IMPROVEMENTS IN STEAM TRAMWAY LOCOMOTIVES, AND IN THE MACHINERY AND APPARATUS CONNECTED THEREWITH
Year: 1876

page_text: LETTERS PATENT to Henry Percy Holt, of Royal Insurance Buildings, Leeds,
in the County of York, Civil Engineer, for the Invention of "IMPROVEMENTS
IN STEAM TRAMWAY LOCOMOTIVES, AND IN THE MACHINERY AND APPARATUS
CONNECTED THEREWITH."
Sealed the 18th May. 1877, in pursuance of an Order of the Lord Chancellor, and
dated the 8th November 1876
PROVISIONAL SPECIFICATION left by the said Henry Percy Holt at the
Office of the Commissioners of Patents on the 8th November 1876.
HENRY PERCY HOLT, of Royal Insurance. Buildings, Leeds, in the County of
York, Civil Engineer. "IMPROVEMENTS IN STEAM TRAMWAY. LOCOMOTIVES, AND
IN THE MACHINERY AND APPARATUS CONNECTED THEREWITH."
The object of this Invention is to provide a steam tramway locomotive in which
the boiler working pressure is maintained. nearly constant, and the exhaust.
steam. rendered noiseless and invisible by means of self-acting apparatus, and fuel
and water only require feeding at the termini; thus the driver's attention can be
entirely given to stopping and starting his engines.
The first part of this Invention consists in making the fire-box of larger dimen-
sions than is requisite for raising the steam required, and providing an escape flue:
to carry off the superfluous heat to the chimney without passing through the boiler
tubes. The escape of superfluous heat is controlled by a damper, which is worked
through the medium of a loaded piston or diaphragm by any variation of the
working pressure in the boiler; consequently if steam rises the damper is opened,
and less heat, passes through the boiler tubes on account of its being able to escape
to the chimney; on the other hand, if steam falls the damper is closed, and the
whole leat from the fire is passed through the boiler tubes to increase steaming
capacity. The superfluous gases are utilized for absorbing the exhaust steam and
rendering it invisible.
The second part of this Invention consists in making the receiver into which the
engines exhaust under a back pressure a surface condenser; the, exhaust steam is
then passed through an annular jet blower having a series of annular nozzles,;
between which inward currents of air are induced from the atmosphere by and
D 1:71
:

page_text: The air
brought in contact with the exhaust steam. This current is passed through a
separating chamber to arrest the water condensed by the air, and then carried
through or around the surface condenser, where it is heated, and thus ren-
dered capable of carrying off invisibly a larger amount of vapour.
after passing through the condenser may be taken either into a closed ash-pan to
blow the boiler fire or used to increase the chimney draught by passing through
induction nozzles in the smoke box or chimney. In some cases I blow both under
the flue and into the chimney, and regulate the amount of air admitted to either
by the variation of pressure of the steam in the boiler; water lodges are formed to
collect the condensed water, both in the surface condenser and between the blower
and the condenser, from which the water may be pumped back into the boiler.
The condensing surface may be of any suitable form.
In the third part of this Invention the velocity of the current of air for con-
densing and superheating the exhaust steam before passing into the chimney to
induce the draught is increased by a jet of live steam. This may be accomplished
by passing the mixture of air and steam after leaving the condensing heaters, as
described in the second part of this Invention, through a secondary or "revivifying"
jet blower worked by steam from the, boiler, by which its velocity and quantity is
increased; it is then passed through a series of annular nozzles connected with the
smoke box or chimney for the purpose of inducing draught and mixing the exhaust
steam with the hot gases from the boiler fire for absorbtion.
The fourth part of this Invention consists in making the blower with a self-re-
gulating back pressure exhaust steam nozzle as follows:-The steam nozzle is annular,
having an air opening in the centre through which air is drawn from the atmosphere
by induction, and so arranged that the central conical ring can slide back under the
control of an adjustable spring, and thus increases the area of the annular opening by
any increase in the exhaust steam pressure; on the contrary, should the steam pressure
fall less resistance is offered to the spring, and the annular opening is reduced in
area by this means. The back pressure in the exhaust receiver or condenser is
maintained nearly constant to that pressure for which the spring is adjusted; and
when the engines are stopped the back pressure is partially maintained, so that
when they are started again the current of air in the jet blower from the exhaust
pressure is quickly re-established.
