IMPROVEMENTS IN STEAM ENGINES
Year: 1874

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."
Scaled the 9th October 1874, and dated the 15th July 1874.
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 15th July 1874.
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:-
In the Specification of Letters Patent granted to us the 5th day of
February, 1872, No. 365, there is described a compound steam engine

page_text: in which a combined high-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 thence exhausted directly into the same ends of the
low-pressure cylinder. Our present Invention has reference more
especially to engines of this class when constructed with piston valves
for regulating the admission and emission of steam to and from the
respective ends of the cylinders.
The first part of our Invention relates to arresting the travel of the
piston valves by admitting behind them steam of the same pressure as
that by which they are being impelled, thus placing the valves in
equilibrium. For this purpose we form a groove, recess, or passage (or
grooves, recesses, or passages), in the valve casing in such manner as
when the valve approaches the end of its stroke to establish commu-
nication between the parts of the casing situated at the respective ends of
the valve, thereby admitting steam behind the valve to arrest its farther
progress without any violent concussion. In some cases the necessary
steam may be fed to the recess in the valve casing through passages or
ways formed in the valve spindle or body.
In some cases we arrange for a continuous communication through
the valve, body, or stem between the two ends or faces of the valve.
Thus steam passes behind the valve between it and the block, the move-
ment of the valve being due to the difference between the areas against
which the steam acts on its respective faces. Towards the end of
the stroke the passage in the valve body or chamber is automatically
closed, thus forming a cushion which ultimately brings the valve to
rest.
In order to ensure the effectual closing at the proper times of the
communication between the high and low-pressure cylinder, and to
provide for wear of the peripheries of the piston valves we suitably
face the outer ends of the valves and cause them to close against
suitable seats or facings in the valve casing on the completion of each
stroke.
Another part of our Invention relates to modifying the impulse given
to the low-pressure piston at the commencement of each stroke by the
steam exhausted from the high-pressure cylinder, so as to attain greater

page_text: uniformity of speed throughout the stroke of the low-pressure piston.
To this end we provide the low-pressure piston (which contains the high-
pressure cylinder) and the low-pressure cylinder, with arrangements
whereby at the commencement and during the earlier portion of each
stroke the steam escaping from the high-pressure cylinder is throttled on
its way to the low-pressure cylinder by a contraction of the area or partial
obturation of the passage or way, establishing communication between
the two cylinders, such passage or way being automatically opened to
its full extent after a certain portion of the stroke has been accom-
plished.
Lastly, our Invention consists in adapting our aforesaid patent engines
to work on the double expansion principle; that is, arranging them so
that the supply of steam to the high-pressure cylinder may be cut off
before the completion of the stroke, thus enabling the high-pressure
steam to be expanded in the high-pressure cylinder as well as afterwards
in the low-pressure cylinder. For this purpose we divide the steam
space between the high and low pressure cylinders into two com-
partments or chambers, one considerably larger than the other, and
we provide a separate branch pipe for conducting steam into each
of these compartments or chambers from the main steam pipe or
boiler.
The larger compartment or chamber serves as a steam jacket or casing
to the high-pressure cylinder, the smaller compartment or chamber is by
the action of the valves placed in communication at the proper times
with the piston of the high-pressure cylinder so as to feed high-pressure
steam thereto, the supply of which is cut off at any desired point of the
stroke by a valve, cock, or equivalent arrangement actuated by a moving
part of the engine for that purpose.
It will be evident that parts of our Invention as herein described,
besides being applicable to engines of the kind described in the Specifi-
cation of our former Patent herein-before referred to, may be applied
also to engines of other constructions.

page_text: 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 13th January 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, wc, 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, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of July, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
eighth 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 license 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 administrators, by an instrument in writing
under our, or their, or one of our or their hands and seals, should par-
ticularly 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 Edward Field and Francis Michael
Cotton, 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
and the Drawings therein referred to (that is to say) :-
In the Specification of Letters Patent granted to us the 5th day of
February 1879 No 26% than in

