IMPROVEMENTS IN APPARATUS OR MEANS FOR SUPPLYING FURNACES WITH FUEL, AND IN FURNACE FLUES
Year: 1877

page_text: LETTERS PATENT to Joseph John Butcher, of Gateshead, in the County of
Durham, Engineer, for the Invention of “IMPROVEMENTS IN APPARATUS OR
MEANS FOR SUPPLYING FURNACES WITH FUEL, AND IN FURNACE FLUES."
Sealed the 19th February 1878, and dated the 26th September 1877.
PROVISIONAL SPECIFICATION left by the said Joseph Johu Butcher at the
Office of the Commissioners of Patents on the 26th September 1877.
JOSEPH JOHN BUTCHER, of Gateshead, in the County of Durham, Engineer.
"IMPROVEMENTS IN APPARATUS OR MEANS FOR SUPPLYING FURNACES WITH FUEL,
AND IN FURNACE FLUES."
My present improvements have reference to apparatus, commonly called mechanical
stokers, for supplying fuel to furnaces; also to means of preventing coal dust being
carried by the draught out of the chimney or stack of furnaces.
According to my Invention I construct mechanical stokers with the driving shaft
below the machine driven in any convenient way, above which is a box containing
two fans rotating as usual in a horizontal plane; these fans being supported entirely
from below, each upon a spindle which rests upon a collar supported within a ver-
tical bearing secured to the bottom of the fan box. This spindle, together with
the fan, is driven by a spur wheel placed upon the driving shaft through a pinion.
securely fixed upon the bottom end of the spindle.
I also sometimes use friction wheels and discs in place of the bevel gear, in which
case the collar upon the fan spindle is done away with, the weight of the fan and
spindle being supported upon the friction disc, which is secured to the bottom of
the spindle, as shewn in the Drawing attached to the Specification of Letters Patent
granted to me on the 11th day of April 1874, No. 1257.
I sometimes find it convenient to use a gear combining the advantages of both
those named. The edge of the pinion is so extended as to form a friction dise, and the

page_text: edge of the web of the bevel wheel is broadened and faced in a lathe, so as to act
against the under side of the lip upon the pinion just described. In this form of
gear the collar upon the fan spindle is also done away with, the weight of the fan
and spindle being supported, as in the case of the friction gear, through the friction
lip upon the pinion upon the friction edge of the wheel.
The peculiar advantage of this form of gear is that, while it possesses all the
certainty of action of ordinary bevel gear, it is yet almost as noiseless as friction
gear, as the teeth of the wheel and pinion never come in working contact, except
when the friction between the edge and lip are insufficient to drive the fan alone,
and even in this latter case the jar is much softened by the resistance to movement
between the friction surfaces.
The attachment of the fan to the spindle may be effected in one of two ways,
both of which have been found to give the necessary rigidity.
Either the top of the fan may be driven tightly down over the enlarged top of
the spindle upon a collar, and secured in its position by a nut upon the spindle
end, or it may be drawn down upon a cone upon the end of the spindle by means
of a nut upon the spindle end, as before.
In either case the spindle end is enlarged and bored out, so as to form a tallow
cup, from the bottom of which a channel conducts the lubricant to an annular greaso
reservoir in the spindle guide.
Upon the centre of the shaft, midway between the bevel wheels, is turned an
eccentric driving an eccentric strap, the wear in which is easily taken up by means
of a loose block and set pin. A rod is secured into this strap, at the other end of
which is formed a gab-and-ball weight. This gab rides upon two pins turned upon
the bottom ends of levers which swing upon a centre pin, and through them drives
the ram or plunger to which the levers are attached. The centre pin, forming the
fulcrum upon which the levers swing, is free to turn within the loose block, which
can be moved up or down a slot in a bracket at pleasure. The ends of this pin
are squared, and free to move up and down through slots in the levers, and at each
end of the pin beyond the square is fixed a small handle to enable the man in
charge to raise or lower the centre pin. From the bottom of the block hangs a pin
which passes through a hole drilled in the bottom of the bracket, and serves to
enable the man in charge by means of the set pin to clamp the block fast in any
required position. This movable centre to the lovers enables them to be adjusted
to any required length of stroke, the ram having a small traverse when the pin is
at the top of the slots, and a large traverse when it is at the bottom, the amount
of coal fed by the ram through the aperture on to the fans being correspondingly
less or greater.
I sometimes find it convenient to make the feed adjustable by means of a screw
so placed as to raise or lower the block and centre pin on which the levers swing.
In this case I prefer to arrange the screw within the slot in the central fixed bracket,
cutting a corresponding thread within the block through which it passes, and slotting
out the pin in such a manner as to allow these parts to pass freely over one another
without contact. This centre pin has squared ends as before, but the handles
beyond them are unnecessary. The excentric rod gives motion to the levers by an
eye through a pin and other eyes. The top ends of the levers give motion to the
rain through pins which are made in a piece with them, and project into and are
free to turn within the eyes, which are attached or in a piece with the ram.
I may sometimes make the block solid with a pin projecting from it on each side
into and free to revolve within a small bearing with flat sides sliding within the
levers. The special advantages of these screw-adjusted levers are extreme ease of
handling and great variety of feed caused by the long slots they admit of, and by
their means when required a fire may be thoroughly "damped" or "banked down"
in a few minutes without any coal having been put on by hand. When the centre
pin is at the top of the slot the stroke of the ram is so short as to be practically
ineffective; but, in case of any inconvenience being caused by this small traverse
of ram, I sometimes slightly open the slots at the tops of the levers in such a

page_text: manner as to allow of the ends of the pin playing freely within it without coming
into contact with the sides of the slot, and in this way leave the ram entirely
without motion. This allows me to replace the gab in the eccentric rod with an
eyo which not only wears longer, but admits of the slots being so lengthened
downwards as to give the long traverse of the ram before mentioned.
The cover of the fan box is cast in a separate piece, and fitted on to its place;
and upon it a suitable recess or pocket is formed for the reception of the ram, and
the coal immediately contiguous to it. At the side of this pocket, which is opposite
to the ram, is formed a channel through which the coal is forced by the ram in the
direction of the edge over which its falls on to the fans, which project it in the usual
way on to the fire.
The channel I sometimes make separate from the main casting of the box cover,
and so arrange it that it is free to slide along a line cutting the two fan centres, so
as to enable me to adjust the amount falling upon each fan, and throw the coal
upon either side of the furnace or centrally, as required. To effect this purpose,
I either use a hand screw or lever, or other suitable gear attached to the side of the
sliding channel, so that it may be set to any desired position at will.
The tops of the fans pass up through holes cast in the box cover, which are larger
in diameter than themselves, a practically air-tight joint being formed by means of
a loose ring, which has a sharp edge on the inside, and fits closely, but not tightly,
around the fan top. Within this ring the fan turns freely, while the former lies at
rest upon the fan box top. This arrangement allows of a little inaccuracy in fitting,
and thus much reduces the cost of manufacture.
This machine, as above described, is complete in itself, and may be driven in any
convenient way from the end of the fan driving shaft. Where the flues, to
which they are affixed, are very exactly in line with one another, as in the furnaces
of a marine boiler, with two or four flues it is customary to couple the shafts
driving them directly from one end, or some other convenient point from the crank
shaft of an engine. As, however, where a line of boilers is fed by these machines
it is often necessary to stop one machine without stopping the rest. It is usual to
drive each machine separately from an overhead shaft by means of belt gear; and
this arrangement also is found convenient, as it admits of the machines being much
out of line.
In the case of its being required to fit a series of furnaces with disconnecting
machines, where the furnaces are almost in line, I sometimes find it convenient to
adopt an arrangement of machine in which the overhead shaft is in most cases
unnecessary, the driving shaft being so placed as to admit of some measure of adjust-
ment both as to line and level. Where the faces of the boilers or furnaces are not
quito level the lines of the shafts may be brought into the same vertical plane by
increasing or diminishing the depth of the facings, while in cases where the shafts
aro in the same vertical plane, but not at the same height, the bearing may be
raised or lowered into the required position, and the pinions adjusted upon their
keys higher or lower as required upon the ends of the fan spindles. The lever gear
is so arranged as to admit of slight differences in line either of the excentric rod or
the connecting rod.
To describe the machine more particularly, the bottom of the fan box is bolted
to the sides of the casing; a bearing or hanger is fixed in such a way upon the fan
box as to admit of adjustment in height. Upon the centre of the shaft an eccentric
is turned, similar to those in my other machines, which through a rod drives a lever
which oscillates upon a fixed centre turning within a bearing. Upon the bottom
end of this lever a cross head slides, the distance of which from the central or neutral
axis is regulated by means of a hand screw, so as to give the connecting rods a
shorter or longer throw as required; these connecting rods are attached one to each
end of the cross head, and work one on each side of a casting, being joined together
in front of the fan box by a pin. This pin works within a gab or bearing, so as to
give motion or not to the ram as desired, and ensures great facility in throwing the
feeding parts out of gear, besides allowing the ram to be instantly removed from

page_text: the box without otherwise stopping the machine. The bevel wheels revolve on
their shaft, sliding easily into and out of gear upon sunk keys or otherwise, this
arrangement enabling them to be readily disconnected, there being a collar upon
which the bosses of these wheels impinge when properly in gear. The pinion which
drives the fan is adjusted for height upon the end of the fan spindle by means of
turned washers and a nut, which also secures the fan firmly in place upon the collar.
Within the spindle end is the grease cup, arranged as was previously described; the
spindle works within the bearing, similar to that in my other machines, but having
a solid bottom, which in this case takes the weight of the fan and spindle, thus
rendering a collar working within the grease cup unnecessary. The fan top works
freely within a hole in the fan box, and is surrounded by a loose ring, as previously
described. The spindle guide is attached to the fan box bottom, and this, together with
the whole of the fan gear, may be entirely removed by slacking the nuts which secure
them. When this is done a clear opening into the furnace is left between the dead
plate and the cover of the fan box, which is amply sufficient for use in all cases as a
man-hole, and renders it unnecessary, except under very exceptional circumstances,
to remove the main casting of the fan box, which can thus always act as a hanger
for the line shaft even when it is necessary to entirely strip it of its other gear for
repairs or other purpose. The removal of the driving shaft with its attendant gear
from below the fan box in this machine enables me to employ the ordinary hinged
fire-door instead of a pair of sliding doors as used in my machines having a driving
shaft below.
In these machines for feeding furnaces it is found that there is a constant tendency
to feed the coal towards one part of the furnace, resulting at the usual speed of the
machine in a constant accumulation of fuel about midway between the dead plate
and bridge. In order to overcome this defect I employ a constantly or periodically
varying speed of fans, which at a slow speed feed towards the dead plate, and as
the speed increases drive the coal onward more towards the bridge. By means of
thus constantly or periodically increasing and decreasing the speed I am able to
distribute upon the grate surface of an unlighted furnace a bed of fuel so evenly
several inches in thickness, that it is difficult to detect any inequalities in its depth
at various points from the dead plate to the bridge, and this mode of supplying fuel
when applied to a lighted furnace not only greatly decreases the frequency with
which the rake requires to be used, but makes the combustion at various points over
the grate surface so constant and so similar as to considerably increase the economy
in the use of fuel.
The mode may be carried into practice in one of the two ways which I am about
to describe; either I may periodically or constantly vary the speed of the engine,
the machines being driven at a speed varying with but bearing a constant relation
to it, or I may vary the speed of the fans or the entire machines independently of
the engine which is driving them, the latter being kept going always at the same
speed or thereabouts. In the first case I prefer to obtain a speed of engine varying
as required by means of the governor. This may be done as follows:-Upon a
pulley, from which by means of a belt or otherwise, the governor, which may be of
any ordinary construction, is driven, is cast a friction wheel, and these two together
are free to revolve upon but independently of the shaft upon which they are fixed,
being driven through a friction disc by a fast friction wheel which is properly keyed
or otherwise secured upon the shaft; thus, the relative motion of these friction
wheels is made to depend upon their respective distances from the centre of the
friction disc. In a convenient position upon the shaft or upon the spindle of the
governor pulley or other adjacent shaft, as preferred, is fixed an eccentric, which
gives motion to a ratchet wheel, to which a pin is attached in such a manner that
its distance from the centre of the wheel may be varied at pleasure. This pin
through an arm gives motion to the bearing or guide in which the spindle of the
friction disc works in such a manner as to traverse the bearing, and together with
it the friction disc, backwards and forwards along a groove or way bar in a line
parallel with the shaft driving the friction wheels; thus, the shaft upon which the