In some cases in connection with the above I introduce a spray of water to
further assist in condensing the steam and cooling the condensing surface. An
exhaust steam feed water heater may be likewise used to further assist in con-
densing the steam, and at the same time heating the water.
In some cases I do not blow into the ash-pan at all, but use one or more annular
jet blowers with a large number of nozzles, and condense a large portion of the
exhaust steam by contact with the air induced; the air and partially condensed
steam are then passed through a separating chamber in which-the direction of the
current changed several times, and the condensed water thus thrown down and
pumped back into the boiler; the air current is then utilized to produce the
chimney draught by escaping through annular nozzles in the smoke box or chimney.
The fifth part of this Invention consists in placing the chimney of a horizontal
boiler centrally on the engine, and bringing the waste products from the smoke
box back to the chimney. Around the chimney bars several annular nozzles are
arranged through which air heated by passing through jackets round the smoke box
boiler and flues is induced into the chimney, which is made of large size by the air
nozzles before named. The heated air is introduced for the purpose of absorbing
the exhaust steam, and it partially saturated by it, and thus carried off invisibly.
The safety valves, regulator, and other fittings may also be arranged under the jacket
to be out of sight.
In some cases, more especially under ground, instead of carrying the chimney
upwards, I carry it down through a plate extending under the engines, and allow
the products of combustion to escape along the ground..
.
The engines are compound principle; and the sixth part of this Invention pro-

page_text: vides an improved arrangement for admitting high-pressure steam to the low-
pressure cylinder for starting, or when extra power is required, and at the same
time provides for the exhaust of the high-pressure cylinders. This consists in
placing a back-pressure valve between the low-pressure steam chest and the mid-
exhaust receiver, and providing an extra port in the regulator connected with the
low-pressure steam chest in such a manner that when the regulator is full open
steam is admitted to the low-pressure chest, but cannot enter the mid-exhaust
receiver. The mid-exhaust receiver is likewise provided with a similar back-
pressure or escape valve, so arranged that the high-pressure exhaust can be allowed
to pass by the mid-exhaust receiver, and exhaust into the low-pressure receiver, as
in a simple engine, without emptying the mid-exhaust receiver.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Percy Holt in the Great Seal Patent Office on the 21st
May 1877.
HENRY PERCY. HOLT, of Royal Insurance Buildings, Leeds, in the County of
York, Civil Engineer. "IMPROVEMENTS IN STEAM TRAMWAY LOCOMOTIVES, AND
IN THE MACHINERY AND APPARATUS CONNECTED THEREWITH."
The object of this Invention is to provide a steam tramway locomotive in which
the boiler working pressure is maintained nearly constant, and the exhaust steam
rendered almost noiseless and invisible by means of self-acting apparatus. Fuel and
water only require feeding at the termini; thus the driver's attention can be entirely
devoted to keep a sharp look out, and to start and stop the engine.
The first part of this Invention consists in making the fire-box and grate of larger
dimensions than are requisite for raising the average amount of steam consumed by
the engine, and in providing an escape flue to carry off the superfluous heat, either
to a secondary chimney; as shewn in Figures 1, 3, 5, and 6, having its own blast
pipe which may be fixed either above or below the damper, or carried by means of
a flue carried into one chimney; I prefer however to use two chimneys, each having
independent blast nozzles with several cones to mix as large an amount of hot air
with the exhaust steam as possible. The escape of superfluous heat to the chimney
without passing thro' the boiler tubes is controlled by a damper, worked by a
loaded piston by means of the boiler pressure, any variation in which moves the
damper either closer to if pressure falls, or wider open if pressure rises. Con-
sequently, if steam rises the damper is opened wider, and less heat passes through
the boiler tubes on account of its being able to escape thro' the secondary chimney;
on the other hand, if steam falls, the damper closes and more heat from the fire
passes through the boiler tubes to increase steaming capacity.
This
In some cases I prefer to use a plain cylindrical boiler with tubes thro' it, and to make
the fire-box of fire-brick or any other suitable material, without a water space round-
it, as shewn in Figures 2 and 4, and use the surface of the fire-box to superheat the
exhaust steam by passing it round the same on its way to the blast nozzles.
form of fire-box may be used for either horizontal or vertical boilers, and the damper
may be of the forms shewn in either Figures 1 or 2; in the latter more of the radiated
heat is cut off from the boiler. The superfluous gases are used for absorbing the
exhaust steam and rendering it invisible.
