IMPROVEMENTS IN LOCOMOTIVE STEAM ENGINES
Year: 1857

page_text: LETTERS PATENT to Thomas Yarrow, of Arbroath, in the County of
Forfar, North Britain, Engineer, for the Invention of "IMPROVEMENTS IN
LOCOMOTIVE STEAM ENGINES."
PROVISIONAL SPECIFICATION left by the said Thomas Yarrow at the
Office of the Commissioners of Patents, with his Petition, on the 18th
March 1857.
I, THOMAS YARROW, of Arbroath, in the County of Forfar, North Britain,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE
MENTS IN
IN LOCOMOTIVE STEAM ENGINES," to be as follows, that is to say:--
This Invention relates to certain improvements in the consumption or pre-
vention of smoke, and the economising the consumption of fuel, as also to other
improvements in locomotive and stationary engines, so that coal alone can be
used in locomotives.
The improvements consist of a modified form of fire box or furnace, and of
a mode of admitting air to increase the draught, thereby causing the smoke
to be consumed. When applied to locomotive engines, it is proposed to employ
a horizontal midfeather rivetted to the tube plate and sides of fire box, and
gradually extending in an oblique direction upwards towards the furnace door,
[Price 8d.]

page_text: leaving a suflicient space for the passage of the flame, which passage is divided
on the top of the midfeather into a number of cells or flues by means of flue
covers or tiles set on edge, which tiles are covered on the top with the flue cover
as an upper bridge.
For the purpose of supplying the fuel with hot air, pipes are introduced to
run through the ash pan with trumpet mouths placed in front of the ash pan,
the other end opening into a cast-iron chamber or box placed round the fire door,
or the fire bar frame may be so constructed as to allow air to pass through it
into the cast-iron chamber before mentioned. The heated air from this box
passes into.or over the fuel by means of an annular aperture round the fire door,
and if desirable through a series of tubes of hollow stays which communicate
between the hot air box and the fire box.
An arrangement is employed for shaking the fire bars, whereby the clinkers
are destroyed, and the necessity of pricking the bars is obviated. This part of
the Invention consists of a transverse rocking shaft fitted with a number of
short arms, upon each of which rests one end of each alternate fire bar;
a longer arm or lever extending from the opposite side of the rocking shaft
with a rod attached is accessible to the engineman, so that he can shake the
bars when necessary, thereby breaking the clinkers. For the purpose of
economising fuel two distinct arrangements of apparatus are used.
First, a chamber or condenser is fitted up to act as follows:--A valve box
is placed beneath the exhaust pipe of the cylinder, and when the engine
exhausts it lifts this valve, thereby admitting a quantity of steam, which is con-
ducted from the clack box into the chamber or condenser which is placed
beneath the foot plate of the engine, or at any other convenient part of the
engine, with a cock to regulate the necessary quantity of steam required. The
steam so conducted into this chamber or condenser is to heat the water prior
to its being pumped into the boiler, and acts as follows:-The steam passes
through pipes from the valve box beneath the exhaust pipe of the cylinder
into the bottom of the chamber or condenser, which chamber has also another
valve placed on it to prevent the water from running down the pipe. Half
way up the condenser there is a plate bored with a multiplicity of water jet
holders, so that when the water is turned on from the tender it rushes onwards
through these holes, and coming in contact with the exhaust steam admitted
as above described, condensation takes place, and the water becomes heated to
a great extent. To the bottom of the condenser the feed pipe of the pump is
attached, and of course this heated water is pumped into the boiler.
Second, in further economising fuel an apparatus is applied to serve two