page_text: friction wheel is keyed is compelled first to have a relatively quick and then a
relatively slow motion compared with that of the governor pulley, and as the
governor is so constructed as to run at or about one uniform speed, cutting off steam
when running below its normal rate, the actual result of this arrangement of gear
is to give the shaft, and, together with it, the machine a variable motion, alter-
nately quick and medium and slow, and this variable motion enables the fans
to feed the same amount of coal at the back and front of the furnace as they do in
the middle of its length.
In this method of varying the speed of the fans I may sometimes use a worm and
wheel in place of the eccentric and ratchet wheel, and speed cones and belts in place
of the friction wheels and discs described.
be
In the second case mentioned, in which I keep the speed of the engine uniform,
but vary the speed of the machines with regard to it, as will be useful where the
driving engine is used for other work besides the machines, I use a varying speed
connection between the engine and the shaft driving the machine. This may
done in several ways, one of which is to drive the line shaft from which the machines
are driven by means of cone pulleys from the engine shaft or some shaft having a
uniform motion' derived from it, in such a manner that when the belt is travelled
backwards and forwards within a suitable interval, and by suitable mechanism, across
the surfaces of these cone pulleys, a variable speed will be given to the machines,
while the engine is still kept by means of its governor at the normal rate; this may
be effected either by means of an eccentric crank or cam of suitable form driven by
any mechanism either from the engine shaft or from the shaft driving the
machines.
Another way of effecting this end is to drive a countershaft carrying the driving
pulley by means of a friction wheel keyed on to the engine shaft, but free to slide
backwards and forwards along it; this friction wheel drives through a friction disc
another corresponding friction wheel, also sliding freely upon a sunk key upon the
countershaft carrying the driving pulley. These friction wheels are always kept at
the same distance from one another by means of a suitable link or coupling, which
also serves to move them backwards and forwards across the surface of the friction
disc or discs, so as to vary the speed of the countershaft periodically while the engine
speed keeps uniform. The gear for traversing the friction wheels may be similar to
that formerly described as used for moving the belt across the surface of the cone
pulleys.
In either of the two latter instances I may sometimes keep the work upon the
engine uniform where two or more machines are being driven from it, and arrange
them in such a manner as by separate connections to drive one-half of them quickly
while the other half is being driven slowly.
When the speed of a two-fan machine, as previously described, is varied in this
way so as to oblige it to feed alternately at the dead plate and at the bridge ends of
the furnace, it is found that the angular or rather tangential width of coal spray
required to cover the front end of the furnace is greater than that required to cover
the back, in consequence of the fuel having in the latter case a greater distance to
travel, resulting in a greater dispersion for a given amplitude of spray at the fan
box end. It is therefore necessary that the spray of coal should condense as the
speed of fan increases; this object may be effected in several ways. One of the
simplest plans is to narrow the stream of coal which is being thrust by the ram over
the front edge of the aperture in the fan box top on to the fans, so that no part of
the coal shall fall near their centres, but on the contrary the whole come into
contact with them in the immediate vicinity of their edges; this results in the
instant discharge of the coal, as is subsequently more particularly described, down
the central portion of the furnace, or, in other words, in the required condensation
of spray. To obtain, as the speed of fan increases, a narrowing stream of coal thrust
forward by the ram a simple arrangement of guide plates may be used so fixed that
when drawn towards each other they gradually diminish the opening through

page_text: which the coal passes on to the fans. The necessary motion of guide plates is
obtained by connecting them in any convenient manner with some part of the speed
varying gear, which thus communicates to them the required reciprocation.
Another ineans of condensing the spray as the speed increases is to so construct the
fan beaters that the angles they make with tangents drawn from their points of
contact with the fan's periphery in the direction of its motion shall diminish as the
speed increases. One way of doing this is to cast brackets on the extreme edge of
the fans, so that the beaters may be hinged upon them, and thus admit of their
inner ends being moved forward from the normal position in which the faces of the
beaters are radial from the fan's centres, making various angles with the corre-
sponding radii. If these beaters are now weighted upon their inner ends, but
somewhat forward of their respective radial faces, and a spring be attached to their
backs so as always to tend to keep their faces radial, it will be found that with
increasing speed they will make increasing angles with their normal positions, or in
other words their angles with tangents will decrease; this action results in a more
rapid discharge of the coal from the fan, and a direction of discharge more nearly
down the middle of the furnace.
Another means of obtaining this condensation of spray is to allow those portions
of the coal falling from the sides of the aperture in the fan box top on to the fans
near their centres to come into contact with them in a more backward position, so
as to allow time for its discharge from the beaters at about the same point as that
from which the coal falling in the first instance near their edges is discharged,
resulting as before in the whole of the supply being thrown centrally down the
furnace; this may be effected by means of small shutters or sliding traps in the fan
box cover connected with the speed varying gear in such a manner that as the
speed increases the sides of the aperture obtain a more backward opening.
The speed varying gear previously described may also be usefully employed to
correct the distribution of fans turning on horizontal axes similar to that described
in the Specification of Stanley's Letters Patent, No. 4692, A.D. 1822; this form of
fan, when running at a uniform speed, also gives a ridged bed of coals, but the
defect may be effectually corrected by properly varying its speed. It is however
only applicable to grates which have vertical sides, and where in consequence an
aperture can be made for the injection of the fuel of equal width with the grate
surface.
It may occasionally be found desirable to suit the varying wants of steam users
to feed the fires periodically and not continuously, as is customary with machine
firing; this may be easily done with any of the arrangements of machine described
by suitable mechanism being used to disconnect the driving gear of the rams after
an interval of feeding, and thus while the fans are still working give the fires an
interval of rest, during which they will burn thoroughly through; these intervals
may be of any desired length.
By means of carefully experimenting with the two-fan machine, as described in
my Specification, No. 1257, 1874, herein-before referred to, I have ascertained that
in machines of this class where the coal falls over an edge on to the fans, so that
when it first comes into contact with them some part of the coal is near the extreme
edge of the fan blade, while the rest comes first into such contact at points nearer
the centre of the fan's motion; all the coal, whatever the position of its first contact
with the fans, reaches the extreme edge of the fan blades before it becomes free from
their angular motion; thus, those portions of the coal that fall near the centre of
the fan are carried round its centre in a spiral direction until they have reached the
periphery of the fan, and are consequently outside its influence when they travel
onwards into the furnace in lines nearly tangential with the periphery. The effect
of this action is that the coal which falls on to the fans near the end of the beaters is
driven from them down the centre of the furnace, while the coal which falls on to
them nearer their centres is first turned partially round with them, and then thrown
off in the direction of the furnace sides.
The knowledge of this principle has enabled me to construct a one-fan machine in

page_text: conformity with it in such a manner that it is not only capable of doing the same
work as a two-fan machine, but admits of a certain local control of the supply
travelling outwards from the fans by means of increasing or diminishing it in any
given direction. To effect this object I feed the entire supply of coal upon or very
near to the extreme edge of the fan beaters, in such manner that it immediately
flies off from them in lines tangential with the periphery of the fan disc at or near
its point of first contact, the direction of the coal being but little affected by the
angular motion of the fan, or in other words, not being to any appreciable extent
carried round with it. A fan constructed upon the same principle and driven in
either of the two ways previously described, is placed within a suitable box in any
convenient position in front of the furnace. The coal is allowed to fall upon the
fan over the edge of a segmental table forming the arc of the circle concentric with
the fan. This arc, within which the coal is allowed to fall upon the fan, is in a
position slightly behind (with regard to the direction of the fan's motion) that seg-
ment of the fan's periphery from which it is required that the coal should be
discharged into the furnace. This segment of discharge from the fan is bounded upon
either side by lines radial from the fan centre, and perpendicular to tangents drawn
from the fan's periphery in the direction of its motion so as to bound upon either side
the space within the furnace, over which at any particular time it is desired to
spread the coal. The angular, or rather tangential width of this space over which
the coal must be distributed will vary inversely with the speed at which the fan is
travelling at any particular time, or in other words, will be greater when the fan is
feeding towards the front of the furnace, being then bound by tangents cutting the
extreme corners of the dead plate at its inner edges, and less as the fan feeds towards
the back of the furnace, being when least bounded by tangents cutting the right and
left hand edges of the bridge at the furnace sides. The segmental edge of the table
over which the coal falls upon the fan may either front from or towards the fan
centre, but must be so placed that the fall of coal is around the edge of the fan.
I prefer to feed the coal over this edge by means of a ram plunger or sliding plate
of convenient shape (which will change with the position in which the fan is placed
with regard to the front of the furnace), and may be driven with an adjustable
length of stroke, as previously described, or in any more convenient way from the
driving shaft of the machines.
Means are provided of locally controlling the supply of various portions of the arc,
over which the coal falls upon the fans. This may be done by splitting the edge of
the segmental plate over which the coal is propelled by the ram in the direction of
the ram's motion, and attaching each separate portion of this split "lip" to the
main casting by means of a hinge, in such a manner that each piece of the "lip"
may be separately tilted upwards or downwards to any required degree, so as to
place an obstruction in the way of, or give facility to the forward movement of the
coal over various parts of the surface of the segmental table, as required at different
times and under changing circumstances. Thus, when the coal is being fed towards
the back of the furnace, that portion of it which would otherwise strike against the
sides and rebound irregularly may be reduced in quantity or stopped altogether by
raising those hinged portions of the lip that lay in the path of their supply.
The requisite movement of these lips may be effected in various ways, one of
which is by means of a direct connection with the speed varying gear previously
described, such as a rod reciprocating in such a manner that when the gear is
in a position which gives the machines a considerable speed, it shall raise the
portions of lip described so as to cut off the supply, as required.
The connections between the rod and the movable portions of lip may also be
made variable so that the elevation of lip may be adjusted as required for any
particular speed of fan. Thus, if it is found that the machine is feeding too
much or too little coal upon any particular part of the grate surface by a suitable
alteration of the times or amounts of lifts of the small segments of lip, the requisite
re-adjustment of distribution may be easily effected.
To reduce the amount of dust carried off by the draught into the flues of the

