CERTAIN IMPROVEMENTS IN STEAM ENGINES
Year: 1857

page_text: LETTERS PATENT to William Hopkinson, of Huddersfield, in the County
of York, Engineer, for the Invention of "CERTAIN IMPROVEMENTS IN
STEAM ENGINES."
Sealed the 29th January 1858, and dated the 1st August 1857.
PROVISIONAL SPECIFICATION left by the said William Hopkinson, at
the Office of the Commissioners of Patents, with his Petition, on the
1st August 1857.
I, WILLIAM HOPKINSON, of Huddersfield, in the County of York, Engineer,
do hereby declare the nature of the said Invention of "CERTAIN IMPROVE.
MENTS IN STEAM ENGINES," to be as follows:-
My said Invention has reference to the working of slide valves in steam-
engines, and to the valve gear thereof, and also to a new arrangement of
the parts of compound engines. It consists,-
Firstly, in modifying the motion of the slide, by working the same from a
pin in the conjugate diameter of one of a pair of elliptic wheels, the resulting
motion being thereby rendered relatively slower in the middle, and quicker
near the ends of the traverse of the slide.
Secondly, in an arrangement of valve gear, which makes the arc of vibra-
tion of the valve lever variable at discretion, while the engine is in motion;
for the purpose of altering the length of the traverse of the slide, the eccentric
rod acts upon the valve lever, through the intervention of a slotted lever, into

page_text: the slot or opening of which the stud pin of the valve lever enters, and the
fulcrum of which is moveable by a screw and nutt, or equivalent means; by
moving the fulcrum of the slotted lever, so as to vary the distance thereof,
from the stud pin, the lengths of the vibration of the valve lever, and of the
traverse of the slide are varied accordingly.
Thirdly, in an arrangement of valve gear, by which the relative velocities of
the slide at different parts of its traverse are made susceptible of variation,
while the engine is in motion. The stud pin of the valve lever, enters a slot
or longitudinal opening in a link, which forms part of a jointed lever, the
fulcrum of which is moveable by a screw and nutt or equivalent means, so
that the stud pin can be adjusted to any part of the slot; each end of the
slotted link receives a reciprocating motion from the fly wheel shaft, through
the medium of a distinct pair of elliptic wheels, which latter are arranged
and geared in such manner that they cause the ends of the slotted link to
vibrate or traverse through equal spaces, and in equal times, but with differently
varying velocities, one end of the slotted link receiving a motion which is
relatively quick in the middle, and slow near the ends of its traverse, and the
other end a motion which is the converse of this, or relatively slow in the
middle, and quick near the ends of the traverse. The movement of the valve
lever, and the traverse of the slide correspond with either of these extremes
or with any mean between them, according to the part of the slot in the before-
mentioned link, which the valve lever pin is made to occupy.
Fourthly, in a new arrangement of the parts of compound engines, or
engines having two cylinders, the principal features of which are, firstly, the
juxtaposition of an horizontal with a vertical cylinder, so that the steam pas-
sages between the two cylinders, or between both cylinders and a common
condenser, may be short; and, secondly, the position of the horizontal cylinder
on that side of the vertical cylinder which is the opposite or contrary of that
on which the fly wheel and first motion wheels are situate, so that the pistons
of both cylinders can be connected together by a short supplementary shaft,
without intermediate wheels or gearing.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Hopkinson in the Great Seal Patent Office on
the 1st February 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM 3
HOPKINSON, of Huddersfield, in the County of York, Engineer, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of August, 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 me, the said William Hopkinson,
Her special licence that I, the said William Hopkinson, my executors,
administrators, and assigns, or such others as I, the said William Hopkin-
son, 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 of years therein mentioned, 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 of "CERTAIN
IMPROVEMENTS IN STEAM ENGINES," upon the condition (amongst others) that
I, the said William Hopkinson, 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 William Hopkinson, do hereby
declare that the nature of my said Invention, and the manner in which the same
is to be performed, are particularly described and ascertained, with the aid
of the annexed Drawings, by the following statement (that is to say) :-
:-
My said Invention has reference partly to the working of the slide valves of
steam engines, and partly to the arrangement of the parts of engines having-
two steam cylinders, and consists in the several improvements herein-after
described.
My first improvement which relates to the working of slide valves is an
arrangement of valve gear, whereby the motion of the slide is so. modified as
to be relatively slower in the middle and more rapid near the extremes of the
traverse, as compared with the like motion derived from the common eccentric.
This result is attained by transmitting the motion for working the slide
through a pair of equal and similar oval or elliptic toothed wheels, the first of
which is fixed on the fly wheel shaft, the second on a counter shaft or separate
stud, the connecting rod being attached to the second wheel by a pin or stud
inserted in such a position that it shall always be at one of the dead points
in its orbit at the same time that the transverse axis or diameter of the
first wheel is in a line with the conjugate axis or diameter of the second
wheel;
the effect of this arrangement is, that the steam ways are opened. and
closed quickly by the rapid movement of the slide when near the limits of its
traverse; while; in consequence of its retardation in the middle of its course,