The second part of this Invention is shewn in Figures 2, 3, 4, and 6, and consists
in making the receiver (into which the engines exhaust under a back pressure) a
surface condenser; the exhaust steam is then passed through an annular jet blower
having a series of annular nozzles, between which inward currents of air are in-
duced from the atmosphere by and brought in contact with the exhaust steam.
This current is passed through a separating chamber to arrest the water condensed

page_text: by the air, and then carried through or around the surface condenser, where it is
heated, and thus rendered capable of carrying off invisibly a larger amount of
vapour. The air after passing through the condenser may be taken either into a
closed ash pan to blow the boiler fire, or used to increase the chimney draught by
passing through induction nozzles in the smoke box or chimney. In some cases I
blow both under the fire and into the chimney, and regulate the amount of air
admitted to either by the variation of pressure of the steam in the boiler as before
described for the damper. Water lodges are formed to collect the condensed water
both in the surface condenser and between the blower and the condenser, from
which the water may be pumped back into the boiler. The condensing surface may
be of any suitable form.
In some cases in connection with the above I introduce a spray of water into the
induction nozzles to further assist in condensing the steam and cooling the con-
densing surface, which water is caught in the ledges; an exhaust steam-feed water
heater, formed of a coil of pipe fixed in the receiver, may likewise be used to further
assist in condensing the steam.
In order to mix the exhaust steam more thoroughly with the heated gases I use a
series of conical nozzles in the smoke box, and supply the exhaust steam from the
receiver in two or more places in the series of nozzles through jets or annular
'nozzles, as shewn in Fig. 2; by this means the induced current through the several
rows of tubes is of more uniform velocity, and less dust is drawn from the fire.
In the third part of this Invention the velocity of the current of air for con-
densing and superheating the exhaust steam (before passing into the chimney to
induce the draught) is increased by a jet of live steam; this may be accomplished
by passing the mixture of air and steam after leaving the condensing heater (as de-
scribed in the second part of this Invention) through a secondary or "revivifying" jet
blower (worked by steam from the boiler), by which its velocity and quantity is in-
creased; it is then passed through a series of annular nozzles connected with the smoke
box or chimney for the purpose of inducing draught and mixing the exhaust stram
with the hot gases from the boiler fire for absorbsion.
The fourth part of this Invention consists in making the blower with a self-
regulating back pressure exhaust steam nozzle, as follows:-The steam nozzle is
annular (having an air opening in the centre, through which air is drawn from the
atmosphere by induction) and so arranged that the central conical ring can slide
back under the control of an adjustable spring, and thus increase the area of the
annular opening by any increase in the exhaust steam pressure; on the contrary,
should the steam pressure fall, less resistance is offered to the spring, and the
annular opening is reduced in area; by this means the back pressure in the exhaust
receiver or condenser is maintained nearly constant to that pressure for which the
spring is adjusted, and when the engines are stopped the back pressure is partially
maintained, so that when they are started again the current of air in the jet
blower from the exhaust pressure is quickly re-established.
In order to avoid any steam from the safety valve blowing off frequently, and at
the same time diminish the quantity to blow off, should it occur, I use a nozzle
blower with a self-regulating steam nozzle, as above described in the fourth part of
this Invention, to force air through tubes, or by preference coils or worms fixed inside
the boiler; the air becomes dried and heated and absorbes the steam in passing thro' by
means of heat taken from the boiler, the pressure in which is consequently reduced.
The self-regulating jet is loaded to open at a lower pressure than the safety valves,
which are simply used as a safeguard. The current from the boiler coils may be
taken to blow down the chimney or chimnies and check the draught, or be turned
under the engine.
In some cases I not blow into the ash pan at all, but use one or more annular jet
blowers with a large number of nozzles, and condense a large portion of the exhaust
steam by contact with the air induced; the air and partially condensed steam are
then passed through a separating chamber in which the direction of the current is
changed several times, and the condensed water. thus thrown down and pumped

page_text: back into the boiler; the air current is then utilised to produce the chimney draught.
by escaping through annular nozzles in the smoke box or chimney.
