IMPROVEMENTS IN AND APPLICABLE TO STEAM ENGINES.
Year: 1869

page_text: LETTERS PATENT to George Holcroft and William Nathan Dack,
both of the City of Manchester, Engineers, for the Invention of
"IMPROVEMENTS IN AND APPLICABLE TO STEAM ENGINES.
Sealed the 25th September 1869, and dated the 1st April 1869.
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 1st April 1869.
We, GEORGE HOLCROFT and WILLIAM NATHAN DACK, both of the
City of Manchester, Engineers, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN AND APPLICABLE
as follows:-
STEAM ENGINES," to be
The first part of our Invention is applicable to beam or other vertical
engines, and it consists in an improved mode of trussing or staying the
entablature. A strutt is placed from one wall to the other of the
engine house, and diagonal stay bars are taken from the strutt to a plate
over the entablature. By this means the weight of the walls is brought
on to the columns supporting the entablature.

page_text: Another part of our Invention is applicable to steam engines in which
two steam cylinders are used in line with each other, and it consists in
uniting the cylinders by four or other convenient number of stay bolts,
thereby avoiding the necessity of prolonging the foundation and the
engine bed.
Our Invention relates also to an improved mode of working the valves
of steam engines, described in the Specification of Letters Patent granted
to us on the Eleventh day of December 1867, No. 3512. In the said
Patent we described our improved cut-off or expansion gear, consisting
of a variable stop (acted on and made variable by the action of the
governor) coming in contact with a fixed stop on the valve spindle.
Now according to our present improvements we connect the said differ-
ential stop to an eccentric rod or its equivalent, thereby making it slide
backwards and forwards with it instead of being fixed as described in
the former Patent. This eccentric or its equivalent may be set opposite
to the crank (or otherwise), and by placing a plate or having a facing with
ports between the slide valve and the expansion valves the steam may
be cut off at any part of the stroke of the piston.. The motion of the
valve in this case will be positive and not depending on the friction of
one valve on the other as in the Patent above referred to. This cut-off
gear may also be applied to engines which are reversed by a link or
other reversing motion.
Another part of our Invention consists in varying the point of cut-off
by means of a lever, one end being attached to or in connection with
the spindle of the cut-off valve or to the valve, and the other end fixed.
This lever passes between jaws on a sliding block, and alternately comes
in contact with it. The position of this sliding block is varied by the
action of the governor, and the amount of steam admitted to the cylin-
der is thereby varied according to the load. This arrangement may be
again worked by an eccentric as described above, or the expansion valve
may be carried on the back of the other as in our former Patent. When
worked by an eccentric it would give motion to a second lever by means
of the sliding block coming alternately in contact with it. The sliding
block or differential stop will have a certain amount of play between it
and the lever, so that when it is near the fixed end it will allow it to
traverse further than when near to the end attached to the valve rod,
thereby varying the amount of expansion.
Another part of our Invention consists in the application of a balance

page_text: valve with back plate placed on a plate or facing behind the ordinary
slide valve.
Another part of our Invention relates to the governor rod, which is
made in two parts, each with a head acted upon by springs contained in
a box. When the variable stop of expansion gears is in contact with the
stops connected to the valve spindle or eccentric rod the governor will
be at liberty to act against one of the springs, and when the stop is
released the compressed spring will act on the variable stop of the cut-off
gear to increase or reduce the speed of the engine or amount of steam
admitted into the cylinder.
Another part of our Invention consists in working the valves of steam
engines by applying a catch to the slide worked to and fro by the
eccentric. This catch acts on a sliding block actuated by the governor
or otherwise. When the sliding block is released the valve is instantly
closed by the action of a weight fixed to the centre link of a toggle
joint. This catch may be connected to an eccentric working on a spiral
or screwed shaft, which in moving endwise varies the position of the
eccentric. The spiral or screwed shaft may be used for closing the
admission valve when the governer balls fall below the usual standing
level.
Another part of our Invention consists in applying cylindrical admis-
sion and exhaust valves having a branched connecting passage to steam
engines worked by four valves, the same arrangement being applicable
to engines worked by slide valves.
Another part of our Invention is applicable to the governor, and it
consists in shutting the throttle or admission valve when the governor
balls owing to an accident suddenly collapse. This is effected by causing
the sliding bush of the governor to act on the screwed, eccentric, or
other agent by which the throttle or admission valve is worked.
Another part of our Invention is particularly applicable to steam
engines for compressing air, and it consists in governing the position of
the throttle or other admission valve by admitting air into a cylinder, the
piston of which is connected to the throttle valve or to a valve gear.
When the prssure of the compressed air acts on the piston a spring or
weight is compressed, and the valve is closed, and when the pressure is
reduced the spring or weight again opens the valve.

