IMPROVEMENTS IN COMPOUND STEAM ENGINES
Year: 1854

page_text: LETTERS PATENT to Joseph Shepherd, of Manchester, in the County of
Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN COMPOUND
STEAM ENGINES."
Sealed the 7th November 1854, and dated the 10th May 1854.
PROVISIONAL SPECIFICATION left by the said Joseph Shepherd at the
Office of the Commissioners of Patents, with his Petition, on the 10th
May 1854.
I, JOSEPH SHEPHERD, of Manchester, in 'the County of Lancaster, Engineer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
COMPOUND STEAM ENGINES" to be as follows:-
My Invention relates to compound engines, or such as are provided with
high pressure and low pressure cylinders, and consists in so arranging the
former of these that one side of the piston or pistons is acted upon by high
pressure steam, while the other is in communication with the condenser;
the steam, having thus operated, passes as usual into the low pressure
cylinder.
An arrangement I adopt for carrying out this principle, and which will
serve to illustrate my Invention, is as follows:-I arrange two cylinders, end to
end, in which there are pistons connected together, by which arrangement
four chambers are formed in a line with each other thus,-

page_text: the last compartment i will be open to the low pressure cylinder: at the end
of a stroke the valves are so shifted as to admit steam to the chamber 1 and
open the chamber 2 to the condenser, at which time a small quantity of steam
is allowed to pass into No. 3, and No. 4 is in communication with the low
pressure cylinder, and so on.
The above description will point out the main features of my Invention but
•
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Joseph Shepherd in the Great Seal Patent Office on the
10th November 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPHI
SHEPHERD, of Manchester, in the County of Lancaster, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Tenth day of May, in the year of our Lord
One thousand eight hundred and fifty-four, in the seventeenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Joseph Shepherd, Her especial licence that I, the said
Joseph Shepherd, my executors, administrators, and assigns, or such others
as I, the said Joseph Shepherd, 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 COMPOUND STEAM ENGINES," upon the condition (amongst
others) that I, the said Joseph Shepherd, by an instrument in writing under
my hand and seal, should particularly 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 Joseph Shepherd, do hereby declare
the nature of my 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 and accompanying Drawings (that is to say):-
My Invention relates to compound engines (or such as are provided with.
high pressure and low pressure cylinders), whereby I am enabled to cause a
piston to be acted upon on one side by high pressure steam whilst the other

page_text: side thereof is in communication with the condenser. This I accomplish by
the employment of two high pressure cylinders working in conjunction with
the low pressure cylinder.
And in order that my Invention may be fully understood; I have appended
to this my Specification a Sheet of illustrative Drawings, which I will now
proceed to describe.
Fig. 1 is à longitudinal sectional view of one arrangement I adopt; and
Fig. 2, a cross section of the same, in which a, a, b, b, are the two high
pressure cylinders connected together by metal c, but furnished with openings
d, d, e, e, at that part, in order to afford access to the stuffing boxes f, g, through
both of which the piston rod h passes. This rod carries two pistons i, j, and
the cylinders, are therefore divided into four compartments 1, 2, 3, 4. The
compartments 1, 4, are capable of being opened to the slide valve box k, by
means of the passages l, m, and also to the low pressure cylinder through the
passages, o, the two latter being connected together by a longitudinal
chamber p. The compartments 2, 3, have passages q, r, which are alternately
opened to a longitudinal chamber s, from whence a pipe proceeds to the con-
denser. The valves for effecting these changes are shewn at t¹, t, t³, t', formed
in one piece, or connected together in their proper relative positions by means
of the rod u, provided with suitable screw nuts. The several parts being in
the positions shewn in the Drawings, the action will be as follows:-Steam
being admitted from the boiler by the pipe v, will flow through the p
passage ว
into the compartment 4, and there exert its expansive force against the
piston i, at which time the compartment 3 is open to the condenser by the
passages r, s, and pipe w; at the same time the steam, which has already
acted against the piston j of the compartment 1, will flow through the
passages m, o, p, and from thence by the pipe a to the low pressure cylinder.
The withdrawal of the piston j from the end of its cylinder would necessarily
cause a vacuum in the compartment 2; in order to avoid which, a small
aperture y, formed through a lap of the valve 3, will arrive opposite to the
opening 9, and allow a slight quantity of steam from the boiler to pass into
the cylinder. A stroke having been performed, the slide valves will be shifted
by an excentric, or by other ordinary means, so as to bring them into the
position shewn by red lines in Fig. 1; at which time steam will be admitted
from the boiler through the opening m into the compartment 1, and that
which was allowed to pass into the cylinder through orifice y will be free
to flow into the condenser through the passages q, s. In the cylinder a,
the compartment 4 will now be open to the low pressure cylinder, and a
small quantity of steam will be admitted into the compartment-3 by means

page_text: of the orifice, and so on, the high pressure steam acting alternately in 4 and
1, at the same time that 3 and 2 are alternately in communication with the
condenser. The low pressure cylinder may be placed by the side of those
shewn at a, b, and connected (together with the rod h) to a shaft in any ordi-
nary manner. Fig. 3 represents in vertical section another method of com
bining the two high pressure cylinders. In this instance the one is placed
above the other; but the two pistons i, j, are, as before, affixed to one piston
rod h, to which a link is jointed, connected at its other end to a beam A, forked
at its outward. end, so as to allow the piston rod to pass. The two cylinders
a, b, are provided with slide valves t', t, t, t, as in Figs. 1, 2, but in this
instance they are supposed to be worked by separate rods; their action, how-
ever, will be precisely the same, and as the same letters of reference as were
previously used are marked upon corresponding parts, no further description
will be necessary. Fig. 4 represents in vertical section a further modification
my Invention. One of the high pressure cylinders a, provided with a piston i,
is connected to a beam A, and the piston of the second is also connected
to the same beam, but at a point nearer to the centre of motion, and the
stroke is therefore proportionately diminished. The valves, as in the last case,
are worked by separate rods, and the operation being the same, will be clearly
understood by reference to letters and numbers marked upon corresponding
parts. Instead of employing the beam A, two cylinders for equal strokes may
be placed side by side, and the piston rods connected to a cross-head; and
other alterations in arrangements, it will be evident, may be made according
to desire.
of
Having thus described and ascertained the nature of my said Invention, and
the manner in which the same is to be performed, I desire it to be understood
that I claim, as secured to me under the above in part recited Letters Patent,
the employment of two high pressure cylinders in combination with a low
pressure cylinder, the former being provided with suitable passages and valves
for opening one side of the pistons during the whole of a stroke alternately to
the condenser.--.
In witness whereof, I, the said Joseph Shepherd, have hereunto set my
hand and scal, this Ninth day of November, in the year of our Lord
One thousand eight hundred and fifty-four.
JOSEPH SHEPHERD.
(L.S.)