page_text: furnace it is sometimes found useful to slightly damp the coal, as hereafter described.
When this is done the adhesion of the finer particles together into little masses is
greatly assisted by some pressure being exerted upon them. This may be done by
means of a plate hinged in the neck of the aperture, and when closed preventing all
egress of the coal. This plate has an arm and counterwight upon its hinge, so placed
as always to press it downwards.
To feed coal upon the fans the ram must press against this plate with sufficient
force to lift the counterweight, and in so doing compresses the coal dust as required.
In cases where the passage of the dust out of the flues and stack is found a
nuisance, as for example, in glass works and passenger steamers, it may be trapped
This may
by means of its greater momentum than the gases in which it moves.
be done by making the whole of the products of combustion turn sharply round a
corner when the heavier particles will, in consequence of their superior centrifugal
force, be projected to the outside of the curve where they may be easily entrapped
under a shelter, behind which the draught has no access, and where they may freely
deposit themselves through still air. This dust will also deposit itself by means of
its greater specific gravity than that of the gas in which it is suspended if it is
allowed to pass together with the rest of the products of combustion in a broad
shallow stream along a wide deep flue, all draught in the bottom of which is pre-
vented by means of a series of transverse partitions. As the shallow stream of gas
moves along, the dust will readily settle down behind the partitions through the
still air below, into a position in which it can do no harm, and from which it can be
removed at suitable intervals. But the most effectual way of dealing with this
dust is to remove it from the coal before the latter is thrown into the furnace. This
may be done by causing the main stream of coal being brought forward to the
machines by any of the means herein-after described to fall freely through the air
for a short distance. If past this falling stream, a slight current of air is driven either
by steam jets or any more convenient means, that portion of the small coal which
is so finely divided as to be powerfully influenced by draught will be separated
from the rest and may be received into a suitable chamber at one side of the stream
of coal from which this dust has been extracted. If this dust is then treated with
petroleum, tar, or other compound, at the same time glutinous and inflammable, and
afterwards first mixed and then compressed, it can be again discharged into the
travelling stream of coal and carried on with it to the furnaces in a form more con-
venient for the purpose and also more economical than that of finely divided dust.
This object may be effected by means of placing a mixing worm at the bottom of
the chamber in which the dust is received. This worm may terminate in a forcing
end, of taper form, or otherwise, beyond which a short spout or nozzle of small
diameter may conduct the material back to the coal conveying gear.
If the sides of the receptacle in which the dust is received be made to converge
at a suitable angle towards the mixing portion of this worm, and petroleum or
other more suitable material be allowed to fall in small quantities upon it, the
whole will be effectually mixed together, and subsequently forced by the end of the
worm through the small nozzle, within which means may be employed to dry it
if required, on to the travelling gear, where it will break off in convenient sized
pieces and be conducted together with the rest of the coal onwards to the various
machines. It may, however, be in some instances convenient to steam users to
simply extract this dust by the method described, and collect it for sale or other
convenient purpose without immediately utilizing it in the machine, as described.
When a number of furnaces are in a line, or nearly so, with one another, I find
it advantageous to employ a system of constant supply of coal to the machines
direct from the coal waggon or bunker in which the coal is kept, so as to reduce
the amount of labor required for working the fires by superseding all hand working
of the fuel before it is fed into the furnace. I am also able by the same means to
avoid the necessity of keeping a reserve supply of coal above each separate machine,
thus at once getting rid of the usual cumbrous and unsightly hopper. I may effect
this object completely and satisfactorily in several ways. In the first of these I

page_text: use a worm which turns upon a horizontal axis in line, or nearly so, with the
machines. It is enclosed in a case of the usual construction, and carried imme-
diately upon the top of the machines, being seated on the flange of the casting upon
the cover of the fan box, which acts as an enclosure and guide for the plunger or
ram in exactly the same position usually occupied by the hopper.
The bottom of the case for the worm is continuous throughout its whole length,
excepting immediately over the ram, where an opening is left, so that the fuel will
always lie in immediate contact with it. The bunker or hopper in which the
reserve of coal is kept for the whole of the fires stands at one end of the worm
which is constantly withdrawing the coal from it. Below the centre of the worm
this bunker is formed closely round it like the bottom half of the rest of the fan
case, but the sides rise above the worm in diverging directions like two sides of a
very large hopper, and in such a manner as to allow the whole of the coal to
gradually slide down without assistance on to the worm as the latter carries the
coal away from the bottom of it. This bunker with the worm at its bottom may
be of any required length and height, according as a large or small reserve of coal
is wanted.
To avoid a too heavy internal friction between the mass of coal within the
bunker, and the coal being at any moment carried on by the thread of the worm
I provide sheltering plates of suitable forin immediately over the worm, in such a
manner that when they are all closed they form a continuous roof, protecting the
worm from the superincumbent weight. Any one or more of these separate
sheltering plates or shutters may be opened at a time by the man in charge, and
the worm will then withdraw the coal from that portion of the bunker. The
carrying capacity of that portion of the worm which is within the bunker is made
less than that of the main portion of it without the bunker, so as to ensure that the
latter portion of the thread is only lightly fed with coal and thus prevent any
liability to choke within the case. This may be done either by making the worm
within the bunker of less pitch or less diameter than it is without it. The junction
between the bottom of the worm casing and the top of each fan box, previously
described, is so formed that the ram governing the amount of coal withdrawn by
each machine from the stream, being brought over it by the worm, may be said to
work within a small recess or pocket immediately in the bottom of the worm case,
so that it has the moving stream of coal always passing over and by the action of
the worm, being pressed into immediate contact with it.
I sometimes slope the thread of the worm backwards immediately over this
opening, so as to produce a slight downward pressure of coal upon the working face
of the ram.
In cases in which difference of level, or of line, or any local obstruction necessitates
the worm being fixed at a higher level than described, I make the connection
between the openings in the bottom of the case and the fan box tops, within which
the rams work by means of a small parallel pipe not in any way of the nature of a
hopper, or meant for the purpose of holding any reserve supply of coal whatever,
but simply as the most convenient and least cumbrous connection possible. This
pipe, if not parallel, should be rather more open at the bottom than the top to
prevent the possibility of damp or lumpy coal lodging within it, as it is constantly
found to do in the use of the hopper, which is smaller at the bottom than the top.
It is the liability of coal to stick or "arch" within the hopper that has chiefly led
me to see the necessity of getting rid of it in as many instances as possible, as it
has been found a frequent source of annoyance where damp coal must be used.
This liability to "arch" does not occur to any appreciable extent within the
bunker, as previously described, the converging sides being only two instead of four,
the area of contact with the worm being large, and where a number of fires are fed
at once the quantities being dealt with comparatively great.
The relative position
of the worm and ram are such, and the recess containing the ram previously
described is so formed, that when the ram is out of gear and not withdrawing coal
from the worm, the latter, after filling up the recess (which it indeed at all times

page_text: keeps full), carries the rest of the coal onwards over it to those machines (if any)
which are further removed from the coal bunker, and in so doing has no tendency
to force coal on to the fans independently of aid from the rain, which latter has
the sole control of the amount, if any required, to be fed on to the furnace to which
it is attached. Thus it will be seen that my machine, as previously described, is
complete within itself, and in no way affected, altered, or amended by the addition
of the worm, which is also complete within itself, and has its own distinct and
separate office to fulfil.
The condition of each of the machines, with the exception of the one working
furthest from the bunker, is simply that of drawing their supply of fuel from a
stream of coal always passing over them. But the conditions under which the last
machine working receives its supply are somewhat different, inasmuch as the worm
must, through its means, dispose of the entire surplus remaining over after the
wants of the last machine but one have been satisfied.
These conditions may be met in several ways. In the first place, the end of the
thread may be tapered off, and a small hopper made above it in such a manner that,
if the worm brings on more coal than the ram is withdrawing from it, the remainder
may be forced upwards into this hopper, so that when the attendant reduces the
speed of the worm, or otherwise alters the residual supply, should the worm be then
bringing on a quantity less than that required to supply the ram of this last
machine, it may draw what is deficient out of the small hopper before named, so
that the attendant may not have to pay a too constant attention to the adjustment
of the worm's speed.
In the second case, this small hopper may be done away with by giving the ram
always so long a stroke that whatever amount of supply the worm is bringing on
it may at once be discharged into the fire, and the attendant will then regulate the
speed of this machine, not as usual by means of the rain, but by adjusting the
speed of the worm.
But the conditions named may be more thoroughly satisfied by the use of a
mechanical governor, by which the surplus supply being brought on by the worm is
always so controlled as to correspond with the wants of the ram of the last machine
without either excess or deficiency. This may be done by forming a movable lid,
hinged or otherwise, immediately over the end of the worm and ram of the last
machine, so that, when more coal is being brought on by the worm than is being
withdrawn by this ram, the excess may force the movable lid open, and in doing so,
by communicating with the speed adjusting gear through levers or otherwise, may
reduce the speed at which the worm is revolving, and when less coal is being
brought on than is being withdrawn by the ram, and the coal lying in contact with
the movable lid is consequently being undermined, this lid may fall, and by the
same means increase the speed of the worn as is required.
To avoid the necessity of constructing the second governor for use upon the boiler
or furnace next to the end for use on such occasions, as when the end boiler is laid
off for cleaning or repairs, I prefer so to construct the ram of the then last machine
that when in full gear it will, as described, carry all the remainder on to its fans,
and allow the attendant to regulate at those times the feed for this fan by adjusting
the speed of the worm by hand.
This arrangement of horizontal supply may be usefully applied to feeding
machines direct from the bunkers on board ship, and is especially convenient, as in
consequence of the absence of hoppers in most cases all obstruction to opening the
smoke box doors is avoided, and the whole system of furnace feeding rendered
much more compact and convenient. In these cases the worm may be fixed hori-
zontally, immediately above the rams of the machines, as before described, and
continued onwards into each bunker, the ends being tapered off so as to compel
them both to feed the body of the worm lightly, and to discharge the excess of coal
around their axes easily. The driving gear of this worm may be conveniently
arranged upon a continuation of its axis in a recess formed within one of the
bunkers, a tunnel or man-hole underneath the end of the worm giving free access

