IMPROVEMENTS IN STEAM ENGINES
Year: 1872

page_text: LETTERS PATENT to Edward Field, of Chandos Chambers, Adelphi,*
in the County of Middlesex, Consulting Engineer, and Francis
Michael Cotton, of Foulis Terrace, Kensington, in the same County,
Civil Engineer, for the Invention of "IMPROVEMENTS IN STEAM
ENGINES."
Sealed the 7th June 1872, and dated the 5th February 1872.
PROVISIONAL SPECIFICATION left by the said Edward Field and
Francis Michael Cotton at the Office of the Commissioners of
Patents, with their Petition, on the 5th February 1872.
We, EDWARD FIELD, of Chandos Chambers, Adelphi, in the County
of Middlesex, Consulting Engineer, and FRANCIS MICHAEL COTTON,
of Foulis Terrace, Kensington, in the same County, Civil Engineer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
STEAM ENGINES," to be as follows:
:-
This Invention has for its object improvements in steam engines. It
relates principally to engines of the kind known as compound high and

page_text: low pressure steam engines in which high pressure steam is made to do
duty first in a high-pressure cylinder, and thence passes into a second or
low-pressure cylinder, wherein it expands and acts upon another piston,
and our improvements are partly applicable also to engines of other
kinds.
According to this Invention we arrange a reciprocating high-pressure
cylinder or chamber wholly within a low-pressure cylinder or chamber
with their axes parallel to each other, the two cylinders being by
preference concentric. The high-pressure cylinder forms the piston
of the low-pressure cylinder or is connected to the said piston, and
moves with it entirely within the low-pressure cylinder or chamber.
The piston of the high-pressure cylinder is fixed and maintains a
constant position relatively to the low-pressure cylinder.
On starting the engine its first stroke is effected by high-pressure
steam entering the high-pressure cylinder, and exerting its influence
between one end of that cylinder and its fixed piston, thereby moving
the high-pressure cylinder and low-pressure piston towards one end of
the low-pressure cylinder; the high-pressure steam whereby this first
stroke has been effected then passes directly into this same end of the
low-pressure cylinder, and a fresh supply of high-pressure steam enters
the other end of the high-pressure cylinder, so that the high-pressure
cylinder and low-pressure piston are caused to perform their second or
return stroke by the combined action of the expanding steam in the
low-pressure cylinder and of the high-pressure steam in the high-
pressure cylinder, thus completing the first double stroke or revolution
of the engine. The subsequent strokes are effected similarly to the
second or return stroke just mentioned by the combined action of high-
pressure steam from the high-pressure cylinder expanding into the
low-pressure cylinder, and of fresh supplies of high-pressure steam
admitted into the high-pressure cylinder at each stroke as described,
the expanded steam, after having done duty in the low-pressure
cylinder during each stroke, being exhausted therefrom or conveyed to
the condenser during the next or return stroke.
In order to regulate the admission and emission of the steam to and
from the respective cylinders as aforesaid we employ valves of any
suitable construction, arranged to be worked either mechanically or by
steam, or by mechanical means and steam combined.

page_text: We prefer to arrange the valves within a suitable valve chamber
formed in the body or casting of the above-described combined high-
pressure cylinder and low-pressure piston, and furnished with suitable
ports, passages, or ways which are opened and closed as required by the
3 said valves. These valves according to one arrangement are moved by
steam, admitted into or retained in the ends of the low-pressure cylinder,
acting on small pistons which act as valves for opening and closing the
communication between the high-pressure cylinder and the low-pressure
cylinder, and are also connected with other valves for regulating the
exhaust. These small pistons work one within each end of the valve
chamber, which is made cylindrical by preference, and communicates
near each end with the interior of the high-pressure cylinder and with
the corresponding end of the low-pressure cylinder, thereby forming
a short passage or way between the two cylinders at their respective
ends, the communication being opened and closed as required by the
movement of the small pistons. One of the faces of each small piston
is wholly exposed to the action of the steam for the time being in the
corresponding end of the low-pressure cylinder; so that the pressure of
the steam in the low-pressure cylinder by moving the small piston
changes the positions of the exhaust valves, and this small piston itself
simultaneously establishes the communication whereby the high-pressure
steam passes directly by the valve chamber from the high-pressure
cylinder into the same end of the low-pressure cylinder.
In some cases it may be found advisable to employ more than one
cylindrical valve chamber provided with valves and small pistons as
described, and such valves and small pistons may in some cases be
actuated by mechanical means.
The combined high-pressure cylinder and low-pressure piston is
provided between its ends or covers with ribs, feathers, or pieces, which
may be formed by coring out the exterior portion of the casting
longitudinally for the greater part of its length. These ribs, feathers,
or pieces serve as steam-tight partitions fitting steam tight against the
inner surface of the low-pressure cylinder, thus forming chambers
between the two cylinders into which steam from the boiler constantly
flows for supplying the bigh-pressure cylinder and other similar chambers
through which the exhaust steam escapes. Just before the low-pressure
piston terminates its stroke at either end a small supply of high-pressure
steam from the above-mentioned steam chambers is admitted into the

