CERTAIN IMPROVE- MENTS IN STEAM ENGINES
Year: 1857

page_text: LETTERS PATENT to George Holcroft, of the City of Manchester, Con-
sulting Engineer, and George Denholm, of Wigan, in the County of
Lancaster, Consulting Engineer, for the Invention of "CERTAIN IMPROVE-
MENTS IN STEAM ENGINES."
Sealed the 21st May 1858, and dated the 8th December 1857.
PROVISIONAL SPECIFICATION left by the said George Holcroft and
George Denholm at the Office of the Commissioners of Patents, with
their Petition, on the 8th December 1857.
We, GEORGE HOLCROFT, of the City of Manchester, Consulting Engineer,
and GEORGE DENHOLM, of Wigan, in the County of Lancaster, Consulting
Engineer, do hereby declare the nature of the said Invention for "CERTAIN
IMPROVEMENTS IN STEAM ENGINES," to be as follows:-
The nature of our Invention consists in an improved horizontal double-
acting compound steam engine, the high-pressure and low-pressure cylinders
of which are placed in a line with each other, so that the positions of both
cylinders may be fixed to the same piston rod, and this piston rod is connected
to the crank shaft by a connecting rod of the usual construction. By this
arrangement a pair of horizontal double-acting compound steam engines may
be connected to the same crank shaft, the engines working at right angles.
The steam is admitted to and conveyed from the high-pressure and low-
pressure cylinders by suitable valves and gear.

page_text: Another part of our Invention consists in the pistons of horizontal steam
engines; we make additional packing rings either entire or of about half the
circumference of the piston, to prevent the steam passing between the upper
part of the piston and the cylinder; also in applying a roller or pulley sup-
ported in a weighted lever, or by springs to the piston rods of horizontal
engines to assist in balancing the weight of the piston and rod.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Holcroft and George Denholm in the Great Seal
Patent Office on the 8th June 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, GEORGE
HOLCROFT, of the City of Manchester, Consulting Engineer, and GEORGE
DENHOLM, of Wigan, in the County of Lancaster, Consulting Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighth day of December, in the year of our Lord
One thousand eight hundred and fifty-seven, in the twenty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us,
the said George Holcroft and George Denholm, Her special licence, that
we, the said George Holcroft and George Denholm, our exccutors, adminis-
trators, and assigns, or such others as we, the said George Holcroft and
George Denholm, our executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after 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 "CERTAIN
IMPROVEMENTS, IN STEAM ENGINES," upon the condition (amongst others) that.
we, the said George Holcroft and George Denholm, our executors or adminis-
trators, by an instrument in writing under our, or their, or one of our or their
hands and seals, 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 we, the said George Folcroft and George Denholm,
do hereby declare the nature of our said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement (that is to say): -

page_text: The nature of our Invention consists in an improved horizontal double-
acting compound steam engine, the high-pressure and low-pressure cylinders
of which are placed in a line with each other, so that the pistons of both
cylinders may be fixed to the same piston rod, and this piston rod is connected
to the crank shaft by a connecting rod of the usual construction. By this
arrangement a pair of horizontal double-acting compound steam engines may
be connected to the same crank shaft, the cranks being placed at right angles,.
also in applying rollers or pulleys to support the piston rods of horizontal
engines.
And in order that our Invention may be fully understood and readily,
carried into effect, we will proceed to describe the accompanying Sheet of
Drawings, reference being had to the figures and letters marked thereon.
Fig. 1 is a side elevation, and Fig. 2 a plan, of our improved horizontal
double-acting compound steam engine. a is the high-pressure steam cylinder,
and 6 the low-pressure cylinder; these cylinders are placed in a line with
each other, so that the piston rod c may work in the stuffing boxes of both
the cylinders. The pistons of both the cylinders are fixed to the piston rod c,
the end of which is provided with a cross head c¹, to which the connecting rod
d is coupled; this connecting rod is also coupled to the crank e fixed to the
shaft f. The piston rod c is supported between the two cylinders by the pulley
or roller c, and at the outer end by the pulley or roller c³; the axles of these
pulleys or rollers revolve in adjustable bearings, thereby assisting to support
the weight of the piston rod and pistons. These pulleys or rollers are applicable
to horizontal steam engines of the usual construction. When a pair of engines
are required, the piston rod of the other cylinders may be connected to the
crank e', see Fig. 2. By this arrangement the cranks e and e¹ may be placed
at right angles to each other, as in single-acting horizontal engines of the
usual construction; whereas when the cylinders of compound horizontal
engines are not in the same line this advantage cannot be attained.
The steam is admitted to the high-pressure cylinder a through the pipe g,
the ingress valve in the box h, and side pipes i andj; and it is conveyed back
again from the high to the low-pressure cylinder 6 through the pipes i and j,
and through the egress valves in the box h; the steam passes from the low-
pressure cylinder 6 to the air pump and condensor through the exhaust
valves k, k, and pipes m. The requisite gear for working the air pump and
the steam valves is clearly shewn in the Drawing; but as this gear and the
valves for admitting and shutting off the steam are well understood by person
conversant with compound steam engines, it is, therefore, not necessary to
describe the same in detail.

page_text: We wish also to remark, that we do not limit ourselves to the arrangement
of valves and pipes, for conveying the steam to and from the cylinders, as
these valves and pipes may be arranged in various other ways.
Having thus stated the nature of our Invention, and described the manner
of carrying the same into operation, we declaro that we claim,-
First, the so arranging the cylinders of compound steam engines that the
pistons of the high-pressure and low-pressure cylinders may be fixed to tho
same piston rod.
And, secondly, the application of pulleys or rollers to support the piston
rods of horizontal steam engines.
In witness whereof, I, the said George Holcroft, have hereunto set my
. hand and seal, this Seventh day of June, in the year of our Lord
One thousand eight hundred and fifty-eight.
Witness,
H. B. BARLOW,
Manchester.
GEO. HOLCROFT. (L.S.)