CERTAIN IMPROVEMENTS IN LOCOMOTIVE STEAM ENGINES AND RAILWAY CARRIAGES
Year: 1869

page_text: LETTERS PATENT to Thomas Dunn, of Pendleton, near the City of
Manchester, in the County of Lancaster, Civil and Mechanical
Engineer, for the Invention of "CERTAIN IMPROVEMENTS IN LOCOMOTIVE
STEAM ENGINES AND RAILWAY CARRIAGES."
Sealed the 19th April 1870, and dated the 27th October 1869.
PROVISIONAL SPECIFICATION leit by the said Thomas Dunn at the
Office of the Commissioners of Patents, with his Petition, on the 27th
October 1869.
I, THOMAS DUNN, of Pendleton, near the City of Manchester, in the
County of Lancaster, Civil and Mechanical Engineer, do hereby declare
the nature of the said Invention for "CERTAIN IMPROVEMENTS IN LOCOMOTIVE
STEAM ENGINES AND RAILWAY CARRIAGES," to be as follows:-
My Invention consists in driving locomotive steam engines by means
of two or more central steam cylinders placed between the driving
wheels and in line with each other, the pistons of which are connected
direct to cranks on the shafts of the driving wheels; or I apply a
cylinder with two pistons, the piston rods of which pass through the
ends of the cylinder and are connected to cranks on the two driving

page_text: axles; or both the piston rods pass through the same end of the
cylinder and are connected to a double crank on the driving axle; or
1 apply one large and two smaller cylinders, the piston rods of which
are connected to a three-throw crank shaft with the cranks between the
driving wheels; or I apply two or more single or double cylinders
connected to cranks on the front and back driving or intermediate axles.
Two outside and one inside cylinders may be used, in which case the
driving axles are connected by a central link jointed to the connecting
rod; this centre link may be used in lieu of the ordinary outside links
for connecting the driving axles. This link can also be used when the
cylinders are in line with each other.
The boilers of my improved locomotive engines are made with a
shoulder near the fire-box, so that the tubular end is much lower than
the fire-box end, the object being to admit more tubes in the boiler and
to keep them immersed in the water; or two sets of tubes each in a
separate casing may be combined with a vertical boiler surrounding the
fire-box, which is divided into two parts by a water chamber.
The wheels of my improved locomotive engines are made of discs of
cast iron with a groove in the circumference, which groove is filled with
hard wood or other suitable material. The tyre is shrunk on the body
of the wheel, and is secured to it by pins or studs or by projections
rolled on the tyre These improved wheels may be used for railway
tenders, carriages, and trucks.
Another of my improved railway wheels consists of a disc of sheet
metal with angle iron rivetted on the circumference to form the felloe,
and with a cast steel or wrought-iron or other metal nave, from which
the journal projects so as to be easily repaired when worn. The axle is
made of a cast metal or wrought-iron tube, to the flanged ends of which
the wheels and naves are bolted or rivetted, or the body of the wheel
is made of two or more parallel pieces of wood crossing each other and
rolled to condense the wood. The nave, journal, and axle are made as
above described, or with a hollow cast-iron axle with the journals of
wrought iron or steel driven in, or the journals are made on an inner
axle passing through the hollow axle, so that in case one or both axles
were injured or broken the carriage would not fall to the ground; or
the axle and part of the wheel at each end are made of a wrought-
iron or cast metal tube with arms and flanges, to which flanged discs
are rivetted.
The journal is of cast steel or other metal rivetted to

