CERTAIN IMPROVEMENTS IN ENGINES WORKED BY STEAM AND OTHER ELASTIC FLUIDS, AND IN VALVES
Year: 1870

page_text: LETTERS PATENT to George Holcroft and William Nathan Dack, both
of Manchester, in the County of Lancaster, Engineers, for the
Invention of "CERTAIN IMPROVEMENTS IN ENGINES WORKED BY STEAM AND
OTHER ELASTIC FLUIDS, AND IN VALVES."
Sealed the 19th May 1871, and dated the 3rd December 1870.
PROVISIONAL SPECIFICATION left by the said George Holcroft and
William Nathan Dack at the Office of the Commissioners of
Patents, with their Petition, on the 3rd December 1870.
We, GEORGE HOLOROFT and WILLIAM NATHAN DACK, both of Man-
chester, in the County of Lancaster, Engineers, do hereby declare the
nature of the said Invention for "CERTAIN IMPROVEMENTS IN ENGINES
WORKED BY STEAM AND OTHER ELASTIC FLUIDS, AND IN VALVES," to be as
follows:-
Our Invention consists in connecting the condenser of engines in
which the vacuum is formed by an ejector condenser to an air pump,

page_text: by which combination the air pump carries off the air and gases from
the condenser, also in the application of two or more ejector condensers
to one engine or one condenser.
Our Invention consists in casting one of the cylinders of a compound
engine to the connecting stays described in the Patent granted to us on
the 1st day of April 1869, No. 985.
Our Invention relates also to the valve motion of steam engines, and
it is applicable to the gearing for working the admission valves when
such valves are arranged to close by the action of weights or springs,
or other equivalents.
In performing our Invention we make use of the torsion of a metal
bar or plate, or a twisted or plaited rope for closing and opening the
valve, in lieu of the springs or weights heretofore used for that purpose.
To prevent noise one end of a chain or double link is connected to the
valve rod or lever and the other end to a fixed centre.
Another part of our Invention consists in the apparatus for working
the valves above referred to. A rod, link, or lever is attached to the
lever, which is fast on the valve spindle or weigh shaft, the other end
of this rod, link, or lever is connected to the eccentric rod or rod con
nected to the wrist plate; the rod, link, or lever suspended to the valve
lever has on it a catch which engages in a corresponding recess in the
lever fast to the valve spindle or weigh shaft, or the catch may be
jointed to the rod connected to the wrist plate, or the catch may be on
the lever fixed to the spindle or weigh shaft.
Another arrangement for working the valves consists in connecting
the end of the rod, link, or lever to a catch block fitting in a slot in
the lever fixed on the valve spindle or weigh shaft. A prolongation
of the catch block is connected to an eccentric or lever, the working
centre of which does not coincide with the centre of the lever attached
to the valve spindle or weigh shaft. The eccentric or lever is acted
upon to disengage the catch block by a cam or other equivalent
connected to the governor.
Double slide valves fixed on separate spindles and balanced as
described in the Patent granted to us on the 11th Dec. 1867,
No. 3512, are actuated by a double lever connected to the governor,
so that the variations in the speed of the engine produce a greater
effect on the cut off than heretofore.

page_text: .
Also in an improved circular valve consisting of two ports not
diametrically opposite each other; and two segmental valve facings for
opening and closing the same; the valve is nearly in equilibrium, and
is kept steam-tight by the slightly greater pressure on one side than on
the other; there are passages through the valve for the steam to pass
from one side to the other.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said George Holcroft and William Nathan Dack in
the Great Seal Patent Office on the 2nd June 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, GEORGE
HOLOROFT and WILLIAM NATHAN DACK, both of Manchester, in the
County of Lancaster, Engineers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Third day of December, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said George Holcroft and William Nathan
Dack, Her special licence that we, the said George Holcroft and
William Nathan Dack, our executors, administrators, and assigns, or
such others as we, the said George Holcroft and William Nathan Dack,
our 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
"CERTAIN IMPROVEMENTS IN ENGINES WORKED BY STEAM AND OTHER ELASTIC
FLUIDS, AND IN VALVES," upon the condition (amongst others) that we,
the said George Holcroft and William Nathan Dack, our executors or
administrators, 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.
'

page_text: NOW KNOW YE, that we, the said George Holcroft and William
Nathan Dack, 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 Specification, reference
being had to the two accompanying Sheets of Drawings forming part of
the said Specification:-
Our Invention consists, first, in connecting the condenser of steam
or other engines in which the vacuum is formed by an ejector condenser
to an air pump, by which combination the air pump carries off the air
and gases from the condenser; also in the application of two or more
ejector condensers to one engine or one condensing chamber. This
part of our Invention will be clearly understood without Drawings.
The second part of our Invention is illustrated by Figs. 1 and 2 of
Sheet 1, and it consists in casting or connecting one of the cylinders
of a compound steam engine to the stays described in the Patent granted
to us on the First day of April One thousand eight hundred and sixty-
nine, Number 985.
Fig. 1 represents an elevation partly in section of part of a compound
engine, and Fig. 2 is a transverse section of the same.
a, a, are the
stays to which the high-pressure cylinder 6 is cast, and c is the low-
pressure cylinder, the lid of which fits in an annular recess in the end
of the stays. By this improved construction the ends of the stays
being bored out and faced, the labour is diminished and the centres of
the cylinders are kept in line with each other. This improved con-
struction may be modified by connecting the cylinder 6 and the stays a
by bolts to the main framing, as shewn by dotted lines.
The third part of our Invention, which relates to the valve motion,
is illustrated in Fig. 3 of Sheet 1; it is applicable to the gearing for
working the admission valves when such valves are arranged to close
by the action of weights or springs or other equivalents.
In performing our Invention we make use of the torsion of a metal
bar or plate, or a twisted or plaited rope for closing and opening the
valves in lieu of the springs or weights heretofore used for that purpose.
To prevent noise one end of a chain or double link is connected to the
valve rod or lever and the other end to a fixed centre.
In Fig. 3 d is the ordinary wrist plate, to which the rods e and ƒ are