page_text: purposes, namely, to prevent to a great extent all waste steam from blowing
into the atmosphere from the safety valves, and also to serve as a steam
pressure guage. If applied only to save the waste steam a common valve will
suffice, but if intended to serve both purposes there is applied a cylinder with
a solid piston, equal to any number of inches area required, with a spring
above the piston to cause the necessary pressure upon the square inch, with a
four or six inch range, which is divided into pounds. When the steam
pressure becomes greater than the working pressure fixed upon, the piston
ascends and the steam passes through an aperture in the cylinder, and is then
conducted into the tender, thereby saving or preventing the steam from
heing wasted, and of course heating the water in the tender to a great
extent.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Yarrow in the Great Seal Patent Office on the 18th
September 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
YARROW, of Arbroath, in the County of Forfar, North Britain, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of March, in the year of our Lord
One thousand eight hundred and fifty-seven, in the twentieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Thomas Yarrow, Her special license, that I, the said Thomas Yarrow, my
executors, administrators, and assigns, or such others as I, the said Thomas
Yarrow, my executors, administrators, or 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
IN LOCOMOTIVE
Islands, and Isle of Man, an Invention for "IMPROVEMENTS
STEAM ENGINES," upon the condition (amongst others) that I, the said
Thomas Yarrow, by an instrument in writing under my hand and seal, 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 I, the said Thomas Yarrow, do hereby declare the
nature of my said Invention, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement
in writing, reference being had to the accompanying Drawings, and to the letters
and figures marked thereon, that is to say: -
My said Invention relates to certain improvements in the consumption or pre-
vention of smoke, and the economising the consumption of fuel, as also to other
improvements in locomotive and stationary engines, so that coal alone can be
used in locomotives.
The improvements consist of a modified form of fire box or furnace, and of a
mode of admitting air to increase the draught, thereby causing the smoke to be
consumed. When applied to locomotive engines, it is proposed to employ a
horizontal midfeather, riveted to the tube plate and sides of the fire box, and
gradually extending in an oblique direction upwards towards the furnace door,
leaving a sufficient space for the passage of the flame, which passage is divided
on the top of the midfeather into a number of cells or flues by means of flue
covers or tiles set on edge, which tiles are covered on the top with a fluc cover
as an upper bridge.
For the purpose of supplying the fuel with hot air, pipes are introduced to
run through the ash pan with trumpet mouths placed in front of the ash pan,
the other end opening into a cast-iron chamber or box placed round the fire
door; or the fire bar frame may be so constructed as to allow air to pass
through it into the cast-iron chamber before mentioned. The heated air from
this box passes into or over the fuel by means of an annular aperture round the
fire door, and if desirable through a series of tubes or hollow stays which com-
municate between the hot air box and the fire box.
An arrangement is employed for shaking the fire bars, whereby the clinkers
are destroyed, and the necessity of pricking the bars is obviated. This part of
the Invention consists of a transverse rocking shaft fitted with a number of
short arms, upon each of which rests one end of each alternate fire bar; a
longer arm or lever extending from the opposite side of the rocking shaft with
a rod attached is accessible to the engineman, so that he can shake the
bars when necessary, thereby breaking. the clinkers. For the purpose of
economising fuel two distinct arrangements of apparatus are used.
First, a chamber or condenser is fitted up to act as follows:-A valve box
is placed beneath the exhaust pipe of the cylinder, and when the engine
exhausts it lifts this valve, thereby admitting a quantity of steam, which is con-
ducted from the clack box into the chamber or condenser which is placed.

page_text: Deneath the foot plate of the engine (or at any other convenient part of the
engine), with a cock to regulate the necessary quantity of steam required.
The steam so conducted into this chamber or condenser is to heat the water
prior to its being pumped into the boiler, and acts as follows:-The steam
passes through pipes from the valve box beneath the exhaust pipe of the
cylinder into the bottom of the chamber or condenser, which chamber has also
another valve placed on it to prevent the water from running down the pipe.
Half way up the condenser there is a plate bored with a multiplicity of water jet.
holes, so that when the water is turned on from the tender it rushes downwards
through these holes, and coming in contact with the exhaust steam admitted as
above described, condensation takes place, and the water becomes heated to a
great extent. To the bottom of the condenser the feed pipe of the pump is
attached, and of course this heated water is pumped into the boiler.
Second, in further economising fuel an apparatus is applied to serve two
purposes, namely, to prevent to a great extent all waste steam from blowing
into the atmosphere from the safety valves, and also to serve as a steam pres-
sure guage. If applied only to save the waste steam, a common valve will
suffice, but if intended to serve both purposes, there is applied a cylinder with
a solid piston, equal to any number of inches of area required, with a spring
above the piston to cause the necessary pressure upon the square inch, with a
4 or 6 inch range, which is divided into pounds. When the steam pressure
becomes greater than the working pressure fixed upon, the piston ascends and
the steam passes through an aperture in the cylinder, and is then conducted
into the tender, thereby saving or preventing the steam from being wasted, and
of course heating the water in the tender to a great extent.
And in order that my said Invention may be properly understood. I shall
now proceed to describe the several illustrative Figures on the explanatory
Sheet of Drawings, which I have hereunto appended, for the purpose of showing
certain modifications under which my improvements may be judiciously carried
out in practice.
My Invention relates, firstly, to the arrangement and construction of the fur-
naces of locomotive and other engines. By means of these improvements the
gases generated by the combustion of the fuel are retained within the furnace for
a much longer time than can be effected in furnaces of the ordinary kind. Thus.
by preventing the escape of the gaseous matters, and duly regulating the admis-
sion of atmospheric air with regard both to time and quantity, perfect combustion
is obtained, and a considerable saving of fuel is effected.
These improvements may be readily adapted to furnaces at present in use, or
applied in the construction of new furnaces.