page_text: end of the low-pressure cylinder towards. which the low-pressure piston
is advancing, which steam forms an efficient cushion and also moves
the small piston at that end to establish the communication between the
high-pressure cylinder and the low-pressure cylinder. Or the necessary
movement of the small piston may be effected by the steam which may
have been retained in the end of the low-pressure cylinder (after doing
duty therein) to form a cushion for the low-pressure piston.
In some cases we may dispense with the ribs, feathers, or pieces above
described, and in addition to the small pistons for establishing the
communication between the high and low pressure cylinders, provide
other pistons or valves in a separate valve chamber arranged longi-
tudinally or otherwise outside of the low-pressure cylinder for opening
and closing the exhaust passages from the low-pressure cylinder, such
additional pistons or valves being moved by steam or mechanical means.
Or we may form the ports, passages, or ways communicating with the
high-pressure cylinder through the rod of the fixed high-pressure piston,
providing other ports, passages, or ways for the low-pressure cylinder, so
that the ports, passages, or ways leading to the respective ends of both
cylinders and to the steam supply and exhaust may be opened and closed
as required by suitable valves which we by preference arrange on the
cover of the low-pressure cylinder, and actuate partly by mechanical
means and partly by steam.
In direct-acting double engines according to our Invention each low-
pressure piston may be arranged to commence its stroke on or before the
arrival of the other low-pressure piston at the middle of its stroke, for
which purpose we provide each pair of one high-pressure and one low-
pressure cylinders with a hollow main steam slide containing an auxiliary
slide working within it; the object of the auxiliary slide being to admit
steam into the hollow main steam slide for completing the stroke of the
latter, and thereby reversing the action of the steam in its cylinders.
Each hollow main steam slide is actuated by a twisted bar, an incline,
or equivalent device, which also communicates motion to the auxiliary
slide of the other hollow main steam slide, so that the piston of each
low-pressure cylinder gives the necessary motion through its rod to the
twisted bar or equivalent device for actuating its own main steam slide
and the auxiliary slide of the other main steam slide.
This method of regulating the admission and emission of steam to
and from the cylinders of direct-acting double cylinder compound high.