page_text: jointed for connecting the admission and exhaust valves as usual. When
the valve is closed by the torsion-of a twisted rope, which has been
found in practice to give good results, the rope fits in recesses in the
boss of the lever g, which is connected by the rod / to the lever or
disc i for working the valve. When the valve has been opened to
admit steam it gives increased torsion to the rope, and as soon as the
valve is released the torsion of the rope instantly closes it. We wish
to remark that metal bars or plates may be used instead of the rope
described. To prevent the noise which would be caused by the sudden
action of the lever g, we connect one end of the toggle joint or chain
links to the upper end of the lever g, and the other end to the fixed
centre k.
The fourth part of our Invention is also illustrated in reference to
Fig. 3, and it consists in an arrangement of machinery for working the
valves above referred to. The rod, link, or lever is connected to or
forms part of the catch block ¹ fitting in a slot in the lever or disc i
fixed on the valve spindle n or weigh shaft. The rod, link, or lever
is connected to a link or lever o, the working centre of which does not
coincide with the centre of the lever i, attached to the valve spindle n
or weigh shaft. The link or lever o is acted upon to disengage the
catch block by the cam p or other equivalent connected by the
rod q to the governor.
Our improved apparatus for working the valves above referred to
may be modified in the following manner:-The rod, link, or lever
may be attached to the disc or lever i, which is fast on the valve
spindle n or weigh shaft; the other end of this rod, link, or lever is
connected to the eccentric rod e or rod connected to the wrist plate d.
The rod, link, or lever 7 is suspended to the valve lever i, and a catch
engages in a corresponding recess in the said lever, or the catch may be
jointed to the rod connected to the wrist plate, or the catch may be on
the lever fixed to the spindle or weigh shaft.
The fifth part of our Invention is illustrated in Fig. 4, and it consists
in an improved mode of working the balanced slide valves described in
the Patent granted to us on the Eleventh day of December One thousand
eight hundred and sixty-seyen, Number 3512, or any other slide valve.
r, r, are the spindles of the expansion valves, which are connected by
the links 8, 8, to the double levert hinged on a stud fixed to the

page_text: movable slide u, which is worked by an eccentric or other equivalent.
This double lever is connected by the rod t¹ to the governor, so that
the variations in the speed of the engine produce a great effect on the
expansion or cut-off valves.
On Sheet 2 Fig. 5 is a plan partly in section of the cylinder of a
steam engine to which our improved valve motion is applied; Fig. 6 is
an elevation of the same; Fig. 7 is a section through the line A, B, on
Fig. 5; and Fig. 8 is a transverse section of our improved circular valve.
In Figs. 5 and 6 6 is part of the steam cylinder; w, the slide valve; and
v, v, the cut-off valves. The slide valve w is worked by an eccentric or
its equivalent, as usual, and the cut-off valves v, v, the spindles of which
are connected to the levers 9, 9, jointed to and travelling with the
slide u, traverse to and fro with the eccentric or other equivalent.
When the governor acts on the spindle with the spiral groove x,
which is similar to that described in the Specification of Letters Patent
granted to us on the First day of April One thousand eight hundred
and sixty-nine, Number 985, it liberates the catches ¹ connected to the
levers g, g, from the steel plate u¹ fixed to the slide u, the torsion of
the ropes or other equivalent then acting on the said levers cuts off the
steam. The governor is connected to the spindle x by the rod q¹ and
lever q³, as shewn in Fig. 6.
Our improved circular valve shewn in Fig. 8, consists of two ports,
y.y, not diametrically opposite each other, and two segmental valve
facings, for opening and closing the same, the valve is nearly in
equilibrium, and is kept steam-tight by the slightly greater pressure on
one side than on the other. There are passages ¹ through the valve for
the steam to pass from one side to the other.
Having thus stated the nature of our Invention, and described the
manner of performing the same, we declare that we claim,-
First. Connecting the condenser of steam or other engines in which
the vacuum is formed by an ejector to an air pump, as described.
Secondly. The application of two or more ejector condensers to one
engine or one condensing chamber.
Thirdly. In casting or connecting one of the cylinders of a compound
steam engine to the stays, as shewn and described.

page_text: Fourthly. The application of the torsion of a metal bar or plate, or a
twisted or plaited rope, for closing and opening the valves of steam or
other engines, as shewn and described.
Fifthly. The application of a toggle joint or chain links to prevent
noise in opening and closing the valves of steam and other engines, as
shewn and described.
Sixthly. The improved combinations of machinery, consisting of the
parts marked i, l, l', o, and p, for working the valves of steam and other
engines, as shewn and described in reference to Fig. 3.
Seventhly. The combination of a variable expansion or cut-off gear,
with a movable slide or oscillating lever, as shewn and described in
reference to Figs. 4, 5, 6, and 7, or the combination of any other
expansion or cut-off gear connected to and travelling with a movable
slide or oscillating lever.
And, eighthly. The improved circular valve, shewn and described in
reference to Fig. 8.
-
In witness whereof, we, the said George Holcroft and William
Nathan Dack, have hereto set our hands and seals, this Thirtieth
day of May One thousand eight hundred and seventy-one.
ATO HOLOPOLT
Gol