page_text: to it. The gear by which it is driven may be made reversible, so that the worm
will draw its supply from either bunker as required, or alternately from each.
Over the worm in each bunker and at some distance above it is fixed an adjustable
sheltering plate of such width that the "angles of repose" at which the coal in the
bunker will from either of its edges underlap this plate, will allow the coal to just
lightly lie around and within the thread of the end of the worm in such a manner
that the latter, without being in any way overweighted with coal lying above it,
may yet be able to draw a continuous and even supply across the machines. Any
excess of the supply being brought on by the worm to the machines at any time
will be carried on by the former into the opposite bunker, where that taper end of
the worm will freely discharge it around and above its axis into the space left
underneath the sheltering plate previously described, which will be of triangular
section, base upwards, bounded upon the top by the plate, and upon either side by
the bunker, coal lying at its angles of repose underneath it. As in this respect
each end of the worm is similarly arranged, it will work equally well in one
direction as in the other, and may be thus worked so as to withdraw equal quantities
from each bunker; or, if desired, by working it longer in one direction than in
the other, it may be made to withdraw a larger quantity from either bunker, as
required.
It is sometimes desirable for the sake of compactness and lightness to employ an
arrangement for supply of coal to these machines which will go into a smaller
compass than the worm, which latter to be efficient must be itself of considerable
diameter and weight, enclosed within a still more bulky case, and altogether forms a
considerable obstruction in front of a boiler, besides adding weight to the load on
the boiler front or furnace frame. This may be done by means of a pipe split
longitudinally down the centre in such a manner that the two halves may be free
to reciprocate independently of one another, the bottom half travelling in a forward
direction, while the top half is travelling backwards.
These two separate halves may be reciprocated in alternate and reverse directions
by means of a lever, the centre or fulcrum of which is in the same plane that
divides the pipe into halves. By attaching the top end of this lever to the top half
of the pipe, and the bottom end of the lever to the bottom half of the pipe, and
moving the lever backwards and forwards upon its centre, the necessary reverse
reciprocations of the two halves of pipe are effected. When this pipe contains coal
as the friction between the coal and the bottom half of the pipe is greater than it
is between the coal and the top half, the former will always be carried in that
direction in which the bottom half is moving. When the lever has reached the end
of its stroke, carrying together with it the bottom half of the pipe and the coal
that it contains in the direction in which it is required, and the top half of the
pipe backward in the opposite direction, this whole arrangement of pipe lever and
connections is by suitable gear inverted, so that what was the top half and is in its
backward position becomes the bottom half, and consequently that on which the
load of coal rests and what was the bottom half becomes the top half, and is free
to move backward without carrying the coal backward with it. Then the return
stroke of the lever and halves of pipe is effected, the coal being moved onwards by
similar means, and in the same direction as before.
The driving of this mechanism may be effected by means of a reciprocating bar
and clutches so arranged that in its forward stroke it takes hold upon the lever and
gives it and the pipe the required reciprocal motion, while in its backward or return
stroke it gives motion to the mechanism (spur gear or otherwise), which inverts the
pipe and lever gear as described. The end of this pipe within the bunker will, by
the simple alternate motion of its halves, scoop out the coal and carry it onwards
as required. The junction of the pipe with each of the machines, excepting the
last one, is effected by making a sufficiently large hole in the bottom of each half
pipe, which, at the back end of its stroke, is immediately over the ram of the
machine it is feeding.
The end machine may be fitted in any of the three ways described as used in the

page_text: case of the worm feed, but when using the first or third of those methods the end of
the pipe is thickened and formed into a forcing ram, so as to compel the coal to
enter as required. The longitudinal joint of this pipe may be formed to prevent
leakage of coal by lapping each side of each half pipe well round the corresponding
side of the other half in such a direction that the inside edge never faces the
direction of the pipe's motion when being inverted.
A third method of supply, and one which, measured vertically, goes into a still
smaller compass, consists of of a continuous band travelling over pulleys and carrying
the coal across the machine upon its upper surface in a manner similar to that in
use in corn mills and warehouses for grain or flour. In this manner the band is
made to bring a continuous stream of coal from the waggon or bunker over the top
of each fan box and immediately in front of the port through which the fuel is forced
by the rams on to the fans. The ram is arranged to travel backwards and forwards
in front of the port and over the travelling band, and in its forward movement
pushes some of the coal off the band through the port. In its backward movement
it is so formed (on a similar principle to the tool holder of a planing machine), as to
slide over the stream of coal without disturbing it. Where the driving shaft of the
machines is fixed over the fan box this ram or scraper may be actuated from it, and
it will then be found convenient to make the upper part of it from which the ram or
scraper hangs also form the top of the channel through which the coal is forced on
its way to the fans. The length of stroke or the vertical dip of the ram or scraper
may be made adjustable, so that it will withdraw from the passing stream of coal at
each stroke any desired quantity. Should it be found desirable to stop the band
during the passage of the scraper this may be done by a ratchet gear, or otherwise,
In this way
giving it an interval of rest alternately with an interval of motion.
any required number of machines may be made to withdraw their supply from the
thin stream of coal being carried over each of them in their order by the travelling
band. The surplus supply may either be dealt with in one of the ways previously
described as applicable to my arrangement of worm or split pipe, or may be dis-
charged on to the returning part of the belt and carried back again to a point near
the bunker, where it may again be discharged into the bunker or receptacle from
which the coal is being withdrawn, or on to the feeding part of the belt, adding to
the supply being withdrawn from the bunker. Thus even in the event of the man
in charge carelessly stopping the feed of all the machines while the travelling band
was still drawing a full supply from the bunker no harm would ensue.
Should all the machines that require to be fed from this one stream of coal not be
in line with one another the band may either be made to discharge its coal upon
another band taking the required direction across part of the machines, or by means
of a system of pulleys common in corn warehouses, the original band may first be
bent downwards and backwards so as to discharge its load of coal into a small guide
or shoot, and then by means of other pulleys given the required new direction, then
passing immediately under the shoot or spout before named, again receive its load of
This method of
coal and carry it straight onward to the succeeding machines.
supplying the machines with fuel has the advantage of never breaking the coal
as the worm is found to do in some degree, especially where great lengths are
used.
The band may be also made to withdraw its supply from any distance and
from any position, and will carry its load up or down an incline of from 20
to 28 degrees. It may be loaded direct from the bunker either by simply
passing under an open coal spout in the manner adopted for carrying flour, or
to avoid excessive wear and tear it may be gradually fed by a plunger, or
rollers, or a crusher, where it is convenient to use such apparatus. It may be
either partly or wholly enclosed in a case so as to prevent air being sucked in
through the coal passages in the machines, or when this is undesirable a light
hanging screen or shutter may be placed on each side of the plunger in such a
manner that while not interfering with the coal upon the band it yet practically
closes the passage against air, Thus my principle is to withdraw the supply

page_text: for furnaces, not from local reserves, as that contained in a hopper above them,
but from a constantly passing stream of coal brought forward from the main bunker,
crushing apparatus, or coal truck, by any convenient mechanical means, three of
which have already been described, and I thus avoid much labor, which would
otherwise be expended in handling the coal, and remove a source of dirt and annoy-
ance from the stoke-hole
Where it is desirable to use large coal I crush it to the required size at the source
of its supply before it is brought forward by the worm, pipe, or travelling band, and
for this purpose I prefer to use a crusher working somewhat upon the principle of
what is known as Blake's stone crusher, but as it is an object to prevent the formation
of dust I preferably make both the crushing jaws of open structure and not of solid
plate, so that when in the upper part of the jaws pieces of coal are broken up small
enough for my purpose they may be at once free to disengage themselves from the
crusher, either through the aperture between these jaws at the bottom in the usual
manner, or through the structure of the jaws themselves. This may be done by
forming each jaw of a strong framework within which can be placed at suitable
distances apart vertical knives of steel or other hard metal, which if broken or worn,
can be easily replaced.
The crushing gear may be easily driven by the same gear which actuates the coal
conveying gear and furnace-feeding machine. Arrangements of this kind are par-
ticularly applicable to steamships which when coaling at foreign stations can only
obtain large coal.
Where it is desirable that the rams or scrapers should have a long slow traverse,
as when used with a travelling band, they may be driven separately from the
driving gear of the fans, and at a slower speed. This may be easily done by means
of a reciprocating rod or rocking shaft arranged in a convenient position and con-
nected with the rams or scrapers of all the machines, the whole being driven by
suitable gear direct from the engine or countershaft.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Joseph John Butcher in the Great Seal Patent Office on the 26th
March 1878.
JOSEPH JOHN BUTCHER, of Gateshead, in the County of Durham, Engineer.
"IMPROVEMENTS IN APPARATUS OR MEANS FOR SUPPLYING FURNACES WITH FUEL,
AND IN FURNACE FLUES."
My present improvements have reference to apparatus, commonly called mechanical
stokers, for supplying fuel to furnaces; also to means of preventing coal dust being
carried by the draught out of the chimney or stack of furnaces.
According to one part of my Invention I construct mechanical stokers with tho
driving shaft below the machine, as seen at a, a, in Figure 1 of the annexed
Drawings, above which shaft, which is driven in any convenient way, is a box A
containing two fans b, b, rotating as usual in a horizontal plane, these fans being
supported entirely from below, each upon a spindle c, which rests upon a collar
supported within a vertical bearing d, secured to the bottom of the fan box e, as
shewn. This spindle c, together with the fan b, is driven by the spur wheel f, placed
upon the driving shaft a, through the pinion g, securely fixed upon the bottom end
of the spindle c, as shewn.
I also sometimes use friction wheels and discs in place of the bevel gear, in which
case the collar upon the fan spindle c is done away with, the weight of the fan and
spindle being supported upon the friction disc which is secured to the bottom of the
spindle, as shewn in the Drawing attached to the Specification of Letters Patent
granted to me on the 11th April 1874, No. 1257.
I sometimes find it convenient to use a gear combining the advantages of both
those named. The edge of the pinion g (see Figure 4) is so extended as to form a
friction disc, and the edge of the web of the bevel wheel f is broadened and faced
in a lathe so as to act against the under side of the lip upon the pinion just described.
In this form of gear the collar upon the fan spindle is also done away with, the
weight of the fan and spindle being supported, as in the case of the friction gear,
through the friction lip upon the pinion g upon the friction edge of the wheel f
The peculiar advantage of this form of gear is that while it possesses all the
certainty of action of ordinary bevel gear, it is yet almost as noiseless as friction
gear, as the teeth of the wheel and pinion never come into working contact except
when the friction between the edge and lip is insufficient to drive the fan alone,
and even in this latter case the jar is much softened by the resistance to movement
caused between the friction surfaces.
The attachment of the fan b to the spindle c may be effected in either of two
ways, both of which have been found to give the necessary rigidity.
Either the top of the fan may be driven tightly down over the enlarged top h,
Figure 1, of the spindle upon the collar j, as shewn; and secured in its position by a
nut upon the spindle end, or it may be drawn down upon a cone h, Figure 4, upon
(turned upon) the end of the spindle c by means of a nut upon the spindle end, as
before.
In either case the spindle end c is enlarged and bored out, as shewn in dotted
lines, so as to form a tallow cup, from the bottom of which a channel conducts the
lubricant to an annular grease reservoir in the spindle guide d, as shewn.
Upon the centre of the shaft a, midway between the bevel wheels f, f, is turned
an eccentrick, Figures 2, 4, and 5, driving an eccentric strap, the wear in which is
easily taken up by means of the loose block and set pin. A rod m is screwed
into this strap, as shewn, at the other end of which is formed a gab n, Figure 2, and
ball weight. This gab rides upon two pins turned upon the bottom ends of the
levers o, Figures 1 and 2, which swing upon the centre pin p, and through them
drives the ram or plunger q to which the levers are attached by means of the pin r.
The centre pin p, forming the fulcrum upon which the levers o swing, is free to turn
within a block which can be moved up or down the slot in the bracket 8 at pleasure,