page_text: 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 1st October 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, GEORGE
HOLCROFT and WILLIAM NATHAN DACK, both of the City of Manchester,
Engineers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the First day of April, in the year of our
Lord One thousand eight hundred and sixty-nine, in the thirty-second
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 license 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 AND
APPLICABLE TO STEAM ENGINES," 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.
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 statement (that is to say):-
Our Invention relates to an improved mode of working the valves of
the steam engines described in the Specification of Letters Patent granted
to us on the Eleventh day of December One thousand eight hundred
and sixty-seven, No. 3512, and consists,---
Firstly. In the application of a balance valve with back plate placed
on a plate or facing behind the ordinary slide valve.

page_text: Secondly. In connecting the differential stop to the eccentric rod or
its equivalent.
Thirdly. In making the governor rod in two parts, each with a head
acted upon by springs contained in a box.
Fourthly. In working the valves of certain ordinary steam engines
by applying a catch to the slide worked to and fro by the eccentric.
Fifthly. In the application of a spiral or screwed shaft, which in
moving endwise varies the position of the cam or eccentric when the
governor balls rise or fall below the usual working range.
Sixthly. In applying cylindrical admission and exhaust valves having
a branched connecting passage to steam engines worked by four valves
or to engines worked by slide valves.
Seventhly. In shutting the throttle or admission valve when the
governor balls owing to an accident suddenly expand or collapse by
causing the sliding bush of the governor to act on the screwed
eccentric or other agent by which the throttle or admission valve is
worked.
Eighthly. In governing the position of the throttle or other admission
valve of steam engines for compressing air by admitting air into a
cylinder the piston of which is connected to the throttle valve or to a
valve gear.
Ninthly. In an improved mode of trussing or staying the entablature
and other parts of beam or vertical engines.
And lastly. In uniting the cylinders of steam engines in which two
steam cylinders are used by four or other convenient number of stay
bolts, thereby avoiding the necessity of prolonging the foundation and
the engine bed.
And in order that our Invention may be fully understood and readily
carried into operation we will proceed to describe the two accompanying
Sheets of Drawings, reference being had to the figures and letters
marked thereon.
On Sheet 1, Figures 1 and 2 are two views of part of a steam engine
to which the first, second, and third improvements above referred to are
applied. a is part of the cylinder of a steam engine, and 6 the crank
shaft with the ordinary eccentrics for working the valves; d is the slide

