IMPROVEMENTS IN THE SLIDE VALVES OF COMPOUND STEAM ENGINES
Year: 1873

page_text: LETTERS PATENT to Charles John Galloway and John Henry Beck-
with, both of Manchester, in the County of Lancaster, for the In.
vention of "IMPROVEMENTS IN THE SLIDE VALVES OF COMPOUND STEAM
ENGINES."
PROVISIONAL SPECIFICATION left by the said Charles John Galloway
and John Henry Beckwith at the Office of the Commissioners of
Patents, with their Petition, on the 5th May 1873.
WC, CHARLES JOHN GALLOWAY and JOHN HENRY BECKWITH, both
of Manchester, in the County of Lancaster, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE SLIDE VALVES OF COM-
POUND STEAM ENGINES," to be as follows:-
•
This Invention relates to a construction and arrangement of the slide
valves of compound steam engines which have their high and low-
pressure cylinders placed side by side, and their pistons reciprocating in
opposite directions, or nearly so, the object of the improved construction
and arrangement being to reduce as much as possible the space of passage
from the one cylinder to the other, and the frictional pressure of the
slides upon the facings of the ports. For this purpose we employ

page_text: separato slides for supply and exhaust, whereby the necessity for an
exhaust cavity in cach slide, as in a D slide, is avoided. The area of the
slide is thus reduced, as it is only that which is necessary to cover the
port and give the lap, and the frictional pressure on the faces is pro-
portionally diminished. Morcover, by the arrangement of such slides
in the manner we will now describe, the passage from the one cylinder
to the other may be reduced to a minimum.
The two cylinders being placed side by side with their axes parallel,
we provide on the outer side of the high-pressure cylinder a jacket with a
port and a slide at each end for admitting the high-pressure steam. On 1
the outside of the low-pressure cylinder we make a similar provision for
the discharge of the exhaust steam after having done its work.
Between the two cylinders we likewise provide a pair of slides, one at
cach end, working in a direct passage from the high-pressure cylinder to
the low-pressure cylinder. These slides, having no exhaust cavity, may
all be flat plates of such size as to cover the ports and give the necessary
lap, made to reciprocate rectilincally; or they may be of cylindrical
form, having reciprocating rotary movement, a steam-way being formed
through them as through the plug of a stop-cock, or they may be of
semi-cylindrical form, offering a steam-way past one side when turned
into one position, and closing it when turned into another position.
These three sets of slides may receive their motion from one eccentric,
but we prefer to move the slides first named, that is to say, those for
admitting steam to the high-pressure cylinder with a variable travel, so
that while their lead remains constant they may be made to cut off the
steam supply, sooner or later, for working the high-pressure steam more
or less expansively.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles John Galloway and John Henry Beck-
with in the Great Seal Patent Office on the 18th September 3
1873
Howay
with in the Great Seal Patent Office on the 18th September 30
1873
TO ALL TO WHOM THESE PRESENTS SHALL COME, wc, CHARLES
JOHN GALLOWAY and JOHN HENRY BECKWITH, both of Manchester, in
the County of Lancaster, send greeting.
TO ALL TO WHOM THESE PRESENTS SHALL COME, wc, CHARLES
JOHN GALLOWAY and JOHN HENRY BECKWITH, both of Manchester, in
the County of Lancaster, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of May, in the year of our
Lord One thousand eight hundred and seventy-three, in the thirty-sixth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto us, the said Charles John Galloway and John Henry Beck-
with, Her special license that we, the said Charles John Galloway and
John Henry Beckwith, our executors, administrators, and assigns, or
such others as we, the said Charles John Galloway and John Henry
Beckwith, our exccutors, 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 THE SLIDE VALVES OF COMPOUND STEAM ENGINES," upon the
condition (amongst others) that we, the said Charles John Galloway
and John Henry Beckwith, our executors or administrators, by an instru-
ment in writing under our or their hands and seals, or under the hand
and scal of one of us or them, should particularly describe and ascertain
the nature of the said Invention and in what manner the same was to
be performed, and cause the samo 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 John Henry Beckwith, on behalf of
myself and the said Charles John Galloway, do hereby declare the
nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, reference being had to the accompanying
Sheet of Drawings, and to the figures and letters marked thereon, that
is to say :-
This Invention relates to a construction and arrangement of the slide
valves of compound steam engines which have their high and low-
pressure cylinders placed side by side, and their pistons reciprocating in
opposite directions, or nearly so, the object of the improved construction
and arrangement being to reduce as much as possible the space of passage
from the one cylinder to the other, and the frictional pressure of the
slides upon the facings of the ports. For this purpose we employ
separate slides for supply and exhaust, whereby the necessity for onc
exhaust cavity in each slide, as in a D slide, is avoided. The area of