page_text: The ends of this pin are squared and free to move up or down through the slots in
levers o, and at each end of the pin beyond the square is fixed a small handle to
enable the man in charge to raise or lower the centre pin. From the bottom of the
block within the bracket s hangs a pin t which passes through a hole drilled in the
bottom of the bracket 8, and serves to enable the man in charge, by means of the set
pin u, to clamp the block fast in any required position. This movable centre to the
levers o enables them to be adjusted to any required length of stroke, the ram
having a small traverse when the pin is at the top of the slots, and a large traverse
when it is at the bottom, the amount of coal fed by the ram q through the aperture
von to the fans b being correspondingly less or greater.
I sometimes find it convenient to make the feed adjustable by means of a screw
so placed as to raise or lower the block and centre pin p, Figure 5, on which the
levers o swing. In this case I prefer to arrange the screw w, see Figure 8, within
the slot in the central fixed bracket 8, Figures 4 and 5, and 7, 8, and 9, cutting a
corresponding thread within the block through which it passes, and slotting out
the pin y in such a manner as to allow these parts to pass freely over one another
without contact. This centre pin has squared ends, as before, but the handles beyond
them are unnecessary. The eccentric rod m, Figure 5, gives motion to the levers o
by the eye n through a pin and eyes. The top ends of the levers o give motion to
the ram q through pins which are made in a piece with them, and project into and
are free to turn within the eyes which are attached to or in a piece with the
ram q.
I may sometimes make the block solid (see x, Figures 10 and 12), with a pin
projecting from it on each side into and free to revolve within a small bearing a, a,
Figure 12, with flat sides sliding within the levers (o, Figures 10, 11, and 12). The
special advantages of these screw-adjusted levers are extreme ease of handling and
great variety of feed caused by the long slots they admit of, and by their means,
when required, a fire may be thoroughly "banked" or damped down in a few
minutes without any coal having been put on by hand. When the centre pin is at
the top of the slot, the stroke of the ram is so short as to be practically ineffective;
but in case of any inconvenience being caused by this small traverse of rain I some-
times slightly open the slots at the tops of the levers in such a manner as to allow
of the ends of the pin (y, Figures 8 and 9) playing freely within it without coming
into contact with the sides of the slot, and in this way leave the ram q entirely
without motion. This allows me to replace the gab in the eccentric rod m without
an eye n, which not only wears longer, but admits of the slots being so lengthened
downwards as to give the long traverse of ram before mentioned.
The cover of the fan box B is cast in a separate piece and fitted on to its place,
and upon it, as shewn at B', Figure 5, a suitable recess or pocket is formed for the
reception of the ram and the coal immediately contiguous to it. At the side of this
pocket, which is opposite to the ram, is formed a channel through which the coal is
forced by the ram in the direction of the edge C, over which it falls on to the fans,
which project it in the usual way on to the fire.
The channel B, Figures 2 and 3, I sometimes make separate from the main
casting of the box cover, and so arrange it that it is free to slide along a line cutting
the two fan centres so as to enable me to adjust upon each fan, and throw the coal
upon either side of the furnace or centrally, as required.
To effect this purpose I
either use a hand screw or lever or other suitable gear attached to the side of this
sliding channel, so that it may be set to any desired position at will.
The tops of the fans b, Figure 4, pass up through holes cast in the box cover,
which are larger in diameter than themselves, a practically air-tight joint being
formed by means of the loose ring 2, which has a sharp edge on the inside and fits.
closely, but not tightly, around the fan top. Within this ring the fan turns freely,.
while the former lies at rest upon the fan box top. This arrangement allows of little
inaccuracies in fitting, and thus much reduces the cost of manufacture.
This machine, as above described, is complete in itself, and may be driven in any
convenient way from the end of the fan-driving shaft a. Where the flues to which"

page_text: they are affixed are very exactly in line with one another, as in the furnaces of a
marine boiler with two or four flues, it is customary to couple the shafts driving
directly from one end or some other convenient point from the crank shaft of an
engine. As however where a line of boilers is fed by these machines, it is often
necessary to stop one machine without stopping the rest, it is usual to drive each
machine separately from an overhead shaft by means of belt gear (see D, Figure 4),
and this arrangement also is found convenient as it admits of the machine being
much out of line.
In the case of it being required to fit a series of furnaces with disconnecting machines
where the furnaces are almost in line, I sometimes find it convenient to adopt the
arrangements of machine shewn in (Figures 13 to 24). Here the overhead shaft is
(in most cases) unnecessary, the driving shaft a, a, being so placed as to admit of
Where the faces of the
some measure of adjustment both as to line and level.
boilers or furnaces are not quite level, the lines of the shafts may be brought into
the same vertical plane by means of increasing or diminishing the depth of the
facings b, b, while in cases where the shafts are in the same vertical plane, but not
at the same height, the bearings c, c, may be raised or lowered into the required
position, and the pinions e, e, adjusted upon their keys higher or lower, as required,
upon the ends of the fan spindles f. f. The lever gears are so arranged as to admit
of slight differences in line either of the excentric rods g, g, or the connecting
rods h, h.
To describe these machines more particularly:-In the arrangement shewn in
Figures 23 and 24 A is a fan box, the bottom of which is bolted to the sides of the
casing in the manner shewn at Figures 15 and 17. Upon the centre of the shaft a
an eccentric is keyed, which through the rod g drives the lever k, which oscillates
upon the fixed centre I, turning within the bearing m, which may be made separate
from the box if desired, and fitted thereon. Upon the bottom end of this lever a
cross head n slides, which is shewn more distinctly in dotted lines in Figure 23,
the distance of which from the centre or neutral axis is regulated by means of the
hand screw o, so as to give the connecting rods h, h, a shorter or longer throw, as
required. These connecting rods h, h, are attached one to each end of the cross
head n, and work one on each side of the casting A¹, being joined together in front
of the fan box by the pin p, p. This pin works within the gab or bearing in the
ram q, so as to give motion or not to it, as desired, and ensures great facility in
throwing the feeding parts out of gear, besides allowing the ram to be instantly
removed from the box without otherwise stopping the machine. Upon the shaft a
the bevel wheels revolve, sliding easily into and out of gear upon sunk keys or
otherwise, an arrangement similar to that shewn in Figures 15 and 16, and herein-
after described, enabling them to be readily disconnected. The pinions e, e, are
adjusted for height upon the end of the fan spindle by means of the turned washers
r, r, and nuts shewn above them, which also secure the fan firmly in place upon a
collar. Within the spindle end f, f, is the grease cup, arranged as was previously
described. The spindle works within the bearing similar to that in my other
machines, Figures 1 to 6, but having a solid bottom, which in this case takes the
weight of the fan and spindle, thus rendering a collar working within the grease
cups unnecessary. The fan top works freely within the hole in the fan box,
and is surrounded by a loose ring 8, 8, as previously described. The spindle guido
is attached to the fan box bottom, as shewn in the earlier Figures, and this together
with the whole of the fan gear may be entirely removed by slacking the bolts
securing the fan box bottom. When this is done a clear opening into the furnace is
left between the fan box cover and the dead plate, which is amply sufficient for
use in all cases as a man-hole, and renders it unnecessary, except under very excep-
tional circumstances, to remove the main casting of the fan box A, which can thus
always act as a hanger for the line shaft a, even when it is necessary to entirely
strip it of its other gear for repairs, &c. The removal of the driving shaft with its
attendant gear from below the fan box in this machine enables me to employ the

page_text: ordinary hinged fire-door instead of a pair of sliding doors, as used in my machines
which have a driving shaft below.
Figures 15 to 20 shew another arrangement of my machine that even more com-
pletely fulfills the required conditions. Here the fan spindles, Figure 15, preferably
turn within a guide fixed to the top of the fan box, and are supported by a foot-
step upon the fan box bottom, which is bolted to the sides of the casing, as pre-
viously described. The bevel wheels t, t, impinging when in gear upon the collars t¹,
slide upon sunk keys upon the shaft a, and are thrown into and out of gear with
the pinions e, e, by means of the handle u and the links and clutches to which it is
attached, as seen in Figures 15 and 17. The shaft a runs within bearings c, which
are hung upon the worm case (Figures 16 and 17), which itself must be level. The
pinions e, e, are adjustable for height by keys upon the spindles f. f. The rocking
ram B, described in the Specification of my Letters Patent, No. 1257 of 1874, is here
adopted, as it specially meets the requirements of the worm.
It is driven through
the crank and eccentric gear shewn in dotted lines in Figures 16 and 17. Figures
18, 19, and 20 are enlarged views of the gear. The eccentric j, half of which is
preferably cast in one piece with the hanging rod g, swings freely up and down
upon the centres v, Figures 18 and 20. These centres are attached by rods w to
fixed bearings x, x, Figures 18 and 19, and thus the centres v are always main-
tained at the same distance from the fixed bearings x. The eccentric rod g is
grooved out, and within it slides the block y, Figure 20, the position of which is
regulated by means of the screw and hand wheel, Figures 15, 18, and 20. The
block carries a centre y¹, which drives the connecting rod h, crank 'h', and rocker B.
The amount of feed is governed by the traverse of this rocker, which will be greatest
when the block y is at the top of the grooved rod g; as this block is moved down
the groove by means of the hand screw z, the rocker has a less traverse, and when
the centre y is in line with the centres v, v, the rocker B is maintained at rest, while
the eccentric is in free motion owing to the fact that the rods h and w, w, are of
corresponding length, and the centres of the bearings x, x, are in line with a point in
the path of the centre of the crank pin, which is therefore compelled to correspond
to fixed centres.
In these machines for feeding furnaces there is a constant tendency to feed the
coal towards one part of the furnace, resulting at the usual speed of the machine in
a continuous accumulation of fuel about midway between the dead plate and bridge.
In order to overcome this defect I employ a constantly varying speed of fans, which
at a slow speed feed towards the dead plate, and as the speed increases drive the
coal onward more towards the bridge. By means of thus periodically increasing
and decreasing the speed I have been enabled upon the grate surface of an unlighted
furnace to distribute a bed of fuel so evenly several inches in thickness that it was
scarcely possible to detect any inequalities in its depth at any points from the dead
plate to the bridge, and this principal when applied to a lighted furnace not only
greatly decreases the frequency with which the rake requires to be used, but makes
the combustion at various points over the grate surface so constant and so similar
as to considerably increase the economy in the use of fuel.
This mode may be carried into practice in one of the two separate ways which I
am about to describe; either I may periodically or constantly vary the speed of the
engine, the machines being driven at a speed varying with, but bearing a constant
relation to it, or I may vary the speed of the fans or the entire machines
independently of the engine which is driving them, the latter being kept going
always at the same speed or thereabouts. In the first case I prefer to obtain a speed
of engine varying as required by means of the governor. This may be done as
follows: Upon the pulley a, Figure 28, from which, by means of a belt or otherwise,
the governor, which may be of any ordinary construction, is driven, is cast a friction
wheel b, and these two together are free to revolve upon but independently of the
shaft upon which they are fixed, being driven through the friction disc (c) by the fast
friction wheel (d), which is properly keyed or otherwise secured upon the shaft (e).
Thus the relative motion of these friction wheels is made to depend upon their