page_text: valve, and d the back plate made in the manner described in the
Specification of Letters Patent granted to us on the Eleventh day of
December One thousand eight hundred and sixty-seven, No. 3512. On
the back plate d' is the expansion valve c, which is balanced by the
back plate c'. This back plate c' is supported on the back plate d' and
held in contact with it by the spring or other equivalent. By
this means the friction of the expansion valve is reduced.
In the Specification above referred to we described our improved
variable or differential stop as coming in contact with a fixed stop. Now
according to our present improvements we connect the said differential
stop, consisting of the right and left-handed screws g and g' and the
carriage e, to the shackle & forming part of the spindle of the slide
valve thereby rendering the motion of the expansion valve positive,
whereas in the arrangement described in our former Patent it depended
on the friction of one valve on the other. When the end of the screw g¹
is in contact with the buffer or shoulder the governor would not be
able to move the rack h, if the governor rod were solid as described in
the Specification above referred to, but in order to obviate this defect
we now propose to make the governor rod in two parts, as shewn in
Figure 2. The ends of the said parts are provided with heads between
which is the spring h', and between the heads and the ends of the casing
in which they work are the springs h² and . By this means when
the governor rod is raised the springs h2 and 3 are compressed and
ready to act on the rack h the moment the end of the screw g or g¹ is
released from the buffer fe or f³, and when the governor rod is depressed
the spring his compressed and ready to act in the same manner.
Figure 3 is a side view partly in section of the valve gear applied to
a Corliss steam engine; Figure 4 is a plan of part of the same; Figures
5 and 6 are sections of parts of the same. In Figure 3, h, h, are the
admission valves, and h', h¹, are the exhaust valves, which are made in
the ordinary manner. i is the excentric rod for moving the slide j to
and fro; the slide j shewn detached in Figure 4 is provided with side
flanges, shewn best in Figure 6, between which the sliding blocks j¹ fit;
these sliding blocks j' are connected to or disconnected from the slide j
by means of the catches, which are raised by the cams k¹ and drop by
their own weight or by a spring. The sliding blocks j¹ are connected to
the valves h, h, by the links h³, and they are also connected to the
toggle jointed links ³, the weight h' being attached to the centre link

page_text: of the toggle joint. The slide j is connected to the exhaust valves h
by the links h. One of the cams k¹ is provided with a spiral key fitting
in a spiral groove in one of the shafts, as shewn in Figure 5, which
is driven by the wheels ³, one of which is actuated by the engine.
The end of the groved shaft is connected to the governor either
directly or by the hydraulic cylinder *. The two shafts are
connected by a pair of spur wheels shewn in Figure 3.
The mode of operation is as follows:-So long as the engine is at work
the eccentric rod i moves the slide j to and fro, and the links h³ work the
exhaust valves h' as usual. When the catches are down, as shewn in
Figure 3, the sliding blocks j' are also carried to and fro by the block j
to work the valves h, h, but as soon as the excentric ' has lifted the
catch the sliding block j' is instantly brought back by the falling of
the weight which drops into a cup cast to the cylinder and lined with
some soft material to prevent noise. The time at which the cam lifts
the catch is regulated according to the load on the engine by the
governor which moves the shaft endwise, and in so moving the cam
kis turped partly round, and thus varies the time of releasing the
catch. After the catch has been raised it drops on to the side plates j³
and is held up by them until the sliding block returns to its former
position, and allows the catch to drop again into the position shewn.
Figure 7 represents a modification of this part of our Invention. In
this arrangement our improvements are applied to a Corliss engine with
the ordinary wrist plate l. It is obvious that by the means shewn and
described the force required to lift the weight * or to compress a
spring as in the usual mode of closing the valves is applied direct to
the sliding blocks or wrist plate instead of passing through the spindles
of the valves as heretofore.
Figure 8 represents our improved arrangement of steam passages.
a is part of the cylinder, and h and h' are the admission and exhaust
valves. The steam is admitted to the valve h and exhausted from the
valve h' through the branched connecting passage l'. This branched
passage is particularly applicable to engines worked by four valves, but
it may be applied to engines worked by slide valves.
On Sheet 2, Figure 9 represents our improved mode of shutting the
throttle or admission valve of steam engines. In this view m is the
spindle of an ordinary ball governor, and m' the bush which slides up
and down on the spindle. When the governor balls expand or collapse