page_text: Figure 1, on my Sheet of illustrative Drawings, is a longitudinal section of
a portion of a locomotive engine, showing the fire box of the engine, with one
modification of my improvements applied thereto. Figure 2 is a sectional eleva-
tion, corresponding to Figure 1.
Figure 3 is an end view of a locomotive boiler, showing one mode of admitting
air to the fire box.
Figure 4 is a longitudinal section of a fire box and portion of a locomotive
boiler, showing another modification of my improvements for retaining the
gaseous matters within the fire box.
Figure 5 is a longitudinal section of a fire box and part of a boiler, showing
another arrangement for promoting the effectual combustion of the gaseous mal-
ters evolved from the burning fuel; Figure 6 is a sectional elevation, correspond-
ing to Figure 5; and Figure 7 is an end view of the boiler to show the applica-
tion of the air chamber thereto.
In applying my improvements to locomotive engines having furnaces or fire
boxes of the ordinary kind, a bridge or midfeather, constructed of fire-clay
bricks or fire-clay slabs, is built across the fire box from side to side. This
bridge or midfeather A rises obliquely upwards from below the tubes of the
boiler, and extends towards the door of the fire box, as shown in the longitudinal
section, Figure 1 of my Sheet of Drawings. The bridge A may be built either
close up to the tube plate B, or a space may be left between the bridge and the
plate, as shown in Figure 1 of my Drawings.
In carrying out these improvements in locomotive engines, the fuel intended
to be used is coal instead of coke, which is at present used. The fuel as it is
put into the furnace is thrown towards the back part of the arched bridge A.
The gaseous matters as they are evolved cannot escape to the tubes by reason
of the bridge A intervening; they are consequently compelled to return
towards the front of the fire box. The gaseous matters are by this means
retained for double the length of time in the improved furnace compared with
what they would be in a furnace of the ordinary kind; it follows, therefore,
that the air which is admitted to the fire box, in order to promote the com-
bustion of the gaseous matters, produces a much greater effect in consequence
of the gases being confined as it were within the fire box. The air which
serves so important an end in promoting vivid combustion, and preventing the
emission of visible smoke, is admitted through a number of apertures or jet
holes C. For the admission of air to the back part of the fire box the jet
holes C are made through the outer shell of the boiler and the tube plate, and
are made below the bridge or midfeather A, as shown in Figures 1 and 2 of
my illustrative Drawings. A further supply of air is also admitted at the

page_text: front end of the fire box; these apertures or jet holes D are made through
the outer shell of the boiler and the fire box, as shown in Figure 3 of my Draw-
ings. The jet holes D are covered with a cast-iron box or air chamber E,
which surrounds the fire door, and the air passes into the air chamber through
an annular aperture made round the fire door. The flame plate of the fire door
is likewise pierced with a number of holes in order that the air may be distri-
buted in such a number of small jets or streams that no injurious effect may be
produced on the tubes, at the same time effecting the full combustion of the
gaseous matters, and preventing the emission of smoke.
In the modification of my improvements, shown in Figure 4 of my Sheet of
Drawings, the bridge or midfeather is made of copper, and forms a flattened
tube extending from side to side of the fire box. The bridge F is not fitted close
up to the tube plate G, but is fixed at some distance therefrom, and the inter-
vening space is made up of fire-clay slabs or fluc covers H. This
arrangement prevents the gases from escaping to the tubes before complete
combustion has been effected. The atmospheric air is admitted to the furnace
by means of the arrangement before described in reference to Figures 1 and 2 of
my Drawings.
In the modification of my improvements, shown in Figures 5, 6, and 7 of
my Sheet of Drawings, the bridge or midfeather 1, which serves to retain the
evolved gases within the furnace, is riveted to the crown and sides of the fire
box. In this arrangement the bridge I forms a flattened tube extending
across the fire box and up the sides towards the crown. The space between
the bridge and tube plate J is filled up with fire tiles K. The space filled in
with the fire tiles is of such a width, that when the tiles are removed there is
room enough for removing and replacing the tubes L. Or, the bridge I may
be carried close up to the tube plate and riveted thereto. In this modification
a man-hole is made in the bridge, so that the tubes may be got at when
required. The gaseous matters, as they are evolved from the burning fuel,
travel forwards towards the fire door; they then pass through the opening M
made for the purpose in the bridge, and into the chamber N where the complete
combustion is effected. In this modification the arrangement of the parts for
the admission of air is the same as before described, and marked with similar
letters of reference.
In carrying out my Invention as applied to locomotives when the engine is
standing still, a jet of steam is admitted to the chimney by means of a cock fitted
on the boiler. The steam causes a draught through the chimney, and the air is
thereby drawn through the several jet holes, so that the combustion of the gases
is kept up.