page_text: and low-pressure steam engines, by providing each cylinder with a
hollow main steam slide containing an auxiliary slide, and causing the
piston of one cylinder to actuate its own main steam slide and the
auxiliary slide of the other cylinder's main steam slide, may be ad-
vantageously applied to direct-acting double cylinder steam engines of
other kinds for use in steam fire engines and for other purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Edward Field and Francis Michael Cotton in the
Great Seal Patent Office on the 5th August 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, EDWARD
FIELD, of Chandos Chambers, Adelphi, in the County of Middlesex,
Consulting Engincer, and FRANCIS MICHAEL COTTON, of Foulis Terrace,
Kensington, in the same County, Civil Engineer, send greeting..
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of February, in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give.
and grant unto us, the said Edward Field and Francis Michael Cotton,
Her special licence that we, the said Edward Field and Francis Michael
Cotton, our executors, administrators, and assigns, or such others as we,
the said Edward Field and Francis Michael Cotton, 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 "IMPROVEMENTS IN
STEAM ENGINES," upon the condition (amongst others) that we, the said
Edward Field and Francis Michael Cotton, our executors or adminis-
trators, by an instrument in writing under our or their hands and seals,
or under the hand and seal 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 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: supplies of high-pressure steam admitted into the high-pressure cylinder a
at each stroke as described, the expanded steam, after having done duty
in the low-pressure cylinder 6 during each stroke, being exhausted there-
from or conveyed to the condenser during the next or return stroke.
The combined high-pressure cylinder and low-pressure piston a is pro-
vided between its ends or covers a¹, a², with ribs, feathers, or pieces a³,
which may be formed by coring out the exterior portion of the casting
longitudinally for the greater part of its length. These ribs, feathers, or
pieces as serve as partitions fitting steam tight (by means of suitable
packing at a*) against the inner surface of the low-pressure cylinder b,
thus forming chambers' f (connected by the passage f²) between the two
cylinders, into which steam from the boiler constantly flows by the
inlet for supplying the high-pressure cylinder a, and other similar
chambers he (connected by the passage 7), through which the exhaust
steam escapes, as shewn in Fig. 2. Just before the low-pressure piston a
terminates its stroke at either end, a small supply of high-pressure steam
from the above-mentioned steam chambers f is admitted by the groove
or channel g (formed in the cylinder. 6) into the end of the low-pressure
cylinder b, towards which the low-pressure piston a is advancing, which
steam forms an efficient cushion, and also moves the small piston valve
at that end to establish the communication between the high-pressure
cylinder a and the low-pressure cylinder b.
The admission and emission of steam to and from the respective
cylinders is regulated by piston valves d, d', d³, d³, connected togetlier by
a spindle d*, and working within a suitable valve chamber e, formed
in the body or casting of the above-described combined high-pressure
cylinder and low-pressure piston a, and furnished with suitable ports,
passages, or ways, which are opened and closed as required' by the said
valves. The high-pressure cylinder a is arranged' to communicate with
the low-pressure cylinder 6 at one end by the port h and part e¹ of the
valve'chamber e, and' at the other end, by the port h¹ and part e² of the
valve chamber e. The valve chamber is placed in communication with
the steam chambers f by the ports' h², h³. The ports h, k, formed in the
high-pressure cylinder a conduct the exhaust steam from the respective
ends of the low-pressure cylinder 6 into the valve chamber e, whence it
escapes by the exhaust h. The piston valves d, d³, d³, d³, are moved by
steam admitted alternately into the respective ends of the low-pressure
cylinder b, and acting on the small pistons d, d³, which act as valves for

page_text: opening and closing the communication between the high-pressure
cylinder a and the low-pressure cylinder b, and are also connected
with the other valves d³, d², for regulating the exhaust. The small
pistons d, d, work one within each end of the valve chamber e, which
is made cylindrical and communicates near each end with the interior of
the high-pressure cylinder a and with the corresponding end of the low-
pressure cylinder b, thereby forming a short passage or way as described
between the two cylinders at their respective ends, the communication
being opened and closed as required by the movement of the small
pistons d, d³. One of the faces of each small piston d, d³, is wholly
exposed to the action of the steam for the time being in the corre-
sponding end of the low-pressure cylinder b. The Drawing shows the
position of the parts which obtains when the low-pressure piston a has
moved nearly to the end of the low-pressure cylinder b, and has thereby
first closed the exhaust port h* by the part a¹ of the low-pressure piston a
entering the recess b¹ in the cover of the low-pressure cylinder, and sub-
sequently opened a communication by the groove or channel g between
the end 6* of the low-pressure cylinder and the steam chamber f, thereby
admitting steam into the low-pressure cylinder to form a cushion for its
piston a, which steam is supposed to be about throwing the valves over
by acting on the face of the valve d. The effect of so throwing over the
valves will be as follows:- -The high-pressure steam, which has just done
duty in the cylinder a, will pass directly from the end as by the port h
and part e¹ of the valve chamber into the end 6 of the low-pressure
cylinder b, the port h' will be closed by the valve d, the port h³ will be
opened by the valve d², so that the expanded steam will escape by the
port h³ and valve chamber e from the end 63 of the low-pressure cylinder
to the exhaust hº, and the port h³ will be opened by the valve d³, so that
fresh high-pressure steam from the chambers will enter the end a
of the high-pressure cylinder by the ports h³ and h to effect the return
stroke. e³ are partitions through which the valve rod d* works steam
tight. These partitions divide the valve chamber e into three com-
partments, thereby forming steam cushions to receive the shock of the
valves when thrown over. The tappets d** are for the purpose of moving
the valves by hand in the event of their sticking.

