IMPROVEMENTS IN STEAM ENGINES
Year: 1875

page_text: LETTERS PATENT to Henry Hughes, of Leicester, in the County of
Leicester, Mechanical Engineer, for the Invention of "IMPROVEMENTS
IN STEAM ENGINES."
Sealed the 6th December 1875, and dated the 8th June 1875.
PROVISIONAL SPECIFICATION left by the said Henry Hughes at the
Office of the Commissioners of Patents, with his Petition, on the
8th June 1875.
I, HENRY HUGHES, of Leicester, in the County of Leicester,
Mechanical Engineer, do hereby declare the nature of my said Invention
for "IMPROVEMENTS IN STEAM ENGINES," to be as follows:-
My Invention relates more particularly to that description of engine
for which Letters Patent were granted to me, bearing date and numbered
respectively, November 3rd, 1874, No. 3787, November 19th, 1874,
No. 3976, and February 1, 1875, No. 372, and consists of an improved
construction and arrangement of the cylinders and pistons, whereby the
expansive power of the steam is utilized to its maximum extent and

page_text: a more effective guide is obtained for the pistons so as to prevent any
concussion upon the connecting rods.
In carrying out my Invention I form each of the two cylinders
described in my former Specifications double, that is to say, in two
chambers or compartments of different areas, in which work double
pistons so constructed that whilst one portion or the head of the piston
fits the larger chamber of the respective cylinder, the other portion
which forms a tail or projection to the head fits the smaller chamber of
such cylinder. The steam is introduced into the small chambers of the
two cylinders alternately behind the tail of the piston, and after per-
forming its duty therein is exhausted into the larger chamber of the
opposite cylinder behind the head of its piston, and thence into the
atmosphere or elsewhere as required. The pistons are thus supported
by the back pressure in the small chamber, and increased steadiness in
their motion is ensured.
The two large chambers form with the intervening chamber described
in my said former Specifications, one cylinder which may be either cast
in one piece, or in two or more pieces bolted together as desired. The
elongated pistons may be cast hollow in one piece, or the head and tail
(that is to say, the large piston and the small piston) may be constructed
separately and connected together by a rod. Longitudinal passages are
provided in the side of the casing for establishing a communication
between the valve box of each cylinder with the large chamber of the
opposite cylinder and the whole of the ports (viz. the steam ports, the
intermediate ports communicating between the two cylinders, and the
final exhaust ports) may be opened and closed by a single slide valve
for each cylinder, the two valves being operated by a single eccentric
working against adjustable rings fitted on the valve rods or against
straps and rods in the usual manner.
:
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Hughes in the Great Seal Patent Office
on the 8th December 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
HUGHES, of Leicester, in the County of Leicester, Mechanical Engineer,
send greeting.
3

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of June, in the year of
our Lord One thousand eight hundred and seventy-five, in the 38th
year of Her reign, did, for Herself, Her heirs and successors, give and
3 grant unto me, the said Henry Hughes, Her special license that I, the
said Henry Hughes, my executors, administrators, and assigns, or such
others as I, the said Henry Hughes, my executors, administrators, or
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 Henry Hughes, my
executors or administrators, 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 Henry Hughes, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the accompanying Drawings
and to the letters and figures marked thereon, that is to say :-
My said Invention relates to that description of engine in respect of
which Letters Patent were granted to me, bearing date and numbered,
respectively, November Third, One thousand eight hundred and seventy-.
four, No. 3787 ;. November Nineteenth, One thousand eight hundred
and seventy-four, No. 3976; and February First, One thousand eight-
hundred and seventy-five, No. 372, and consists of an improved
construction and arrangement of the cylinders and pistons, whereby the.
expansive power of the steam is utilized to its maximum extent, and a
more effective guide is obtained for the pistons so as to prevent any
concussion upon the connecting rods.
In carrying out my Invention I form each of the two cylinders,
described in my former Specifications double, that is to say,
in two
chambers or compartments of different areas, in which work double