page_text: the discs, and the tyre is shrunk on the flanges; or the body of the
wheel consists of two triangular frames rivetted together and to the
nave, the tyre being shrank on the angles of the frames, or on a hoop
fixed to them; or the body of the wheel consists of two discs of cast
iron with packing of wood between them, or two sets of corrugated or
bent arms or discs; each cast or forged with a portion of the nave may
be bolted together and secured to a tyre with a rib; or the wheel con-
sists of a cast-iron nave in two parts with broad spokes of wood or iron
segments between them.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Dunn in the Great Seal Patent Office on
the 26th April 1870.
'TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
DUNN, of Pendleton, near the City of Manchester, in the County of
Lancaster, Civil and Mechanical Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-seventh day of October, in the
year of our Lord One thousand eight hundred and sixty-nine, in the
thirty-third year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Thomas Dunn, Her special licence
that I, the said Thomas Dunn, my executors, administrators, and assigns,
or such others as I, the said Thomas Dunn, my 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 LOCOMOTIVE
STEAM ENGINES AND RAILWAY CARRIAGES," upon the condition (amongst
others) that I, the said Thomas Dunn, my executors or administrators,
by an instrument in writing under my, or their, or one of 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 I, the said Thomas Bunn, 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 (that is to say):-
The nature of my Invention consists,―
First. In certain improved arrangements of the cylinders of locomotive
steam engines whereby the power is applied in a direct line with the
rails.
Secondly. In an improved mode of connecting the driving axles of
locomotive engines.
Thirdly. In certain improvements in the boilers of locomotive
engines.
And, lastly. In certain improved modes of constructing the wheels of
locomotive steam engines and railway carriages.
And in order that my Invention may be fully understood and readily
carried into operation, I will proceed to describe the four accompanying
Sheets of Drawings.
On Sheet Figure 1 is an elevation partly in section, and Figure 2 a
plan of a locomotive steam engine constructed according to my improve-
ments. In these views the steam cylinders a and b are placed one
above the other in a centre line between the driving wheels, the piston
rod a from the cylinder a being connected by the connecting rod a³
to the crank of the front driving axle c, and the piston rod b' from the
cylinder by the connecting rod b to the crank of the hind driving
axle d. The cranks on the driving axles c and d are placed at or nearly
at right angles for assisting the cranks over the centres, and by apply-
ing the power to both cranks in a central line between the rails it is
evident that the tendency of the engine to oscillate is removed; whereas
in the ordinary mode of applying the power first on one side of the centre
of the crank shaft and then on the other the tendency of the strain is
constantly exerted in opposite directions, and the flanges of the driving
wheels are moved more or less towards the rails, thereby producing
oscillation. This improved position of the cylinders is particularly
beneficial when applied to locomotive steam engines for railways with
very narrow guages, but it is also advantageous for other locomotives
running at high speeds. The boiler which I prefer to use consists of
the fire-box e, with a water pocket or midfeather f, and with two firing-

page_text: doors g, the object of which is to reduce the quantity of air admitted
when the doors are opened for firing. The two sides of the fire-grate are
supplied with fuel alternately, so that when coal is used the smoke is to
a great extent consumed before the products of combustion enter the
tubes. The body of the boiler contains two sets of tubes marked h and
i, with a mixing chamber j between them; the fire-box e is made
higher than usual, and the steam dome is placed on the casing of the
fire-box, consequently the cylindrical part of the boiler is kept full of
water, and the tubes are entirely immersed. The cylinders a and b
are placed above and below the axle of the intermediate wheels, and
all the wheels are connected by the outside links m, as shewn in Figure 2.
Figures 3 and 4 represent in elevation and plan a modification of my
improvements in locomotive steam engines. In this instance a is the
steam cylinder placed within the smoke box, and b, b, are two other
smaller cylinders placed one at each side of the smoke box. The area of
the cylinder a must be twice as great as that of each of the cylinders b.
The cylinder a is connected by the piston rod a' and connecting rod a²
to a crank on the driving axle e, and the cylinders
are connected in
like manner to cranks on the ends of the axle c; by this arrangement
the propelling force is exerted in a direct line with the rails, as in
Figures 1 and 2, but half the force is exerted in a line with the centre
between the rails, and the other half at equal distances outside the rails,
thereby preserving the equilibrium and preventing oscillation. I wish
to observe that the cylinders b, b, may be placed at each side of the fire-
box instead of in the positions shewn.
On Sheet 2 Figures 5, 6, and 7 are an elevation, plan, and end view
of another modification of my improvements in locomotive steam engines.
In these views a is a steam cylinder placed below the level of the fire-
box, and b is another cylinder placed in the smoke box; both these
cylinders are in a line with the centre between the rails.
The piston
rod a from the cylinder a is connected by the rod a to a central crank
on the driving axle c, and the piston rod b' of the cylinder b is pro-
vided with a cross head connected by two rods be to two other cranks on
the driving axle c. The boiler is similar to that shewn and described
with reference to Figures 1 and 2, excepting a slight variation in the
shape of the midfeather or water chamber f in the fire-box e. I wish
to remark here that cylinders with two pistons similar to those patented
by John George Bodmer on the Twenty-fourth day of May One thousand