page_text: the lap is caused to dwell longer over the ports, a mode of working which
operates beneficially, by cutting off the steam early and allowing it to act by
expansion during the remaining part of the stroke.
In the most ordinary
and familiar position of a pair of wheels such as those described, namely, that
in which a line joining their centres of motion will lie in the same direction
with the connecting rod, the pin or stud, whereby the latter is attached, will
be in the conjugate diameter of the second wheel. The arrangement in this
case is shewn in Figure 1 of the Drawings, in which a' is the first wheel, or
that on the fly wheel shaft; a³, the second wheel, or that on the counter shaft ;
b is the connecting rod; a, the pin by which it is attached to the wheel a²; c
is the valve lever. If, however, the line joining the centres of motion of the
two wheels, is at right angles to the direction of the connecting rod, the pin or
stud by which the latter is attached must be in the transverse diameter of the
second wheel as the pin n² is represented on the wheel n in Figure 3. If the
line joining the centres of motion of the two wheels forms an oblique angle
with the direction of the connecting rod, the angular distance of the pin or
stud from the conjugate diameter of the second wheel must be equal to that
angle.
The second of my improvements in the working of slide valves is an arrange-
ment of valve gear, whereby the length of the arc, through which the valve
lever vibrates, is made subject to variation while the engine is in motion. For
the purpose of altering from time to time the length of the traverse of the
slide, the eccentric rod acts upon the valve, through the intervention of a
slotted link into the slot or opening of which a stud or pin projects from the
valve lever; the slotted link vibrates upon a moveable fulcrum, which can be
made to approach to or recede from the stud of the valve lever, and by altering
the distance between these parts, the spaces through which the valve lever
vibrates, and through which the slide moves, can be increased or diminished;
the beneficial effect is, that the slide can thus be made to open the steam
ports to a greater or less extent at discretion, so that by throttling or wire-
drawing the steam more or less in its passage through the ports, the pressure
in the cylinder can be modified, so as to adapt it to any variation in the load
of the engine. This arrangement is explained by Figure 2 of the Drawings,
in which d is the slotted link, whose fulcrum is a joint pin d¹ free to move
vertically, but. restrained from moving horizontally by a rod d² connecting it
to any convenient fixed point; d³ is a bell crank lever carried by a fixed stud
or pivot, upon which it can be moved radially, either by manual force, or by
any suitable connection with the governor of the engine, so as to raise or lower
the slotted link d suspended from it by the rod d' and joint pin d³. Upon one

page_text: of the arms of the valve lever e³ is a stud e projecting through a block which
slides in the slot of the link d; the valve lever e¹ is pivoted on a stud e³, and
conveys motion to the slide through its other arm and the valve rod f; g is
the eccentric, the rod of which is attached to the free end of the link d, by a
joint pin g¹. The motion of the eccentric causes the link d to vibrate on the
moveable stud d', carrying with it the stud e, and thus causing the arm of the
valve lever also to vibrate in an arc which will be longer or shorter according
as the link d is lowered or raised.
It
The third of my improvements in working slide valves is an arrange-
ment by which the velocity with which the slide moves through different parts of
its traverse is made capable of being varied while the engine is in motion, in a
manner which I shall describe by the aid of Figure 3 of the Drawings. A
stud or pin h upon the valve lever h' projects through a block k which slides
in the slot or longitudinal opening of the link k'; the link last mentioned
forms part of a flexible or jointed lever, the other part of which is the rod k²,
jointed to k¹ at ; the fulcrum of this lever is a stud or pin 1, carried by the
horizontal arm of the bell-crank lever , the motion of which, upon the
appliance of manual or other force, raises or lowers the link k³, so as to cause
the stud or pin h to occupy any required position in the slot; m is an oval or
elliptic toothed wheel on the fly wheel shaft m'; n and o are two similar
wheels, each gearing with the wheel m, and carried by studs or counter shafts
n and o¹, the whole having the relative positions shewn in the Drawing.
may bere be observed that the three wheels so arranged are equivalent to
two distinct pairs of wheels arranged in diametrically opposite positions.
n2, o are studs or pins upon their respective wheels, to which the opposite
ends of the link k¹ are connected by the rods n³, o³, and joint pins n*, o*; the
wheels n, o, are so disposed, that when the pins n², o², are at the dead points
of their respective orbits, the relative positions of the wheels will be that re-
presented in the Drawing. Bearing in mind the effect of elliptic wheels
in varying or modifying the rotatory velocities of each other, it will be seen,
that as the driving wheel m revolves, the motion of the pin n², as compared
with that of an ordinary crank, will be accelerated at its dead. points, and
ratarded in the middle of its throw, the lap of the valve being thereby made
to dwell longer over the steam ports; while, in the case of the wheel o, the
motion of the pin o² will have, as compared with that of a common crank
pin, a slower velocity at its dead points, and a more rapid one in the middle
of its throw, the lap of the valve being, in consequence, made to dwell less
over the steam ports. Now, the reciprocating motions communicated to the
corresponding ends of the link k', will necessarily have the differently varying