page_text: In a convenient
.respective distances from the centre of the friction disc c.
position upon the shaft e or upon the spindle of the governor pulley or other
adjacent shaft, as preferred, is fixed an eccentric f, which gives motion to a ratchet
-wheel g to which a pin h is attached. This pin through the connecting rod j
.gives motion to the bearing or guide k in which the spindle of the friction disc c
works in such a manner as to traverse the bearing, and together with it the friction
disc backwards and forwards along the grooves in a line parallel with the shaft
driving the friction wheels. Thus the shaft upon which the friction wheel is keyed
is compelled first to have a relatively quick and then a relatively slow motion
compared with that of the governor pulley; and as the governor is so constructed as
to run at or about one uniform speed, cutting off steam when running above its
normal rate, and opening the steam valve when running below its normal rate, the
actual result of this arrangement of gear is to give the shaft e, and together with
it the machines, a variable motion alternately quick and medium and slow, and this
variable motion enables the fans to feed the same amount of coal at the back and
front of the furnace as they do in the middle of its length.
In this method of varying the speed of the fans I may sometimes use speed cones
and belts in place of the friction wheels and discs described.
Figures 26 and 27 shew a more complete arrangement of speed-varying gear
attached to an engine and governor.
Here the disc c and bearing k are stationary,
and the friction wheels b and d slide upon sunk keys across its face. The wheel d
is keyed upon and driven by the shaft e; the wheel b is keyed upon a hollow
spindle b¹, which runs over the shaft e in the reverse direction, and drives the
pulley a connected by belt with the governor m. The fork n guides the friction
wheels b and d, and is itself driven by the connecting rod o, by the adjustable
crank p. This crank is driven by a train of worm and wheel and spur gear from
the crank shaft e, as shewn.
In the second case mentioned, in which I keep the speed of the engine uniform,
but vary the speed of machines with regard to it, as will be useful where the
driving engine is used for other work besides the machines, I use a varying speed
connection between the engine and the shaft driving the machines. This may be
done in several ways, one of which is to drive the line shaft from which the
machines are driven by means of cone pulleys from the engine shaft, or some shaft
having a uniform motion derived from it in such a manner that when the belt is
travelled backwards and forwards within a suitable interval, and by suitable
mechanism across the surfaces of these cone pulleys, a variable speed will be given
to the machines, while the engine is still kept by means of its governor at the
normal rate. This may be effected by means of an eccentric crank or cam of
suitable form driven by any mechanism, either from the engine shaft or from the
shaft driving the machines.
Figure 25 shews such an arrangement. Here the driving shaft A carries a pair
of cones, each of which drives half of the machines deriving their motion from it.
The forks a and guides b traverse the belts across the faces of the cones, so that the
cone B is going quickly when the cone C is going slowly. The guides b, b, are
driven through the worm and wheel c and d, communicating through the crank
pin e and pair of connecting rods f with the two bell-crank levers g and h, moving
upon the fixed centres g₁ and h', which may be supported in any convenient
manner. The shafts D and E drive reciprocally the two sets of machines, so that
the work upon the engine may be at all times constant.
Another way of effecting this end is represented in Figure 29, and is to drive a
countershaft a, carrying the driving pulley b by means of a friction wheel e keyed
on to the engine shaft f, but free to slide backwards and forwards along it. This
friction wheel drives through a friction disc d, another corresponding friction
wheel c, also sliding freely upon a sunk key upon the countershaft carrying the
driving pulley. These friction wheels are always kept at the same distance from
one another by means of a suitable link or coupling 9, which also serves to move

page_text: them backwards and forwards across the surface of the friction disc or discs d, d¹, so
as to vary the speed of the countershaft periodically, while the engine speed keeps
uniform. The gear for traversing the friction wheels may be similar to that
formerly described, as used for moving the belt across the surface of the cone
pulleys; h (Figure 29) is a small pulley keyed upon the crank shaft f, which
drives by means of a belt the large pulley h, shewn behind it. The latter drives
the worm and worin wheel k through a countershaft shewn in dotted lines. The
worm wheel k carries a crank pin k¹, moving within a slot in a lever, which turns
upon a fixed centre at the bottom, and communicates its motion through a link
shewn by dots at m to the coupling clutch g. The friction discs d and d' are
pressed together by means of the weights n, n, above them.
I may sometimes keep the work upon the engine uniform where two or more
machines are being driven froin it, and arrange them in such a manner as by
separate connections to drive one half of them quickly, while the other half is being
driven slowly.
When the speed of a two-fan machine, as previously described, is varied in this
way, so as to oblige it to feed alternately at the dead plate, and at the bridge ends
of the furnace it is found that the angular tangential width of coal spray required
to cover the front end of the furnace is greater than that required to cover the back,
in consequence of the fuel having, in the latter case, a greater distance to travel,
resulting in a greater dispersion for a given amplitude of spray at the fan box end,
it is therefore necessary that the spray of coal should condense as the speed of fan
increases. This object may be effected in several distinct ways:-One of the simplest
plans is to narrow the stream of coal, which is being thrust by the ram over the
front edge of the aperture in the fan box top on to the fans, so that no part of the
coal shall fall near their centres, but on the contrary the whole come into contact
with them in the immediate vicinity of their edges. This results in the instant
discharge of the coal, as is subsequently more particularly described, down the
central portion of the furnace, or, in other words, in the required condensation of
spray. To obtain, as the speed of fan increases, a narrowing stream of coal, thrust
forward by the ram, a simple arrangement of guide plates, see a, a, Figures 30
and 31, may be used, so fixed that when drawn towards each other they gradually
diminish the opening through which the coal passes on to the fans. The necessary
motion of guide plates is obtained by connecting them in any convenient manner
with some part of the speed-varying gear, which thus communicates to them the
required reciprocation.
In Figures 30 to 32 a mode of connecting such guide plates with the speed
varying gear is shewn. Each plate a, Figure 30, swings upon a spindle which is
moved by a small lever outside the box. These levers turned in opposite directions
are connected by a link b, Figures 30 and 31, in such a manner that when the latter
is drawn in one direction the plates are opened, while when it is drawn in the other,
they will be closed. These levers and plates are actuated by means of the rod c,
Figures 30 and 31, which is driven from the speed-varying gear. In this machine
the fans are driven as formerly described, and the ram, which is in this instance not
required to govern the amount of feed, is driven by the rocking shaft e by the lever
and connection f. The mode shewn in this Figure of supplying coal by band and
scraper is herein-after described.
Another means of condensing the spray as the speed increases is to so construct
the fun beaters that the angles they make with tangents drawn from their points of
contact with the fan's periphery in the direction of its motion shall diminish as the
speed increases. One way of doing this is to cast brackets upon the extreme edge
of the fans, so that the beaters may be hinged upon them, and thus admit of their
inner ends being moved forward from the normal position in which the faces of the
beaters are radial, or nearly so, from the fans' centres, making various angles with the
corresponding radii. If these beaters are now weighted upon their inner ends, but
somewhat forward of their respective radial faces, and a spring be so attached to
their backs as always to tend to keep their faces radial, it will be found that with

page_text: or in
increasing speed they will make increasing angles with their normal positions;
other words, their angles with tangents will decrease. This action causes a more
rapid discharge of the coal from the fan, and a direction of discharge more nearly
down the middle of the furnace.
Figures 33 and 34 are a sectional elevation and plan of such a fan; a, a, are hinge
pins fixed into the fan disc A. and upon which the beaters b, b, turn. In the position
shewn their working faces are nearly radial and are retained so by means of the
light springs c, c, at their backs. As however the centre of equilibrium of these
beaters is in each case forward of a radius cutting the pins a, a, they tend when the
fan revolves to open out forward, and the angles their faces make with radii will be
greater as the speed of fan increases.
Another means of obtaining this condensation of spray is to allow those portions
of the coal falling from the sides of the aperture in the fan box top on to the fans
near their centres to come into contact with them in a more backward position so as
to allow time for its discharge from the beaters at about the same point as that
from which the coal falling in the first instance near their edges is discharged,
resulting as before in the whole of the supply being thrown centrally down the
furnace; Figures 35, 36, and 37, shew au arrangement including this adjustment b, b ;
Figures 36 and 37 are shutters or small sliding traps in the fan box cover, connected
with the speed-varying gear, as shewn in the Figures, by means of rocking shaft c,
lever f, and connections, in such a manner that as the speed increases the sides of
the aperture obtain a more backward opening.
The plates b, b, are separately hinged near the centre of the opening in the fan
box, as shewn in plan, and are drawn forward by the levers f, f, as the speed
increases.
The other parts, for which in the Drawing it has been for convenience surrounded,
are, d, a rocking bottom withdrawing coal from above it, and thrusting it over the
edge a and plates b, b. It is driven by means of a crank and lever gear similar
to those previously described. Above is a worm described in another part hereof,
and the fan gear is like that shewn in Figures 15 to 17.
The speed-varying gear previously described may also be usefully employed to
correct the distribution of fans turning on horizontal axis, similar to that described
in the Specification of Stanley's Letters Patent, No. 4692, A.D. 1822. This form of
fan when running at a uniform speed also gives a ridged bed of coal, but the defect
may be effectually corrected by properly varying its speed. It is however only
applicable to grates which have vertical sides, and where in consequence an
aperture can be made for the injection of the fuel of equal width with the grate
surface.
Figures 38 and 39 shew such a machine; A is a fan revolving upon a horizontal
axis a, a. The coal is withdrawn from the feeding gear, which may be of any
of the kinds specified, by means of the rocker B actuated by the crank b, which
may be driven with an adjustable length of stroke as previously described in other
cases.
The fan may be driven either by pulley or coupling to the shaft driving other
machines.
The crank may be driven from this shaft, or preferably from a separate one
driven at a slower speed.
It may be occasionally found desirable to suit the varying wants of steam users
to feed the fires periodically and not continuously as is customary with machine
firing. This may be easily done with any of the arrangements of machines
described by suitable mechanism being used to disconnect the driving gear of the
rams after an interval of feeding, and thus while the fans are still working give
the fire an interval of rest during which they will burn thoroughly through. These
intervals may be of any desired length.
By means of carefully experimenting with my two-fan machines, as described in
my Specification, No. 1257, 1874, herein-before referred to, I have ascertained that
in machines of this class, where the coal falls over an edge (as at d, d, Figures 31, 36,

page_text: and 37) on to the fans, so that when it first comes into contact with them some part
of the coal is near the extreme edge of the fan beater, while the rest comes first
into such contact at points nearer the centre of the fan's motion, all the coal, what--
ever the position of its first contact with the fans, reaches the extreme edge of the
fan blades before it becomes free from their angular motion. Thus those portions of
the coal that fall near the centre of the fan are carried round its centre in a spiral
direction until they have reached the periphery of the fan and are consequently
outside its influence when they travel onwards into the furnace in lines nearly
tangential with the periphery. The effect of this action is that the coal which falls
on to the fans near the end of the beaters is driven from them down the centre of
the furnace, while the coal which falls on to them nearer their centres is first turned
partially round with them, and then thrown off in the direction of the furnace
Bides.
The knowledge of this principle has enabled, me to construct a one-fan machine
in conformity with it in such a manner that it not only is capable of doing the
same work as a two-fan machine, but admits of a certain local control of the
supply travelling outwards from the fans by means of increasing or diminishing it
in any given direction. To effect this object I feed the entire supply of coal upon
or very near to the extreme edge of the fan beaters, see a, Figure 40, in such manner
that it immediately flies off from them in lines tangential with the periphery of the
fan disc at or near its point of first contact, the direction of the coal being but
little affected by the angular motion of the fan, or in other words not being to any
appreciable extent carried round with it. A fan constructed upon the saine principle
and driven in one of the two ways previously described is placed within a suitable
box, see A, Figures 40 to 42, in any convenient position in front of the furnace.
The coal is allowed to fall upon the fan over the edge of a segmental table forming
the arc of a circle concentric with the fan. This arc, within which the coal is
allowed to fall upon the fan, is in position slightly behind (with regard to the
direction of the fan's motion) that segment of the fan's periphery from which it is
required that the coal should be discharged into the furnace. This segment of
discharge from the fan is bounded upon either side by lines radial from the fan
centre, and perpendicular to tangents drawn from the fan's periphery in the direction
of its motion, so as to bound upon either side the space within the furnace, over
which at any particular time it is desired to spread the coal. The angular or rather
tangential width of this space, over which the coal must be distributed, will vary
inversely with the speed at which the fan is travelling at any particular time, or in
other words will be greater when the fan is feeding towards the front of the furnace,
being then bounded by tangents cutting the extreme corners of the dead plate at
its inner edge, and less as the fan feeds towards the back of the furnace, being when
least bounded by tangents cutting the right and left hand edges of the bridge at the
furnace sides. The segmental edge of the table over which the coal falls upon the
fan may either front from or towards the fan centre, but must be so placed that the
fall of coal is around the edge of the fan.
I preferably feed the coal over this edge by means of a ram plunger or sliding
plate of convenient shape (which will change with the position in which the fan is
placed with regard to the front of the furnace), and may be driven with an adjustable
length of stroke, as previously described, or in any more convenient way, from the
driving shaft of the machines.
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Means are provided of locally controlling the supply at various portions of the
arc, over which the coal falls upon the fans. This may be done by splitting the.
edge of the segmental plate on which the coal is propelled by the ram in the
direction of the ram's motion, and attaching each separate portion of this split "lip
to the main casting by means of a hinge in such a manner that each piece of the
lip" may be separately tilted upwards or downwards to any required degree, so as
to place an obstruction in the way of or give facility to the forward movement of
the coal over various parts of the surface of the segmental table, as required at
different times, and under changing circumstances. Thus, when the coal is being