page_text: distance between the ends or covers a¹, a³, of the high-pressure cylinder a,
the longitudinal ribs a³ forming the steam-tight partitions. In other
respects this engine resembles that already described.
When the engines above described are constructed to work without
cranks and fly wheels the low-pressure cylinder may be provided at each
end with a steam stop-cock communicating with the boiler for the
purpose of admitting high-pressure steam into the low-pressure"
cylinder to blow over the low-pressure piston a in the event of its
sticking.
distance between the ends or covers a¹, a³, of the high-pressure cylinder a,
the longitudinal ribs a³ forming the steam-tight partitions. In other
respects this engine resembles that already described.
When the engines above described are constructed to work without
cranks and fly wheels the low-pressure cylinder may be provided at each
end with a steam stop-cock communicating with the boiler for the
purpose of admitting high-pressure steam into the low-pressure
cylinder to blow over the low-pressure piston a in the event of its
sticking.
Fig. 6 (Sheet 2) is a plan view, partly in section, of an engine in
which the valves are worked by mechanical means.
Fig. 6° is a skeleton side view of the crank arrangement for working
the valves.
Fig. 7 is a transverse section taken in the line G, H, of Fig. 6. In
this arrangement the grooves or channels 9 described with reference to
previous Figures are dispensed with. The valve rod d* passes through
a suitable stuffing box i in the low-pressure cylinder cover 6*, and is
connected by a connecting rod d* to a pin k¹ carried by a crank plate /*
attached to the main crank pin k, the pin k¹ being set slightly in advance
of the pin k, but having by preference the same throw.
The operation of this arrangement is as follows:-As shewn in Fig. 6
the combined high-pressure cylinder and low-pressure piston a has
reached the end of its stroke. The port his closed by the valve d¹.
The valve d has begun to open the port h for the passage of the high-
pressure steam from the cylinder a into the end 6% of the low-pressure
cylinder b. The valve d² has commenced opening the exhaust port h³
for the escape of the expanded steam from the end 68 of the low-pressure
cylinder to the exhaust h', and the valve d³ has commenced opening the
port h¹ to admit high-pressure steam from the chamber f by the ports h³
and h¹ to the end as of the high-pressure cylinder a. By the continued
movement of the crank the valves are caused to complete the opening
of the ports h, h³, and h¹. By setting. the pin k' in advance of the main
crank pink, as described, we obtain a maximum amount of motion at
the ends of the stroke when the valves require to be reversed, and a
minimum amount of motion throughout the rest of the stroke when the
ports are completely open. The point at which steam is cut off in the