page_text: eight hundred and thirty-four, Number 6616, may be applied in like
manner for working the driving axles.
On Sheet 3 Figures 8 and 9 are a longitudinal and vertical section of
another of my improved steam boilers. In this case the fire-box e is
divided into two parts by a transverse midfeather or water chamber f.
The part e near the ends of the tubes h forms a mixing chamber, which
is supplied with atmospheric air or steam, or both air and steam, to
increase the combustion through perforations in the metal plate o and in
the fire-clay saddles n.
Figure 10 is an elevation partly in section, Figure 11 is an end view,
and Figure 12 a plan of another of my improved steam boilers. In this
instance the fire-box e and mixing chamber e' are similar to those
shewn in Figure S, but the air or steam is admitted through perforated
blocks forming the bottom of the chamber. There are two sets of
tubes, each contained in a separate elliptical casing q, which are.
stayed by cross belts, as shewn in Figure 11, but the casings may be
cylindrical if preferred. The tubes are all entirely immersed in the
water, and the steam generated by the tubes escapes into the steam
chamber at the top of the fire-box e, as in the boilers previously described.
Figure 13 represents a plan of a railway engine frame or truck shew-
ing the improved central connecting links m for coupling the three
axles, the link m shewn broken being connected to the next engine
frame. The links m are connected to cranks formed in or near the
centre of the driving axles, or a pair of Bodmer's cylinders patented the
Twenty-fourth day of May One thousand eight hundred and thirty-four,
Number 6616, may be applied outside the engine frame to work the
central crank; by this means the requisite adhesion on the rails can be
obtained on a very narrow guage line.
Figure 14 is a plan of a locomotive steam engine representing a
modification of this part of my Invention. The links m are dispensed
with, and on each side of the driving axle c is fixed a pulley 7, which by
means of straps or belts transmits motion to the front and back driving
axles on which other pulleys of the same diameters are fixed. Although
the crank is shewn on the centre axle it may be on either of the end
axles, or a pulley and strap, as shewn in dotted lines, may be used to
connect the power from the next carriage frame.
On Sheet 4 Figures 15 and 16 are a section and elevation of a pair of
my improved wheels and axles. The wheels consist of a strong cast or

page_text: wrought iron plate
iron axle t. The tyres are made of cast iron cast under heavy pressure
to condense the metal, or by preference of steel or homogeneous metal,
the internal flange of the tyre fitting on a rib projecting from the plates,
or the plate may be curved to reduce the projection of the axle, as shewn
in Figure 17. The tyres are rivetted or bolted to the plates s, and can
easily be replaced by others when worn or injured. When the hollow
axle is of wrought iron the ends are partially closed by bushes, which
are bored out to receive the ends of the journals w, which are keyed to
the axle, and are made with flanges, which are rivetted or bolted through
the plates and through the flanges on the hollow axle. These journals
can also be easily replaced when worn or injured.
bolted to a flange on the hollow cast or wrought
Figures 17 and 18 represent a section and end view of another of my
improved wheels and axles. The wrought iron, homogeneous metal, or
steel axle is cut into eight or other convenient number of divisions at
cach end, these divisions are bent at right angles to the axle to form
parts of the spokes, and the outer end of each portion of a spoke is also
bent and curved at the top to form part of the felloe of the wheel; the
other portion of the felloe and spokes and the nave of the wheel are
made of the wrought iron, homogeneous metal, or steel plates, to
which the flange of the journal is bolted or rivetted. The tyre u is
roiled with a central rib, which when the tyre is shrunk on fits in the
space between the tops of the spokes, or the rib may be placed in its
position without shrinking.
Figures 19 and 20 represent a section and end view of another of my
improved wheels, the axle being of the ordinary description. Each
wheel consists of two half sets of spokes, with their ends bent to receive
the tyre u, the spokes being cast or welded to the half naves. These
two halves of the spokes are curved to give them the required elasticity,
and they are bolted or rivetted together at intervals. The tyre u may
be made with a deeper internal rib than that shewn in reference to
Figure 17 if required.
Figures 21 and 22 are a section and end view of another of my
improved wheels. The axle is made as usual. The wheel consists of
a cast-iron nave a, with a flange and a circular rim on which the wood
segments y rest. These segments are held by bolts or rivets between
the flanges of the nave and the metal ring z, which fits on the boss of
the nave.
The segments y are secured to the nave by flat radiating