page_text: fed towards the back of the furnace, that portion of it which would otherwise strike
against the sides, and rebound irregularly, may be reduced in quantity, or stopped
altogether, by raising those hinged portions of the lip that lay in the path of their
supply.
The requisite movement of these lips may be effected in various ways, one of
which is by means of a direct connection with the speed-varying gear previously
described, such as a rod reciprocating in such a manner that when the gear is in a
position which gives the machines a considerable speed it shall raise the portions of
lip described, so as to cut off the supply as required.
The connections between the rod and the movable portions of lip may also
be made variable, so that the elevation of lip may be adjusted as required for any
particular speed of fan. Thus, if it is found that the machine is feeding too much
or too little coal upon any particular part of the grate surface, by a suitable alteration
of the times or amounts of lifts of these small segments of lip the requisite re-
adjustment of distribution may be easily effected.
Figures 40, 41, and 42 shew a one-fan machine embodying this part of my
Invention. The rocker A withdraws coal from the neck above, fed by any of the
means described. The amount of feed is here preferably regulated by the speed of
the plunger, and not as usual by the length of its stroke. This is effected through
the disc b and friction wheel c, the latter being adjustable across the face of the
former by means of the hand screw d. The friction wheel c slides over the spindle
c, which it drives through a sunk key. Upon the end of the spindle is an eccentric
f which drives the crank g, which is formed upon the end of the spindle upon
which the rocker A turns. From the face of this rocker the coal is pushed through
the channel h over the edge h¹, shewn in dotted lines in Figure 42. This edge
is split into a number (six in the Figure) of separate lips, the outer edges of
which are immediately above the edge of the fan. These lips are attached to the
fan box cover by means of hinges j, Figures 40, 42, and 47. These lips may be
formed, as in Figure 47, with a screw, so that they can be adjusted by hand, the
coal being retarded in its passage over the edge h¹ in proportion to the elevation of
the lips.
In Figures 40 and 42 a method of automatic adjustment is shewn controlled by
the speed-varying gear previously described, so that the stream of coal falling upon
the face may be narrower when the latter is moving at a high speed, and wider
when it is moving more slowly. Each lip is attached by its bottom centre to a
connecting rod k, k, Figures 40 and 42, which is moved by the crank 1, the latter
being driven by the rod m, m, which is connected with the speed-varying gear, so
that it closes the side lips as the speed of the fan rises, allowing the coal to fall
only in a narrow spray. The directions of discharge of coal from the fan are shewn
approximately by the dotted lines upon the grate surface.
To reduce the amount of dust carried off by the draught into the flues of the
furnace, it is sometimes found useful to slightly damp the coal, as herein-after
described. When this is done, the adhesion of the finer particles together into little
masses is greatly assisted by some pressure being exerted upon them. This may be
done by means of a plate hinged in the neck of the aperture (sec A, Figure 43),
and, when closed, preventing all egress of the coal. This plate has an arm and
counterweight a upon its hinge, so placed as always to press it downwards.
To feed coal upon the fans the ram b must press the coal against this plate with
sufficient force to lift the counterweight, and in so doing compresses the dust as
required.
In cases where the passage of the dust out of the flues and stack is found a nuisance,
as in glassworks, passenger steamers, &c., it may be trapped by means of its greater
momentum than the gases in which it moves. This may be done by making the
whole of the products of combustion turn sharply round a corner when the heavier
particles will, in consequence of their superior centrifugal force, be projected to the
outside of the curve, where they may be easily entrapped under a shelter behind
which the draught has no access, where they may freely deposit themselves through

page_text: still air. A series of such traps are shewn in plan in Figure 44, the arrow shewing
the direction of the draught. This dust will also deposit itself by means of its
greater specific gravity than that of the gas in which it is suspended, if it is allowed
to pass together with the rest of the products of combustion in a broad shallow
stream along a wide deep flue, Figure 46, all draught in the bottom of which is
prevented by means of a series of transverse partitions a. As the shallow stream
of gas moves along the dust will readily settle down behind the partitions through
the still air below into a position in which it can do no harm, and from which it
can be removed at suitable intervals by means of the doors b, b.
Figure 45 shews another arrangement for trapping, which will be understood
without further explanation. But the most effectual way of dealing with this dust
is to remove it from the coal before the latter is thrown into the furnace. This
may be done by causing the main stream of coal being brought forward to the
machines by any of the means herein-after described, to fall freely through the air
for a short distance. If past this falling stream a slight current of air is driven
either by steam jets or any more convenient means, that portion of the small coal
which is so finely divided as to be powerfully influenced by draught will be
separated from the rest, and may be received into a suitable chamber at one side
of the stream of coal from which this dust has been extracted. If this dust is then
treated with petroleum, tar, or other compound, at the same time glutinous and
inflammable, and afterwards first mixed and then compressed, it can be again
discharged into the travelling stream of coal, and carried on with it to the furnaces
in a form more convenient for the purpose, and also more economical than that of
finely divided dust. This object may be effected by means of placing a mixing
worm at the bottom of the chamber in which the dust is received. This worm
may terminate in a forcing end, of taper form or otherwise, beyond which a short
spout or nozzle of small diameter may conduct the material back to the coal con-.
veying gear.
If the sides of the receptacle in which the dust is received be made to converge
at a suitable angle towards the mixing portion of this worm, and petroleum or other
more suitable material be allowed to fall in small quantities upon it, the whole will
be effectually mixed together, and subsequently forced by the end of the worm
through the small nozzle, within which means may be employed to dry it, if
required, on to the travelling gear where it will break off in convenient sized pieces
and be conducted together with the rest of the coal onwards to the various
machines. It may however be in some instances convenient to steam users to
simply extract this dust by the method described, and collect it for sale or other
convenient purpose without immediately utilizing it in the machines, as described.
Figures 70, 71, and 72 shew a method of extracting the dust from the coal before
the latter is put upon the fire. The band a, carrying forward its load of coal, dis-
charges it over the pulley A into the spout b, b, through which it falls on to the
band at that position marked a³. The band is conducted to a² over the pulley A
and under the pulley B. As the coal falls through the spout bits particles are
separated, so that they can be acted upon individually by a draught to cause a still
greater separation. Through the aid of the jets c, c, c, c, the required draught is
caused, which is regulated so as to be sufficient to carry the finer particles over the
edge d into the box e, down the sides of which they will settle towards the worm f
This worm, driven by worm and wheel gear, as shewn, may have some of its threads
so formed as to mix the dust if required with any liquid matter that may be
arranged to fall upon it from above, and drying, should that also be needed, may
be effected by passing steam round the nozzle g, through which the compressed
dust is forced on to the band a² and carried forward together with the rest of the
coal. The worm may have a hearing, if desired, or have its thread thickened at the
end, so as to take a bearing against the sides of the nozzle. The band a² may have
substituted for it a worm or a split pipe (such as that herein-after described) as
desired, and the end of the band a' may be returned under the pulley A, these

page_text: alternative arrangements being similarly intended to carry out the principle of
extracting the dust before the coal is put upon the fire.
When a number of furnaces are in a line, or nearly so, with one another I find it
advantageous to employ a system of constant supply of coal to the machines, direct
from the coal wagon or the bunker in which the coal is kept, so as to reduce the
amount of labor required for working the fires by superseding all hand working of
the fuel before it is fed into the furnace. I am also able by the same means to avoid the
necessity of keeping a reserve supply of coal above each separate machine, thus at
once getting rid of the usual cumbrous and unsightly hopper.
I may effect
this object completely and satisfactorily in several ways. In the first of these
I use a worm which turns upon a horizontal axis in line, or nearly so, with the
machine.
Figures 13 to 22 shew an arrangement and details of such a worm; A, Figures
13 and 14, is a bunker specially adapted to it. From the sides of the worm a false
bottom a slopes upwards at such an angle as will admit of the coals easily sliding
down it to the worm. b, b, is a roof above, which both serves to prevent too great
a weight of coal pressing at once upon the worm, and renders the latter and its
bearing c, c, easily accessible.
A considerable weight of coal always lies upon the bottom a, a; and to prevent too
great a length of this pressing upon the worm the stop boards d can be fixed in any
desired position.
The worm shewn has a smaller pitch within the bunker than without it, so as to
prevent its bringing forward an overload of coal to the part of the worm above the
machines.
The shape of the worm case is shewn at Figure 18, and its hangers and
details, Figures 21 and 22; a, a, a, is a hanger so formed as to be the least possible
obstruction to the coal, the diameter of the bearing being the same as that of the
base of the worm. b, b, is a shaft upon which the cast-iron worm lengths are
threaded. Immediately in front of each bearing a collar is turned upon the shaft,
and then cut out into the form of a quadrant clutch, which fits into a corresponding
clutch in the casting; each preceding casting drives the succeeding one between this
and the next bearing in a similar manner, the one being clutched on to the other.
A convenient mode of coupling one shaft to the other is shewn at c, Figure 21.
Here the shafts are "scarfed" into one another, and the last worm length, preceding
the bearing, strengthened and made a driving fit, and driven over the scarf joint,
taking the place of the ring commonly used. Thus no obstruction is placed in the
way of the free passage of the coal, and when the bearing is removed, room
is given to draw back the worm length and uncouple the shafts.
Modes of joining the worm to the machine are shewn in Figures 14, 15, 16, 17,
23, 24, 35, 36, 38, and 39, and a view of its junction to the machines, Figures 1 to 6,
is shewn in a small scale view, Figure 50.
In Figure 14 the last machine is so arranged as to take the whole remaining supply,
the speed being regulated by the man adjusting the belt over the cones e, f, by
striking gear of usual pattern.
To prevent any pressure in the case, should too much coal come on, a relief vent g
is shewn, which I have found useful also to inform the man when there is an
excess of speed. Any little excess simply falls upon the. bottom, but the man
by practice is able to prevent this being more than a very small quantity.
The use of a small hopper for taking the excess is shewn in Figure 51, where the
worm a is tapered, and discharges its coal around its axis. Any excess that is
coming on, and not being withdrawn by the ram which works in the recess b, is
forced upwards into the hopper c. When it is desired to govern the worm by the
pressure of the coal, I sometimes use an arrangement shewn in Figures 52 and 53.
Here the worm is tapered and works over a recess like b, Figure 51, but any excess
of coal presses against a bed c, Figure 53, which is kept down by a counterweight
At the back an extension of the lever upon which the counterweight is fixed
carries an eye, which is connected by levers or otherwise with the striking gear and
e, e.