page_text: pistons so constructed that whilst one portion or the head of the piston
fits the larger chamber of the respective cylinder, the other portion
which forms a tail extending from the head fits the smaller chamber of
such cylinder.
The steam is introduced into the small chambers of the
"two cylinders alternately behind the tail of the piston, and after
performing its duty therein is exhausted into the larger chamber of the
opposite cylinder behind the head of its piston, and thence into the
atmosphere or elsewhere as required. The pistons are thus supported
by the back pressure in the small chamber and increased steadiness in
their motion is ensured.
•
And in order that my said Invention may be fully understood, I shall
now proceed more particularly to describe the same, and for that purpose
shall refer to the several Figures on the annexed Sheet of Drawings,
the same letters of reference indicating corresponding parts in all the
Figures.
Figure 1 of the accompanying Drawings represents a horizontal section
of an engine constructed according to my Invention; Figure 2 is a side
elevation and partial section of the same; and Figures 3 and 4 are
transverse sections taken respectively along the lines 1, 2, 3, 4, Figure 1.
A, B, are the cylinders, cach forming two chambers or compartments
a, a¹, and b, b¹, respectively of different arcas, in which work double
pistons consisting of heads C, D, which fit the larger chambers a, b, of
the cylinders A, B, and tails C¹, D¹, fitting the smaller chambers a¹, b¹,
respectively of such cylinders.
The two large chambers a, b, form with the intervening chamber E
one cylinder, which may be either constructed in two or more pieces
bolted together as shewn, or cast in one piece if desired. The double
pistons may each be either cast in one piece as shewn in the Drawing,
or the large piston and the small piston of each double piston may be
constructed separately and connected together by a rod. The pistons
are connected to the crank pin F of the crank shaft G by means of
connecting rods H, I, formed with recessed heads K, L, which fit around
the crank pin F, as described in my said former Specification No. 3787".
In the side of the casing there are formed longitudinal passages c, d,
the former of which (c) establishes a communication between the port e
of the cylinder B and the chamber a of the cylinder A, whilst the
latter (d) forms a similar communication between the port f of the
.

page_text: cylinder A and the chamber 6 of the cylinder B. The port f and the
steam inlet port 9 and the exhaust port h of the cylinder A are all
opened and closed by a single slide valve i, enclosed in a valve box k
and the port e, and the steam inlet port and the exhaust port m of the
opposite cylinder B are all opened and closed by a similar valve n
enclosed in a valve box o. The valves i, n, are both operated by a single
eccentric p, mounted upon the crank shaft G, and working by preference
against adjustable rings q, r, fitted upon the valve rods s, t, as shewn,
or the eccentric may be provided with a strap in the usual manner.
A suitable fly wheel M is mounted upon the crank shaft G.
The engine operates in the following manner :-Assuming the valves.
to be in the position shewn in the Drawing the steam is entering
through the port into the chamber 6' at the back of the piston D', and
forcing that piston together with the piston D forward towards the
centre, and thus carrying the crank pin F round one half of its revolution,
and the pistons C and C¹ of the opposite cylinder A by reason of their
connection with the crank pin F are simultaneously forced back in the
direction of the arrow to the end of their respective chambers a, a¹. The
steam which had previously filled the chamber a¹ is at the same time
exhausting through the ports g and f and the passage d into the
chamber of the opposite cylinder B, and there acting at the back of
the piston D, and thus forming an auxiliary to the steam which is acting
at the rear of the piston D¹, in effecting the stroke of the double
piston D, D'. The exhaust steam which was previously contained in
the chamber a of the cylinder A is at the same time exhausted through
the passage c and the ports e, m, into the atmosphere or elsewhere as
required. When the pistons D, D¹, with the pistons C, C¹, have arrived
at the end of their stroke made in the direction of the arrows the steam.
is cut off from the chamber 6' of the cylinder B, and steam is introduced
into the chamber a¹ of the cylinder A. The steam which had previously
filled the chamber 6' of the cylinder B is then exhausted through the
ports and e, and the passage c into the chamber a of the cylinder A,
and acts at the rear of the piston C during the motion of the pistons
in the reversed direction, the waste steam previously contained in the
chamber 6 of the cylinder B being simultaneously exhausted through
the passage d and ports f and h into the atmosphere or elsewhere as
before explained. On the completion of the stroke the steam is again cut
off from the chamber a¹ of the cylinder A, and admitted into the

page_text: chamber 6¹ of the cylinder B, and the operations herein-before described
are repeated, and so on in succession. The expansive power of the steam
is thus utilized to its maximum extent, the pistons are constantly
supported by the back pressure of the steam exhausting from the
smaller chamber of the one or the other of the cylinders A, B, and a
uniform and steady motion is thereby obtained.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is, constructing
the cylinders of engines of the description herein mentioned double or
with two chambers of different areas for the reception of double pistons
to be operated by steam admitted to the smaller chambers of the two
cylinders alternately, and exhausting into the larger chamber of the
opposite cylinder, substantially as and for the purposes herein-before
described and as illustrated by my Drawings.
In witness whereof, I, the said Henry Hughes, have to this my
Specification set my hand and seal, this Fourth day of December,
One thousand eight hundred and seventy-five.