page_text: beyond their proper limit the bush m' rises or falls and is held in either
position by a spring or other catch connected to the spindle. The throttle
valve is thus closed when the balls expand, or in case of accident to the
governor, by the action of the screwed shaft, above described in
reference to Figure 5, when the balls fall.
Figure 10 is an elevation of our improved apparatus for governing the
position of the throttle or other admission valve of engines employed
for compressing air and for governing the pressure of the air in the
receiver. In this view n is a throttle valve of the ordinary construction.
and o is a cylinder placed above the throttle valve, as shewn in Figure 10,
or connected therewith by rods and levers, as shewn in Figure 11.
Within the cylinder o is the piston o', fixed to the piston rod o³, which
passes through the lid of the cylinder o and is attached to the cross head
The springs p are placed between the lid of the cylinder o and the
piston o¹, and the strength of the springs can be regulated by the weight
on the long arm of the lever p¹. To the cross head o³ is connected the
bridle q, forming part of the spindle r of the throttle valve n. The lower
end of the cylinder o is connected by the pipe 1 with the air receiver.
The piston rod o may be connected to a valve gear. When the air in
the receiver is above the proper limit the pressure of the air raises the
piston o' and compresses the springs p, thereby partially closing the
throttle valve and reducing the speed of the steam engine by which the
air is compressed. The contrary action takes place when the pressure of
air in the receiver is reduced, the throttle valve being then opened
increases the speed of the engine; by this arrangement the air in the
receiver is maintained at a nearly uniform pressure, notwithstanding the
number of furnaces tapped at once.
Figure 12 represents part of a vertical beam engine illustrating our
improved mode of trussing or staying the entablature. s is the ordinary
entablature, below which is the strutt; the tie rods t' take hold of the
beams t below, these beams pass through the walls of the engine house
and into the foundation. The upper ends of the tie rods t¹
pass through
the strutt t, which is connected by the diagonal stays to the entab-
lature s. By this arrangement the weight of the walls is brought to
bear in resisting the lift or upward strain of the engine. This improved
mode of trussing or staying is also applicable to the cylinder and to the
crank shaft.
The last part of our Invention is applicable to steam engines in which

page_text: two steam cylinders are used in line with each other, and it consists in
uniting the cylinders by four or other convenient number of stay bolts,
thereby avoiding the necessity of prolonging the foundation and the
engine bed.
Having thus stated the nature of our Invention, and described the
manner of performing the same; we declare that we claim,-
First. The application of a balance valve with back plate on a plate
or facing behind or upon the ordinary slide valve, as shewn and
described.
Secondly. The application of the differential stop to the eccentric rod
or its equivalent, whereby the motion of the valve is rendered positive
as shewn and described.
Thirdly. Making the governor rod in two parts and connecting them
by springs, as shewn and described.
Fourthly. The application of sliding blocks and slide for working the
valves of steam engines, and the catch k for connecting the sliding
block to the slide, also the application of the weighted toggle joint for
closing the valves of Corliss or similar valve gears, as shewn and
described. We also claim the direct application of the toggle joint
or other agent to the wrist plate or sliding block for closing the
valves.
Fifthly. The application of the spiral or screwed shaft k³, and moving
the same endwise by the governor or by a hydraulic cylinder, in com-
bination with the governor for varying the time of disconnecting the
sliding blocks from the main block of Corliss or other similar valve gear,
as shewn and described.
Sixthly. The branched passage for connecting the admission and
exhaust valves, as shewn and described.
Seventhly. The improved mode of shutting the throttle or admission
valve of steam engines when the governor balls expand or collapse, as
shewn and described.
Eighthly. The application of the cylinder o, which is in communica-
tion with the receiver, whereby the pressure of air in the receiver is
kept nearly uniform and is made to regulate the speed of the steam
engine according to the quantity of air required, as shewn and
described.

page_text: Ninthly. The improved mode of trussing or staying the entablature
and other parts of steam engines, as shewn and described.
And, lastly. The mode of connecting the two steam cylinders of
engines in which the cylinders are in line, as described.
In witness whereof, I, the said William Nathan Dack, have hereto 5
set my hand and seal, this Thirtieth day of September, One
thousand eight hundred and sixty-nine.
W: N. DACK. (L.S.)