page_text: bolts, which answer also as tongues or tenons for the joints of the wood,
and the tyre u is rolled with a deep flange on one side, which is bolted
or rivetted to the segments y, the bolts or rivets passing also through an
annular ring on the inside of the wheel. In order to facilitate the
rolling of the tyre with a deep flange I first partially roll the tyre, as
shewn in Figure 23, then bore holes at.intervals through the flange, and
cut slots from each hole to the inner circumference of the flange. The
operation of rolling is then repeated, which causes each of the slots to
expand, leaving the inside of the flange with vandyked projections, as
shewn in Figure 24. When the tyres are made of cast steel or homo-
geneous metal the holes and slots are cast in before rolling, or in place
of the deep flange on the tyre u, the tyre and flange may be made in
separate pieces, as shewn in the enlarged sections Figures 25, 26, 27,
28, 29, & 30. In these cases the parts which are liable to wear, out
soonest can easily be replaced; or they may be made of tougher or denser
metal than those parts which are not exposed to so much wear and tear.
Figures 31 and 32 are a section and an end view of another of my
improved wheels and axle. The axle is of cast iron in two parts,
bolted together near one end, the flanges for the coupling forming also
a drum or pulley, on which a break may be applied. The journals w
are separate from and connected to the axle, as shewn in Figure 15,
and the body of the wheel consists of three or other suitable number of
planks of wood let into each other at the nave, and through which the
inner end of the journal w passes. Wedge-shaped knee pieces of metal
are bolted or screwed between the wood planks. The tyre u is similar
to that shewn in Figure 21. In order to condense the wood for making
the above or other wheels I cause it to pass between rollers, as shewn
in Figure 33 on Sheet 3, and in order to prepare the wood I submit it
to the action of steam under pressure, either with or without preserving
fluid.
Figures 34 and 35 represent a section and an end view of another of
my improved wheels and axles. In this instance the inner axle tis
made as usual, but it is surrounded by a hollow axle ', so that in case
one or both axles are injured or broken (unless the fractures should
exactly correspond) the carriage would not fall to the ground. The
space between the axles is filled with charcoal and glue or other suitable
non-conductor. The nave of the wheel is keyed on the solid axle, and
the body of the wheel is made of alternate parallel and wedge-shaped

page_text: pieces of wood bolted or rivetted between the flange of the hollow axle
and the flange of the nave. The tyre u is similar to that shewn in
Figure 21, and secured to the body of the wheel in the same manner.
Figure 36 represents a front view of another of my improved wheels.
In this instance the body of the wheel consists of two triangular frames
of angle iron rivetted together and to the nave plate, the tyre being
shrunk on the corners of the frames or on a hoop fixed to them.
On Sheet 3 Figures 37 and 38 are a section and side view of another
of my improved wheels. In these views the wheel consists of a solid
cast-iron disc, with a boss keyed on the axle, and with a groove in the
circumference, which groove is filled with hard wood or other suitable
material. The tyre u is shrunk on the body of the wheel, and secured
to it by pins or studs. The interior of the tyre is slightly recessed, and
the disc of the wheel is cast with radiating slots to allow for the con-
traction of the metal when cooling; or this wheel may be cast without
the groove in the circumference.
On Sheet 2 Figure 39 is a section of another of my improved wheels.
In this case each wheel consists of two solid discs keyed on the axle and
bolted or rivetted together, the outer circle of bolts passing also through
the inner rim of the tyre u. A packing of wood or canvas, pasteboard,
or other suitable substance may be placed between the two discs to
prevent vibration and noise. The wheels shewn in Figures 37, 38,
and 39 are particularly adapted for locomotive steam engines, as owing
to the great weight of the wheels adhesion on the rails is obtained with-
out increasing the weight on the journals. These heavy wheels also
act. on the locomotive in the same manner as the fly wheel on a stationary
steam engine.
Having thus stated the nature of my Invention, and described several
modes of performing the same, I declare that I claim,―
First. The application of the power to locomotive steam engines in a
direct line with the rails, whereby the tendency to produce oscillation is
entirely removed, as described and partly shewn in the Drawings.
Secondly. Connecting the driving and other axles of locomotive
engines and carriages by means of central links and cranks, or by pulleys
and straps, as described and partly shewn.
Thirdly. The various improvements in the construction and arrange-
ment of parts of steam boilers, and particularly the application of the

page_text: THOMAS DUNN. (L.S.)
THOMAS DUNN. (L.S.)