanding of the steam; a passage is then
opened to the other end of the cylinder, in order that the expanding steam
may act on the larger area of the piston as well as on the smaller area, first

page_text: mentioned, the larger area of the piston being open to a vacuum when steam
is admitted to the other side; or the expanding steam may in some cases be
conducted to the larger area of another piston in a different steam cylinder.
Another part of my Invention consists of making the cylinder of a trunk
engine double, or of two diameters, so as to have two pistons on the same
trunk, one to work in the smaller part of the steam cylinder, and the other
piston to work in the other or larger portion of the steam cylinder. The spaco
intermediate of the two pistons in such cases is kept constantly vacuous by
being open to the condenser. The steam passages in this arrangement are
such that high-pressure steam is admitted to the smaller part of the steam
cylinder at the time that the larger part of the cylinder is open to the condenser.
Motion is communicated from the interior of the trunk to the crank in the
usual manner of trunk engines. The trunks of two of these steam cylinders
'may be combined together, as above described; or, in place of having the space
"between the two pistons vacuous, a partition may be placed across, so as to
divide the larger cylinder from the smaller cylinder, and a tubular passage is
formed through the larger cylinder for the passage of the trunk. In this
arrangement the larger piston would be a ring piston, not directly fixed to the
trunk, but connected therewith externally of the cylinder by two piston rods.
In this arrangement there would be four steam spaces, two for steam from the
boiler, and two for the steam to expand into. In some cases I do not use
trunks when forming steam engines to be worked by steam expansively, where
the steam cylinder or cylinders are each composed of two diameters, a larger
and a smaller one, in which case the two pistons are connected by one piston
rod; the larger piston having two piston rods passing through the back cover
of the larger part of the steam cylinder, and giving motion to the shaft by two
connecting rods, or the two piston rods of the larger piston may pass through
the front end cover of the larger part of the steam cylinder, and by one con-
necting rod give motion to the shaft, the crank of which in such arrangement
would be conveniently between the two piston rods.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Edward Ellis Allen in the Great Seal Patent Office on the
17th October 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
ELLIS ALLEN, of 376, Strand, in the County of Middlesex, Engineer, send a
greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventeenth day of April, in the year of our. Lord
One thousand eight hundred and fifty-five, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Edward Ellis Allen, Her special licence, that I, the said Edward Ellis
Allen, my executors, administrators, and assigns, or such others as I, the said
Edward Ellis Allen, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
STEAM ENGINES," upon the condition (amongst others) that I, the said Edward
Ellis Allen, by an instrument in writing under my hand and seal, should par-
ticularly describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed, and cause the same to be filed in
the Great Seal Patent Office within six calendar months next and immediately
after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Edward Ellis Allen, do hereby declare
the nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof (that is to say) :-
My improvements consist in the arrangement and construction of steam
engines, with a view to employ steam expansively with more convenience and
advantage than hitherto, or by certain combinations of parts of steam engines
to work with greater uniformity of action, although the steam may not be more
expansively employed than usual. These improvements are more particularly
applicable to marine engines, although their use is not necessarily confined to
engines of this class.
First, in Figure 1, I connect the trunks D, E, of the pistons of two steam
cylinders B, F, in such manner that the two pistons move together. The
steam passages to and between the two steam cylinders are arranged in the
following manner :-High-pressure steam is admitted alternately to the two
steam cylinders in such manner as to act only whilst at full pressure on the
smaller area of the piston A, A, during the whole or for a part only of the
stroke, in which latter case the stroke is completed by the expanding of
the steam. A passage is then opened to the other end of the cylinder B, in
order that the steam may act on the larger area of the piston as well as on the
smaller area, first mentioned, the larger area of the piston being open to the
condenser when steam is admitted to the other side; or the expanding steam

page_text: may, if desired, be admitted into a different larger cylinder. It is preferred to
employ two or more pairs of cylinders, such as are shewn in Figure 1, and
when two pairs are employed; their trunks are to be connected to the shaft or
axis by cranks at right angles to cach other.
The arrangement and disposition of air pumps and condensers may be as
desired, they in the arrangement above described forming no part of my
improvements. When two cylinders only are used, and it is desired to couple
them at right angles, I connect the trunk D of one steam cylinder. B with
another trunk E, as in Figure 2, or with a piston E, as in Figure 3; such trunk
or piston being open to the condenser, and therefore relieved of the atmospheric
pressure on one side. If a piston be used it is made to work in a cylinder G
fixed in the condenser, as shown in Figure 3. In some cases this cylinder may
serve as an air pump, valves being arranged at V, V. In this arrangement the
connecting rod may be jointed to the piston, as being, perhaps, more convenient
than when attached to the trunk. When four piston rods H, H, are employed,
and the fixed cylinder G used as an air pump, the size of it may be sometimes
conveniently reduced, and the piston worked by two rods only, the remaining.
two being used to work the feed and bilge pumps, as shewn in Figure 8ª;
also the trunk in Figure 2 may work in a fixed cylinder, and so form the
plunger of the air pump. The fixed cylinder in this case also may be reduced
in size, and the trunk worked by two rods only, the remaining two rods being.
used to work the feed and bilge pumps, as shewn in Figure 3. A modification
of this arrangement is shewn in Figure 4. Where oue cylinder is used for high.
pressure and the other for expansion, I do away with one of the trunks, and
connect the trunk D of one cylinder B with an ordinary piston E in the oppo-
site cylinder F by means of two or more piston rods H, H, passed through the,
cover of the cylinder F, as shewn in Figure 4. The trunk may either work in
the high-pressure or in the expanding cylinder, as shewn. The trunk in this
arrangement would be as small as possible, and the atmospheric pressure
balanced by regulating the admission of steam on the opposite sides of the
pistons. This arrangement also conveniently admits of the use of a trunk on
both sides of one of the pistons, as in Messieurs Penn's Patent, or it may be
guided by a rod passed out at the back of the cylinder. Although the various
forms of engines above described may be called double expansive engines, I do
not confine myself so to use them, as the arrangements described may be
modified, and the valves worked so as to admit steam direct from the boiler.on
both sides of the pistons.
Another part of my improvements consists in making the cylinder of a trunk
engine compound, or of two diameters, as shewn in Figure 5, so as to have two