page_text: in which a combined high-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 thence exhausted directly into the same ends of the low-
pressure cylinder. Our present Invention has reference more especially
to engines of this class when constructed with piston valves for regu-
lating the admission and emission of steam to and from the respective
ends of the cylinders.
The first part of our Invention relates to arresting the travel of the
piston valves by admitting behind them steam of the same pressure as
that by which they are being impelled, thus placing the valves in
equilibrium, or approximately so. For this purpose we form a groove,
recess, or passage (or grooves, recesses, or passages) in the valve casing
in such manner, as when the valve approaches the end of its stroke to
establish communication between the parts of the casing situated at the
respective ends of the valve, thereby admitting steam behind the valve
to arrest its farther progress without any violent concussion. The
necessary steam is fed to the recess in the valve casing through passages
or ways formed in the valve body.
In some cases we arrange for a continuous communication through
the valve body or stem between the two ends or faces of the valve.
Thus steam passes behind the valve between it and the block, the
movement of the valve being due to the difference between the areas
against which the steam acts on its respective faces. Towards the end
of the stroke the passage in the valve body or chamber is automatically
closed, thus forming a cushion which ultimately brings the valve to
rest.
Secondly. In order to ensure the effectual closing at the proper times
of the communication between the high and low-pressure cylinders,
and to provide for wear of the peripheries of the piston valves, we
suitably face the outer ends of the valves and cause them to close
against suitable seats or facings in the valve casing on the completion of
each stroke.
The third part of our Invention relates to modifying the impulse
given to the low-pressure piston at the commencement of each stroke
by the steam exhausted from the high-pressure cylinder, so as to attain

page_text: greater uniformity of speed throughout the stroke of the low-pressure
piston. To this end we provide the low-pressure piston (which contains
the high-pressure cylinder) and the low-pressure cylinder with arrange-
ments, whereby at the commencement and during the earlier portion of
each stroke, the steam escaping from the high-pressure cylinder is
throttled on its way to the low-pressure cylinder by a contraction of
the area or partial obturation of the passage or way establishing com-
munication between the two cylinders, such passage or way being
automatically opened to its full extent after a certain portion of the
stroke has been accomplished.
Lastly. Our Invention consists in adapting our aforesaid Patent
engines to work on the double expansion principle; that is, arranging
them so that the supply of steam to the high-pressure cylinder may bo
cut off before the completion of the stroke, thus enabling the high-
pressure steam to be expanded in the high-pressure cylinder as well as
afterwards in the low-pressure cylinder. For this purposs we divide the
steam space between the high and low-pressure cylinders into two
compartments or chambers, one considerably larger than the other,
and we provide a separate branch pipe for conducting steam into each
of these compartments or chambers. from the main steam pipe or
boiler.
The larger compartment or chamber serves as a steam jacket or casing
to the high-pressure cylinder; the smaller compartment or chamber is
by the action of the valves placed in communication at the proper times
with the piston of the high-pressure cylinder so as to feed high-pressure
steam thereto, the supply of which is cut off at any desired point of the
stroke by a valve, cock, or equivalent arrangement actuated by a moving
part of the engine for that purpose.
It will be evident that parts of our Invention, as herein described,
besides being applicable to engines of the kind described in the Specifi-
cation of our former Patent, herein-before referred to, may be applied
also to engines of other constructions.
Such being the nature of our Invention, we proceed to describe the
manner in which we prefer to carry it into practical effect, as illustrated
in the accompanying Sheets of Drawings, premising that the first,
second, and third parts of our Invention are applicable to reciprocating
crankless engines only, and the last part to crank engines only.