page_text: Figure 8 of the illustrative Drawings is a longitudinal elevation, partially in
section, of a locomotive boiler; Figure 9 is a half end elevation and vertical
section, corresponding to Figure 8. In these Figures is shown an arrange-
ment for shaking the fire bars of engines in order to prevent the formation of
clinkers, and avoid the necessity of clearing, or as it is technically termed,
"pricking" the fire bars. The arrangement consists of a transverse rocking
shaft O, which is fitted with a number of short arms or vertical levers P; the
upper ends of the levers P are forked, and the front end of each alternate fire
bar rests in the fork of the lever. Near to one end of the rocking shaft O is
attached a lever Q, to the free end of which is jointed the hand lever R; this
lever extends upwards, so as to be within convenient reach of the engine
driver. By simply lifting the lever R, the alternate bars are raised above the
adjoining bars, and thereby freed from clinkers, which operation may be
repeated as often as necessary. Figures 8 and 9, also show the application of
my several improvements to a locomotive boiler; these will be hereafter
referred to.
Figure 10 of my illustrative Drawings is a front view of an arrange-
ment of apparatus for economising fuel; Figure 11 is an end view of the
same. It consist of a condenser or chamber S, fitted underneath the foot
plate of the engine, or in any other convenient part. A valve box is fitted
below the exhaust pipe of the cylinder, and this valve box T, Figure 8, com-
municates by means of a steam pipe U with the interior of the condenser S;
an union pipe V serves to connect the condenser S with the cold water tank.
The water which flows into the condenser is pumped out through the two feed
pipes W; the interior of the condenser is divided longitudinally by a per-
foration partition or diaphragm X. When the engine exhausts, it lifts the
valve in the box T, and the steam rushes through the pipe U into the
condenser; the quantity of steam admitted is regulated by means of the cock
Y, Figure 8. When the water is turned on from the tender, it rushes
through the pipe V, and through the holes of the diaphragm X; the water
divided in this manner rapidly condenses, and its temperature becomes pro-
portionately raised. A valve is fitted on the end of the steam pipe U inside
the condenser, in order to prevent the water from flowing down the steam
pipe; the heated water is pumped through the pipes W into the boiler of the
engine.
Figure 12 is an elevation, and Figure 13 a vertical section, of an
apparatus for preventing, to a great extent, steam from blowing into the
atmosphere from the safety valve; the apparatus also serves as a steam
pressurge guage. If this apparatus is used only for the purpose of saving

page_text: steam, an ordinary valve fitted in the lateral branch pipe Z will be sufficient;
the steam from the safety valve flows through the main pipe and away by the
branch Z to the tender. But when the apparatus is intended to serve as
a pressure guage as well as a steam saver, a cylinder is applied thereto fitted
with a solid piston or plunger a, Figure 13, equal to any number of inches of
area required. Above the piston is a spring b to give the necessary pressure
upon the square inch, with a four or six inch range, divided into pounds.
When the steam pressure exceeds the predetermined working pressure. the
piston a ascends, and the steam passes through an aperture in the cylinder,
and is carried into the tender where it serves to raise the temperature of the
feed water. In Figure 8, the steam saver is shown fitted to the boiler, with
its branch pipe leading to the tender. The cock for controlling the admission
of the exhaust steam to the condenser is shown at d. In some cases it may
be necessary to convey a current of air into the air chambers, described in the
first part of this Specification; this is effected by means of a trumpet-
mouthed pipe, and leading into the air chamber above, or the air pipe may
be taken from the boiler down to the air chamber beneath, the trumpet
mouth being so arranged that it may be turned in any direction to catch the
wind.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I may observe in conclusion that I do not confine or restrict myself
to the precise details or arrangements which I have had occasion to describe or
refer to, as many variations may be made therefrom without deviating from the
principles or main features of my Invention; but what I consider to be novel
and original, and therefore claim as the Invention secured to me by the herein-
before in part recited Letters Patent, is,-
First, the general arrangement and construction of the furnaces of locomotive
steam engines, and the apparatus for economising the heat of the otherwise waste
steam, as herein-before described.
Second, the system or mode of retaining the gaseous matters evolved from the
burning fuel by means of solid and hollow bridges, or a combination of solid and
hollow bridges, as herein-before described.
Third, the system or mode of admitting streams or jets of atmospheric air to
promote the combustion of the gases retained within the fire box, as herein-
before described.
Fourth, the mechanical arrangement, by means of which the incandescent fuel
is prevented from adhering or clinking the fire bars.
Fifth, the system or mode of heating the feed water of the boiler by means

page_text: of the exhaust or used steam from the cylinder, and the mechanical arrangement
for effecting the application of the heat, as herein-before described.
Sixth, the system or mode of economising the steam blown off from the safety
valve by applying its heat to raise the temperature of the water in the tender,
and the mechanical arrangement for effecting the same, as herein-before described.
Seventh, the combination of the apparatus for economising the heat of the
waste steam with a pressure guage, as herein-before described.
In witness whereof, I, the said Thomas Yarrow, have hereunto set my hand
and seal, this Seventeenth day of September, One thousand eight hundred
and fifty-seven.
THOMAS YARROW
(L.S.)