The fifth part of this Invention consists in placing the chimney of a horizontal.
boiler centrally on the engine, and bringing the waste products from the smoke.
box back to the chimney. Around the chimney base several annular nozzles are
arranged through which air (heated by passing thro' jackets round the smoke box,'
boiler, and flues) is induced into the chimney (which is made of large size) by the air
nozzles before named. The heated air is introduced for the purpose of absorbing>
the exhaust steam, and is partially saturated by it, and thus carried off invisibly..
The safety valves, regulator and other fittings may also be arranged under this.
jacket to be out of sight.
In some cases (more especially under ground) instead of carrying the chimney:
upwards, I carry it down diagonally through a plate extending under the
engines and allow the products of combustion to escape along the ground, and for
mines I construct the fire-box with an inclined grate, the higher end being. towards
the down-cast shaft, the smoke box having no bottom and inclined, as shewn in
Figure 8.
The sixth part of this Invention consists in an improved arrangement for ad-
mitting high-pressure steam to the low-pressure cylinder when compound engines
are used, and in providing a free exhaust of the high-pressure cylinder without
exhausting the mid-exhaust receiver, which I place inside the boiler to avoid loss.
by radiation. This I do in two ways.
Firstly. Without coupled connections, by means of a secondary port in the steam
regulator connected with the low-pressure steam chest which does not open until
the high-pressure port is wide open between the low-pressure steam chest and the
mid-exhaust receiver. . I fix a back pressure valve which closes automatically when
the pressures in each are exactly equal, or that in the low-pressure chest is in excess,
as when steam is admitted from the boiler to the low-pressure steam chest. I lead
a pipe into a cylinder containing a piston open at the opposite side of the piston to.
the mid-exhaust receiver; this piston is connected to a valve which closes the con-
nection from the high-pressure cylinder to the mid-exhaust receiver, and at the
same time opens the high-pressure exhaust to the atmosphere or condenser whenever
the pressure in the low-pressure steam chest exceeds that in the mid-exhaust:
receiver. This arrangement is shown in Figures 2 and 4.
Secondly. By means of coupled connections, in which I use two separate steam
regulators, one for the high-pressure cylinder, the other for the low-pressure cylinder,
by the arrangement of ports and valves, as shown in Figures 5 and 6; the con-
nections of passage are changed to admit either high or low-pressure steam to the
low-pressure cylinder, and provide an exhaust for the high-pressure cylinder without
much back pressure, and also without exhausting the mid-exhaust receiver.
The high and low-pressure valve motions are worked by separate levers and
weigh-bar-shafts, or in some cases by one shaft having a sleeve working on it in lieu
of a second shaft.
The high-pressure reversing lever has a catch which engages in a sector secured.
to the low-pressure lever with pallets which abut against stops whenever the low-
pressure lever is put over into full gear in either direction, and these stops disengage
the catch and allow the high-pressure lever to fall into full gear.
Sometimes I use a screw in place of a lever. This arrangement is shown in.
Figures 7, 8, and 9. In order to enable the driver to see all round him I form the
water tank for feed or condensing water into the roof of the engine cab, as shown
in Figures 3 and 5, and where condensing surface is desirable I.fix tubes in the
tank, as shown in same Figures, in the roof.
Having now described the manner in which my Invention may be carried out, in
order to more fully explain the same I append. Drawings in which the letters of
reference are as follows,-
Figures 1, 3, 5, and 6-a, fire-box; b, escape flue; c, damper; d, d, cylinder. and
piston loaded by means of spring and connected with the boiler; e, e, connecting.

page_text: levers and balance weight; f, secondary chimney; g, g, ordinary chimney and
louvres for drawing in air; h, h, annular nozzle blast pipe; h³, h¹, blast pipe for
secondary chimney; i, low-pressure cylinder; k, k, k, k, intermediate or mid-exhaust
receiver fixed inside boiler to avoid loss by radiation; l, l, link motion and reversing
shafts;
,, reversing levers; m, m, m, high-pressure cylinder, steam regulator, and
connections; n, low-pressure cylinder, steam regulator, and connection to lever;
o, space connected with boiler; p, port to steam chest; q, exhaust port from
cylinder; r, port to mid-exhaust receiver; 8, port to absorbing apparatus and
atmosphere; s¹, pipe to absorbing apparatus and atmosphere from low-pressure
cylinder; t, space connected with boiler; u, port from mid-exhaust receiver; v, port
to low-pressure steam chest; w, exhaust receiver; x, condenser and superheater;
y, y, annular jet blowers; y¹, self-adjusting exhaust pressure nozzle; y², spring
regulated to give constant back pressure; z, z, water trap and connections to nozzles
in chimney or closed ash-pan; z¹, water tank made for convenience to form the roof
of cab; 2, surface condenser arranged in part of same to assist condensation of
exhaust steam.