page_text: them and the block g, the movement of the valves f being due to the
difference between the areas, against which the steam acts on the
respective faces of the valves. Towards the end of the stroke the
passages are alternately closed automatically, thus forming cushions
which ultimately bring the valves to rest.
In some cases we provide for the formation of steam cushions by
placing the recesses a slightly in advance of the blocks g*. In this way
steam cushions will be formed which will ensure the arrest of the move-
ments of the valves.
To modify the impulse given to the low pressure piston i (which
constitutes also the high-pressure cylinder) at the commencement of
cach stroke by the steam exhausted from its interior so as to attain
greater uniformity of speed throughout the stroke of the said low-
pressure piston by throttling the steam escaping from the high-pressure
cylinder i on its way to the low-pressure cylinder %, we, according to one
arrangement (shewn in Figs. 1, 2, and 4), provide the covers of the low-
pressure cylinder with plugs (or projections) arranged to enter the
passages m of the high-pressure cylinder. Thus the area of the passage
or way establishing communication between the two cylinders is con-
tracted or partially obturated during the earlier portion of each stroke of
the low-pressure piston, and is gradually opened automatically to its full
extent after a certain portion of the stroke has been accomplished.
Instead of tapering the plugs, as shewn, the gradual opening of the
passages or ways may be effected by forming in the plugs grooves of
gradually increasing sectional area, or the passages m may be tapered.
In another arrangement (Fig. 5) the same result is attained by pro-
viding the escape orifices m of the high-pressure cylinder i with tubes,
nozzles, or extensions n arranged to enter tapered recesses or chambers o
formed in or attached to the covers of the low-pressure cylinder k.
Instead of tapering the recesses or chambers o they may be made parallel,
the tubes, nozzles, or extensions n being formed with slots or openings,
as will be readily understood.
It will be evident that this part of our Invention may be carried out
in other forms than those illustrated, and that other constructions of
compound engines working without cranks may be provided with
arrangements for contracting or partially obturating during the earlier
portion of each stroke, and gradually opening the passages or ways

page_text: establishing communication between the high and low-pressure
cylinders.
In Fig. 4 is shewn the manner in which we ensure the effectual
closing of the communication between the high-pressure cylinder and
the low-pressure cylinder, and provide for wear of the peripheries of the
piston valves. The outer end of each valve f is faced and arranged to
close against a seat or facing in the valve casing on the completion of
cach stroke. We sometimes apply this improvement to the exhaust
valves.
In Figs. 6 and 7, which shew the manner of carrying out the last
part of our Invention relating to the working our compound engines on
the double expansion principle, p is the larger steam compartment or
chamber between the high and low-pressure cylinders. It is fed with
steam from the boiler through the passage p¹ and serves as a steam
jacket or casing to the high-pressure cylinder i. The smaller compart-
ment or chamber q fed by the passage q' is by the action of the valves f
placed in communication at the proper times with the piston of the
high-pressure cylinder i so as to feed high-pressure steam thereto, the
supply of which is cut off at any desired point of the stroke by a valves,
actuated for that purpose by a moving part of the engine, as will be
readily understood.
Having described the nature of our said Invention of "Improvements
in Steam Engines," and having explained the manner of carrying the
same into practical effect, we hereby declare what we consider to be
novel and original, and therefore claim as the Invention secured to us
by the herein-before in part recited Letters Patent to be,-
First. In direct-acting compound engines, having steam moved piston
valves, arresting the travel of such valves by admitting behind them
steam of the same pressure as that by which they are being impelled,
such steam being fed to the spaces behind the valves through passages
or ways formed in the valve bodies, substantially as herein-before
described and illustrated.
Secondly. In direct-acting compound engines, having steam moved
piston valves, the facing the outer ends of such valves and arranging
them to close against seats or facings in the valve casing on the com-
pletion of each stroke, as herein-before described with reference to Fig. 4
of the accompanying Drawings.

page_text: Thirdly. The arranging crankless compound engines to throttle the
stcam passing from the high-pressure cylinder to the low-pressure
cylinder during the earlier portion of each stroke by contraction of the
areas or partial obturation of the passages or ways establishing communi-
cation between the high and low-pressure cylinders, such passages or
ways being gradually opened automatically to the full extent after a
certain portion of the stroke has been accomplished.
Fourthly. The improved construction of direct-acting compound
engine, shewn in and described with reference to Figs. 1, 2, and 3 of the
accompanying Drawings.
Fifthly. The arrangement and construction of compound engines, as
described with reference to Figs. 6 and 7 of the accompanying Drawings,
to enable the high-pressure steam to be expanded in the high-pressure
cylinder as well as afterwards in the low-pressure cylinder.
In witness whereof, we, the said Edward Field and Francis Michael
Cotton, have hereunto set our hands and scals, this Ninth day
of January, in the year of our Lord One thousand eight hundred
and seventy-five.
EDWARD FIELD.
(L.S.)
FRANCIS MICHAEL COTTON. (L.S.)
Witness,
F. J. BROUGHAM,
Clerk to Mr. W. Lloyd Wise,
Patent Agent,
Chandos Chambers,
Adelphi,
London, W.C.