page_text: pistons on the same trunk, one to work in the smaller part A of the steam
cylinder, and the other piston to work in the larger part B of the steam cylinder.
The space G, G, intermediate of the two pistons in such cases is kept con
stantly vacuous by being open to the condenser. The steam passages in this
arrangement are such that high-pressure steam is admitted to the smaller part
of the steam cylinder at the time that the larger part of the cylinder is open,
to the condenser; the steam is then passed from the smaller to the larger,
end of the cylinder, and there expands. Motion is communicated from the
interior of the trunk to the crank in the usual manner of trunk engines. The
trunks of two compound steam cylinders may be combined together in the
manner shewn, or the trunk of one compound cylinder may be connected with
an opposite trunk or piston, in the manner above described with reference to
Figures 2 and 3; all these plans with compound cylinders; being. for double,
expansion.
.
Another part of my Invention consists in constructing a cylinder of two
diameters, as above described, but having a partition across, so as to form a
double cylinder, as shewn in Figure 6, or the two parts may be cast separately
and bolted together. In this construction a tubular passage is formed through;
one of the parts for the passage of a trunk or piston rod; and one of the pistons.
is made a ring piston, not directly fixed to the trunk or piston rod of the other
piston, but connected therewith externally of the cylinder by two or more piston
rods, as shewn in Figures 6 and 7. In this arrangement tliere would be four
steam spaces, two for the steam from the boiler, and two for the steam to
expand into. The atmospheric pressure on the trunk. in Figure 6 may. be
balanced by regulating the admission of steam, or the trunk may be combined
with an opposite trunk or piston, as above described. Motion may be given to
the shaft; in the arrangement shewn in Figure 7, by having four rods attached.
to the cross head, which may be united at their ends to a guide block, to which.
the connecting rod may be attached by a joint. This guide block may be of
any convenient form, and worked in an opening formed in the condenser, if
the condenser be placed opposite to the cylinder, the opening in the, condenser
in such case being made large enough for the vibration of the connecting rod.
This arrangement is shewn in Figure 7, and the air pump is shewn wo
worked
from the lower piston rod.
In constructing double expansive engines where the cylinders are compound,
or of-two diameters, as described above, and shewn in Figure 5; I do not always
employ a trunk, but I connect the two pistons together by one, or more-piston
rods, as shewn in Figure 8, and pass two piston rods from the large piston out
of the back cover of the larger part of the cylinder, guiding them in any con-

page_text: venient manner, and give motion to the crank shaft by two connecting rods, as
shewn; or I pass the two or more piston rods from the large piston out of the
front end cover of the larger part of the cylinder, and by one connecting rod
give motion to the shaft, as in Figure 9. The two or more piston rods in this
latter arrangement are prolonged beyond the shaft, and then united in any
convenient manner, as by a cross head, and from which cross head I extend
two or more guide rols or bars which have their ends guided, and to which
one end of the connecting rod is jointed, the connecting rod being carried back
to the crank, as shewn, and working between the said rods or bars; or the cross
head and guide rods or bars may be formed by two T pieces, as shewn. The
guide or guides for the ends of these rods or bars may be formed in the con-
denser when it is placed opposite the cylinder, and the air pump may be
conveniently placed in such condenser, and worked horizontally from a rod
made in continuation of the lower piston rod, as shown.
.
Having thus described the nature of my said Invention, and the manner
of performing the same, I would have it understood that I do not confine
myself to the details herein described, nor do I claim any of the mechanical
parts separately; but what I claim is,―
First, the combination of the trunk of the piston of a steam cylinder with an
opposite trunk or piston, as described.
Second, I claim the use of a trunk when employed in a compound or double-
cylinder engine, whether such trunk be combined with another opposite trunk
or piston, or not.
Third, I claim the construction of a double-cylinder engine in the manner in
respect to Figures 6 and 7.
Fourth, I claim the construction of a compound cylinder engine in the
manners described, that is, with double connecting rods, as in Figure 8, or with
single connecting rod and double guide rods, as in Figure 9.
In witness whereof, I, the said Edward Ellis Allen, have hereunto set
my hand and seal, this Seventeenth day of October, in the year of
our Lord One thousand eight hundred and fifty-five.
Witness,
S. CARPMAEL.
EDWD E. ALLEN. (L.S.)