page_text: the slide is thus reduced, as it is only that which is necessary to cover
the port and give the lap, and the frictional pressure on the faces is
proportionally diminished. Morcover, by the arrangement of such
slides in the manner we will now describe, the passage from the onc
cylinder to the other may be reduced to a minimum.
The two cylinders being placed side by side, with their axes parallel,
we provide on the outer side of the high-pressure cylinder a jacket with
a port and a slide at each end for admitting the high-pressure steam. On
the outside of the low-pressure cylinder we make a similar provision for
the discharge of the exhaust steam after having done its work.
Between the two cylinders we likewise provide a pair of slides, one at
cach end, working in a direct passage from the high-pressure cylinder to
the low-pressure cylinder. The slides, having no exhaust cavity, may
all be flat plates of such size as to cover the ports and give the necessary
lap, made to reciprocate rectilincally, or they may be of cylindrical form,
having reciprocating rotary movement, a steam-way being form
through them as through the plug of a stop-cock; or they may be of
semi-cylindrical form, offering a steam-way past one side when turned
into one position, and closing it when turned into another position.
These three sets of slides may receive their motion from one eccentric;
but we prefer to move the slides first-named, that is to say, those for
admitting steam to the high-pressure cylinder with a variable travel, so
that while their lead remains constant they may be made to cut off the
steam supply, sooner or later, for working the high-pressure steam more
or less armancival

page_text: at each end alternately by the passages E' and E' fitted with the couplod
slidos e¹ and e² into the external jacket E, whence it is discharged to the
condenser. The slides & and d², as well as the slides e¹ and e³, are
preferably coupled by rods having right and left screws with clamp nuts
at and e³, so that the distance of the one slide from the other can be
accurately adjusted to the position of the ports which they respectively
cover.
The pistons of the two cylinders A and B working always in opposite
directions, or nearly so, all the slides as arranged may be worked simul-
taneously from one eccentric or cam on the engine shaft. We prefer,
however, to work together only the two pairs of slides d³, d³, and
e, e, working the first pair c', c², from a separate cam or eccentric,
so that the cut-off of the high-pressure supply steam may be varied
without interfering with the free discharge of the steam by the ports
D¹, D², and E', E³.
Fig. 3 represents a partial sectional plan, and Fig. 4 a partial longi-
tudinal section of a modified form of the middle slides d¹ and №.
According to this modification the mouths of the ports are somewhat
widened, and the slides are made with cavities in their faces like an
ordinary D slide. It will be seen that when these slides are moved so
as to uncover the ports, as d in Fig. 4, a larger area of opening is
afforded through the port, the steam not only passing the edge of the
slide but also flowing by the D shaped cavity into the port.
Fig. 5 represents a partial sectional plan, and Fig. 6 a partial longi-
tudinal section of the middle valves constructed, as above described, to
act by partial rotation instead of sliding. The slides f" and ƒ are here
each of the form of a segment of a cylinder somewhat larger than half
the cylinder mounted on a shaft F, which is passed through a stuffing
box in the side of the jacket, and has fixed on it a lever arm G. The
arms G being connected by rods to each other, and to the eccentric cam
or other moving part, the two slides are caused simultaneously to make
a partial rotation, so that the one (as g', Fig. 6) closes the port, and the
other (as g, Fig. 6) opens the port, and conversely on their back stroke,
the shaft F where it passes through the body of the slide may be made
rectangular, as shewn in Fig. 6, or polygonal in section, or it may be
round, with a key or feather to ensure the slide turning with it as may
be readily understood.

page_text: Although in Figs. 3, 4, 5, and 6 wo have shewn modified forms of
slides as applied between the two cylinders, similar slides might
obviously be applied also for admission of the high-pressure steam, and
for the final discharge of the steam from the low-pressure cylinder.
Having thus described the nature of our Invention, and in what
manner the same is to be performed, we claim in respect of compound
steam engines which have their low and high-pressure cylinders placed
side by side, and the pistons of those cylinders reciprocating in opposite
directions, or nearly so,-
First. The arrangement of three pairs of flat slides, substantially as
herein described in reference to Figs. 1 and 2.
Second. The use in the arrangement of slides above referred to of one
or more pairs of cylindrical slides, substantially as herein described in
reference to Figs. 5 and 6.
In witness whereof, I, the said John Henry Beckwith, have here-
unto set my hand and seal, this Second day of August, in the
year of our Lord One thousand eight hundred and seventy-three.
JOHN HENRY BECKWITH. (L.S.)