page_text: u is the exhaust for both cylinders; n is the main slide of cylinder
No. 1; o is the auxiliary slide of the main slide n, within which it
works as shewn; p is the main slide of cylinder No. 2; q is the auxiliary
slide of the main slide p, within which it works as shewn. The main
slide n and the auxiliary slide q receive their motion from a twisted
bar z, which twisted bar is worked by a cross head z¹ attached to the
piston rod of cylinder No. 1. The main slide p and the auxiliary slide o
receive their motion by means of another twisted bar 28. This twisted
bar is worked by a cross head z³ attached to the piston rod of cylinder
No. 2.
The action of this arrangement is as follows:-The piston of cylinder
No. 2 on arriving at the end of its stroke will have actuated the twisted
bar attached to its piston rod in such manner as to cause the main steam
slide p to close the main steam port t¹, as shewn in Fig. 11. At this.
moment the piston of cylinder No. 1 will have reached or nearly reached
the middle of its stroke, and by means of the twisted bar z will have
brought the port v² (drilled up the rod q¹ of the auxiliary slide q) into
communication with the port v. This port communicates with the
port ¹ by means of the port v³, which is formed in the casting / as
shewn in Fig. 14. Consequently when the port v¹ is in communication
with the port v, as above described, steam will be admitted into the
interior of the main slide p at the end p¹, thus blowing over the main
slide P and completing its stroke. While this is taking place the port w¹
(also drilled up the rod q¹) will be brought into communication with the
port 1. This port w communicates with the port & through the port w³
which is formed in the casting 7, as shewn in Fig. 14.
The port w being in the above-named position the steam will be
exhausted from the end p² of the slide p. By this action steam will be
admitted to the reverse end of cylinder No. 2, and its piston will there-
upon commence.its: return stroke. During this return stroke its twisted
bar z will actuate the main slide p and the auxiliary slide o, so that
when the piston reaches or nearly reaches the centre of its stroke it will
have brought the port x¹ (drilled up the rod o' of the auxiliary slide o)
into communication with the port x. This port x communicates with
the port t through the port a formed in the casting 1. At this time the
piston of cylinder No. 1 will have reached the end of its stroke, and the
port will have been closed by the main slide n actuated by the twisted.
The port having been brought into communication with the
bar .

page_text: port as above explained, steam will now be travelling from the port t
through the ports x2, x, and x¹, into the end n¹ of the main steam
slide n to blow it over and complete its stroke, and the steam from the
end n³ will be escaping by the ports y¹, y, and y²; y² being the port
through the body of the jacket which joins y with t¹.
The continued action of the engine will be as above explained, the
piston of each cylinder bringing itself to rest by its own main steam
slide, and just previously moving the auxiliary slide of the other cylinder
to complete the movement of its main steam slide. To enable either
piston to commence its stroke on or before the arrival of the other piston :
at the middle of its stroke we give to the ports o¹, w¹, x³, and y¹, a slight
lead, or in other words arrange them to communicate with the ports
v, w, x, and y respectively, before either piston has arrived at the
middle of its stroke in order that the main steam slides may be fairly
thrown over and the steam in the one cylinder reversed by the time the 1
piston of the other cylinder has arrived at the middle of its stroke. It
will be understood that the engine shewn in Fig. 15 is not a compound
engine.
Having described our said Invention of "Improvements in Steam
Engines," and having explained the manner of carrying the same into 2
practical effect, we hereby declare that we lay no claim to the several
parts herein-before described and referred to except when the same are
used in and for our said Invention, which we hereby declare to consist
in,—
First. The construction of steam engines in which a combined high- 2
pressure cylinder and low-pressure piston works wholly within the low-
pressure cylinder, a steam chamber (or steam chambers) being formed
between the two cylinders, whence steam is supplied alternately to the
respective ends of the high-pressure cylinder, and is from thence ex-
hausted directly into the same ends of the low-pressure cylinder as above 3
described.
Secondly. The construction of engine shewn in and described with
reference to Figs. 1, 2, 3, and 4 of the accompanying Drawings.
Thirdly. The construction of engine shewn in and described with
reference to Fig. 5 of the accompanying Drawings.
Fourthly. The construction of engine shewn in and described with
reference to Figs. 6, 6º, and 7 of the accompanying Drawings.
3

page_text: Fifthly. The construction of engine shewn in and described with
reference to Figs. 8, 9, and 10 of the accompanying Drawings.
Lastly. The construction of direct-acting double cylinder steam
engines in which each cylinder is provided with a hollow main steam
slide containing an auxiliary slide, the piston of each cylinder actuating
its own main steam slide, and the auxiliary slide of the other cylinder's
main steam slide as shewn in and described with reference to Figs. 11,
12, 13, 14, and 15 of the accompanying Drawings.
In witness whereof, we, the said Edward Field and Francis Michael
Cotton, have hereunto set our hands and seals, this Third day
of August, in the year of our Lord One thousand eight hundred
and seventy-two.
5 Witness,
W. LLOYD WISE,
Patent Agent,
EDWARD FIELD.
(L.S.)
FRANCIS M. COTTON. (L.S.)
London.