page_text: velocities of the respective pins so that while the ends of the link k movė
through equal spaces, and in equal aggregate times, the end n¹ will have a
motion which is relatively quick near the ends, and slow in the middle of its
traverse, while the motion of the end o will be the converse of this, or
relatively slow near the ends and quick in the middle of its traverse; and it
is evident that the movement of the valve lever and the traverse of the
slide, will correspond with either of these extremes or with any mean
between them, according as the slotted link is raised or lowered, and the
pin h thereby made to approach the one or the other extremity thereof.
I shall now describe that part of my Invention which relates to the arrange-
ment of the parts of engines referring to Figures 4 and 5, the former an
elevation, the latter a ground plan. p is the cylinder, p¹ the beam, p² the
connecting rod, the crank, q' the crank pin, r the fly wheel, and the
fly wheel shaft of a beam engine of ordinary construction; to this engine I
add a second or auxiliary horizontal cylinders, placing the same in the closest
practicable juxtaposition with the original cylinder p, and on that side of the
latter which is furthest from the fly wheel; the connecting rod t conveys
motion to the fly wheel shaft through a short intermediate shaft t', upon
which the connecting rod acts through the crank t; the further end of the
shaft t is furnished with a crank t³, keyed on in a position not diametrically
opposite to that of the crank to, but a little in advance thereof; the pin of the
crank is connected to the crank pin q¹ of the beam engine by a trail link v;
by this means the pistons of both cylinders are made to transmit their impulses
to the fly wheel shaft 7¹. I desire that it may be understood, with reference
to this arrangement, that the novelty thereof does not consist in the use and
application generally of an additional horizontal cylinder with a beam engine,
but only and specially in such use and application under the conditions, and
with the limitations mentioned; namely, that the said cylinder be applied on
the contrary side of the original cylinder from the fly wheel, and that the
piston be connected with the fly wheel shaft without intermediate wheels
or gearing, in the manner described. The advantages of this arrangement
are, firstly, that both eylinders can be made to communicate with a common
condenser, or with each other by short steam passages with little waste of
steam; secondly, that the steam in each cylinder can be made to work
against a vacuum, so that less pressure in the boiler is required to obtain
the same power than in the common compound engines; and thirdly,
that the extra or additional power is transmitted to the fly wheel shaft
without adding to the strain upon the beam.
Having now described the nature of my Invention, and the manner of

page_text: carrying the same into effect, I conclude by declaring that I claim, as of my
Invention, the several arrangements and combinations of parts comprehended
in the mechanism for working slide valves herein-before described, and all
modifications thereof in which the essential characteristics are retained;
and also the arrangement of the parts of a steam engine with two cylinders
herein-before described, so far as the same consists in placing the auxiliary
cylinder as close as possible to the original cylinder, on the side of the latter
most remote from the fly wheel, and in the connection of the piston of the
auxiliary cylinder with the fly wheel shaft, through an intermediate shaft in the
manner pointed out, but not further nor otherwise; and that I do not claim
any of the parts of the valve gear herein-before described or delineated, taken
separately, nor any combinations of such parts, or of any of them, other than
the specific arrangements herein-before particularly described and claimed,
nor any of the parts of the steam engine herein-before mentioned and
described, taken separately, nor any part or parts of the arrangement of such
engine, save and except that which consists in the particular position of the
auxiliary cylinder, and the mode of connecting the piston thereof with the
fly wheel shaft as before described and specifically claimed.
In witness whereof, I, the said William Hopkinson, have hereunto
set my hand and seal, this Thirtieth day of January, in the year
of our Lord One thousand eight hundred and fifty-eight.
WILLIAM HOPKINSON. (L.S.)
Signed and scaled by the said Willliam
Hopkinson, in the presence of,
JN TAYLER, Patent Agent,
Manchester.