Figures 2 and 4.-a, fire-box without water space and lined with any suitable
material; b, boiler and tubes; c, c, damper worked by self-acting apparatus, as in
Figure 1; e, e, escape flue; f, secondary chimney; 9, g, secondary blast pipe which
may have any convenient number of nozzles; h, primary chimney: i, annular jet
blast pipe having exhaust steam nozzles at and ;, mid-exhaust or intermediate
receiver; 7, back pressure valve; m, m, m, m, pipe from low-pressure steam chest,
piston, and valve for admission from high-pressure cylinder to mid-exhaust receiver;
n, fslide valve to exhaust high-pressure cylinder to the atmosphere; o, o, low-
pressure exhaust receiver and pipe; p, p, surface condenser and superheater; 9, 9,
condensed water lodges; r, connections to chimney blast jets, and in some cases
with the ash-pan which must then be closed to blow the fire; 8, 8, annular jet
blowers which circulate air and steam round the surface condenser and super-
heater P. P
Figures 7, 8, and 9 represent a locomotive suitable for tramways under ground,
in which the fire-box end must always be kept towards the downcast shaft. a, a,
fire-box with inclined grate to admit air from the ventilating current; b, b, inclined
smoke box bottom to allow exit of waste gases from fire; c, c, c, c, c, reversing shaft,
lever, and screw for low-pressure cylinder; d, d, d, reversing lever and sector for
high-pressure cylinder; e, e, e, independent rod and handle to notch up high-pressure
valve gear; ff, fork to drop high-pressure valve gear into full throw whenever the
low-pressure gear is placed in full gear either forwards or backwards. This arrange-
ment of reversing levers is also applicable to other compound tramway and loco-
motive engines.
Having now fully described and illustrated some of the manners in which my
Invention can or may be carried into effect, I wish it to be clearly understood that
I do not confine myself to the exact details of the same, as these may be varied in
many ways without deviating from the main features of my said Invention, but.
what I consider novel, and therefore claim as the Invention secured to me by the
herein-before in part recited Letters Patent is,―
First. The use of a secondary flue and chimney combined with a damper regu-
lated by the pressure of steam in the boiler, for the purposes named, substantially
as described and illustrated.
Second. The combination of parts for condensing and absorbing steam in tramway
locomotives, substantially as described and illustrated.
Third. The combination of parts and nozzles for inducing draught in tramway
locomotives, substantially as described and illustrated.
Fourth. The arrangement of self-adjusting exhaust steam blower for maintaining
constant back pressure and velocity of current for tramway locomotives, substantially
as described and illustrated.
Fifth. The arrangement for preventing steam from blowing off from the boiler
safety valves in tramway locomotives, substantially as described.

page_text: Sixth. The combined arrangements for admitting high or low pressure steam to
the low-pressure cylinder, and exhausting from high-pressure cylinder for the
purposes substantially as described and illustrated.
Seventh. The reversing lever arrangement for compound tram engines, sub-
stantially as described and illustrated.
Eighth. The arrangement of water tank or condenser to form the roof on
tramway locomotives, substantially as described and illustrated.
Ninth. The combined arrangement of fire and smoke box bottoms for underground
tram engines, substantially as described and illustrated.
Tenth. The combined or separate use of the above-named parts and apparatus on
one engine.
Eleventh. The use of the above-named apparatus and combination of parts on
steam tramway locomotives, either worked by automatic apparatus or by hand,
ubstantially as described and illustrated.
In witness whereof, I, the Henry Percy Holt, have hereunto set my hand and
seal, this Seventeenth day of May, in the year of our Lord One thousand
eight hundred and seventy-seven.
HENRY PERCY HOLT. (L.S.)