page_text: belt forks guiding the belt upon cones e, f, Figure 14, so that as the lid crises the cone
driving the worm gear runs more slowly. The lid c may be made to open longi-
tudinally if desired.
Figures 48 and 49 shew a hopper of large size from which the supply can be with-
drawn by the worm.
Here a set of shutters, any of which may be opened at a
time, are used so that they may protect parts of the worm from the weight of
coal pressing upon it; they are hinged at their centres and can be turned from the
outside.
Figures 23, 24, 35, and 36, shew the method of joining a high level worm to the
fan box casting, and so on to enable machines that are not level with one another, or
otherwise out of line, to be supplied.
The arrangement of horizontal supply may be usefully applied to feeding machines
direct from the bunkers on board ship, and is especially convenient, as, in con-
sequence of the absence of hoppers in most cases, all obstruction to opening the
smoke box doors (A, Figure 54) is avoided, and the whole system of furnace feeding
rendered much more compact and convenient. In these cases the worm may be
fixed horizontally immediately above the rams of the machine (see a, Figure 54) as
before described, and continued onwards into each bunker, the ends being tapered off
(a', a¹), so as to compel them both to feed the body of the worm lightly, and to
discharge the excess of coal around their axes easily. The driving gear of this
worm b, Figures 54 and 55, may be conveniently arranged upon a continuation of
its axis in a recess formed within one of the bunkers, a tunnel or man-hole under-
neath the end of the worm giving free access to it. The gear by which it is driven
may be made reversible, so that the worm will draw its supply from either bunker,
as desired, or alternately from each.
The driving gear for the worm, shewn in Figures 54 and 55, is both adjustable
in speed and reversible in direction. Upon the end of the crank shaft a friction
disc is shewn, across the face of which the friction wheel impinging upon it is
moved by suitable hand adjustment gear. This friction wheel through a worm and
worm wheel drives the feeding worm, the direction of which governed by the
friction wheel being upon one side or the other of the friction disc, so as to get a
right or left hand motion, and the speed is regulated by its nearness to the centre of
this disc. The man-holes or tunnels enable the bearings and driving gear to be
easily got at.
Over the worm in each bunker, and at some distance above it, is fixed an adjust-
able sheltering plate c, Figures 54 and 55, of such width that the "angles of
repose" at which the coal in the bunker will, from either of its edges, underlap this
plate, will allow the coal to just lightly lie around and within the thread of the
end of the worm d', in such a manner that the latter, without being in any way
overweighted with coal lying above it, may yet be able to draw a continuous and
even supply across the machine. Any excess of the supply being brought on by
the worm to the machines at any time will be carried on by the former into the
opposite bunker, where that taper end of the worm will freely discharge it around
and above its axis into the space left underneath the sheltering plate, previously
described, which will be of triangular section, base upwards, bounded upon the top
by the plate, and upon either side by the bunker, coal lying at its angles of repose
underneath it. As in this respect each end of the worm is similarly arranged, it
will work equally well in one direction as in the other, and may be thus worked so
as to withdraw equal quantities from each bunker; or, if desired, by working it
longer in one direction than in the other, it may be made to withdraw a larger
quantity from either bunker as required.
It is sometimes desirable, for the sake of compactness and lightness, to employ
an arrangement for supply of coal to these machines which will go into a smaller
compass than the worm, which latter, to be efficient, must be itself of considerable
diameter and weight, enclosed within a still more bulky case, and altogether forms
n considerable obstruction in front of a boiler, besides adding weight to the load on
the boiler front or furnace frame. This may be done by means of a pipe a, a¹,

page_text: Figures 50 to 60, split longitudinally down the centre in such a manner that the
two halves are free to reciprocate independently of one another, the bottom half
travelling in a forward direction while the top half is travelling backwards.
These two separate halves may be reciprocated in alternate and reverse directions
by means of a lever b, Figure 56, the centre or fulcrum of which is carried by a solid
pipe c, Figures 56 and 58, which turns with the split pipe, but within which the
latter is free to reciprocate. The connecting rods d, d, attach the top end of this
lever to the top half of the pipe, which is here strengthened and turned in a lathe,
as required, and the bottom end of the lever to the bottom half of the pipe, and by
moving the lever backwards and forwards upon its centro the necessary reverse
reciprocations of the two halves of pipe are effected. When this pipe contains coal,
as the friction between the coal and the bottom half of the pipe is greater than it is
between the coal and the top half, the former will always be carried in that direction
in which the bottom half is moving. When the lever b has reached the end of its
stroke, carrying together with it the bottom half of the pipe and the coal that it
contains in the direction in which it is required, and the top half of the pipe back-
ward in the opposite direction, this whole arrangement of the pipe lever and con-
nections is by suitable gear e, f, Figures 56 and 58 inverted, so that what was the
top half and is in its backward position becomes the bottom half, and consequently
that on which the load of coal rests, and what was the bottom half, becomes the top
half, and is free to move backwards without carrying the coal backward with it.
Then the return stroke of the lever and halves of pipe is effected, the coal being
moved onwards by similar means, and in the same direction as before.
The driving of this mechanism may be effected by means of a reciprocating barg,
and clutches h, h!, so arranged that in its forward stroke it takes hold upon the
lever and gives it and the pipe the required reciprocal motion, while in its back-
ward or return stroke it gives motion to the bevel spur gear e and f, which inverts
the pipe and lever gear, as described. The end of this pipe within the bunker will,
by the simple alternate motion of its halves, scoop out the coal and carry it onwards
as required. The junction j (Figures 56 and 60) of the pipe with each of the
machines, excepting the last one, is effected by making a sufficiently large hole in
the bottom of each half pipe l, l, which at the back end of its stroke is immediately
over the ram of the machine it is feeding.
The end machine may be fitted in any of the three ways described, as used in the
case of the worm feed, but when using the first or third of those methods of feeding
it the end of the pipe is thickened and formed into a forcing ram m, m', Figure 57,
so as to compel the coal to enter as required. The longitudinal joint of this pipe
inay be formed to prevent leakage of coal by lapping each side of cach half pipe
well round the corresponding side of the other half (see Figure 59) in such a direction
that the inside edge never faces the direction of the pipes' turning motion when
being inverted.
A third method of supply and one which, measured vertically, goes into a still
smaller compass, consists of a continuous band travelling over pulleys, and carrying
the coal across the machines upon its upper surface in a manner similar to that used
in corn mills and warehouses for grain or flour. Such an arrangement is shewn in
Figure 61, and the details in Figures 30, 31, and 32. In this manner the band is
made to bring a continuous stream of coal from the wagon or bunker over the top
of each fan box, and immediately in front of the port through which the fuel is
forced by the ram on to the fans. In this case the coal is withdrawn from the
bunker A by means of an elevator, which through a guide spout discharges it on to
the band a, Figure 61, and f, Figures 30, 31, and 32. Each of the machines pre-
'viously described withdraws its supply in any desired quantity from the band
while the latter is in motion by means of the scraper g, which is adjustable across
the surface of the band. Any remainder carried forward by the band, after the last
machine has been supplied, is discharged over a pulley into the bent spout b, Figure
61, by which it is conducted on to the return half of the belt a¹, a', by which it is
carried back again to the elevator, being discharged among the bunker coal.

page_text: Figures 62 and 63 shew another method of withdrawing coal from such a belt.
Here the belt a, a, travels over the pulleys b, b, immediately in front of the edge c,
over which the coal falls upon the fans d. The band is driven with an intermittent
motion, and is acted upon by the ram or scraper f only when stationary. When
the scraper f begins its traverse it releases the lever e, e, which by the weight e¹
presses the inner edge of the belt firmly against the knife edge shewn; thus no coal
can be scattered by the action of the scraper towards the extreme edge of the belt.
The scraper fis made adjustable in height so as to enable the attendant to increase
or diminish the feed, and if found necessary the adjustment may be effected by a
screw and hand wheel. Any pieces of coal that may remain upon the edge c are
pushed back on to the belt in the return stroke of the scraper by means of the inner
edge f, which also is useful to prevent the ingress of cold air. The scraper is
actuated from the rocking shaft h through a pair of bent levers j,j, and the fans are
driven in the usual manner.
The alternate motion of the band and scrapers may be obtained by gear, such as
that shewn in Figures 64 and 65. Here a is the shaft driving the machines, which
through a worm turns the worm wheel b. This drives two cranks c and d, carrying
ratchet pauls e and f. These cranks are at the same side of the centre of the
worm wheel b, b, and in their up stroke they give the belt g motion through the
ratchet and pulley h, while in their down stroke they give the scrapers motion
through the bevel wheel and pinion j and k, and disc crank and lever m and n,
which communicate with them by means of the rocking shaft o (h, Figures 62
and 63, and f, Figures 66 and 67).
Figures 66 and 67 shew another arrangement of machine possessing some advan-
tages. Here the amount of coal fed by the ram on to the fans does not in any way
depend upon the scraper, but is governed by the rocking ram b, which is driven by
suitable lever gear through the crank b¹. The neck of the box above is always
kept full up to the edge c by means of the scraper a, which is formed to bring from
the band a greater quantity than is required, the balance of which is returned to it
upon the return stroke by the scraper a¹. These scrapers are actuated by the con-
necting rod and lever d and e from the rocking shaft f, placed in this case for con-
venience behind the fan box. The fans are driven as before. The weighted clamp g
holds the belt firmly while the scraper passes over it, as before described. The
scrapers f, Figure 63, and a, Figure 67, are each of them lifted automatically by a
spring in the side of the casing so as to clear the coal in their return stroke.
scraper a', Figure 67, is made in its backward traverse to rather overstep the knife
edge so as to push the coal well back on to the belt, returning to the position shewn
in the Figure at the completion of its stroke.
The
Should all the machines that require to be fed from the one stream of coal not be
in line with one another the band may either be made to discharge its coal upon
another band, taking the required direction across part of the machines, or by means
of a system of pulleys common in corn warehouses, the original band may be first
bent downwards and backwards so as to discharge its load of coal into a small guide
or shoot, and then by means of other pulleys given the required new direction, then
passing immediately under the shoot or spout before named, again receive its load of
coal, and carry it straight onward to the succeeding machines. This method
of supplying the machines with fuel has the advantage of never breaking the
coal as the worm is found to do in some degree, especially where great lengths
are used.
The band may be also made to withdraw its supply from any distance and from
any position, and will carry its load up or down an incline of from 20 to 28 degrees.
It may be loaded direct from the bunker either by simply passing under an open
coal spout in the manner adopted for carrying flour; or, to avoid excessive wear and
tear, it may be gradually fed by plunger, or rollers, or crusher where it is convenient
to use such apparatus. It may be either wholly or partly enclosed within a case, so
as to prevent air being sucked in through the coal passages in the machines; or
where this is undesirable a light hanging shutter or screen may be placed on each

page_text: side of the plunger in such a manner that while not interfering with the coal upon
the band, it yet practically closes the passage against air. Thus my principle is to
withdraw the supply for furnaces not from local reserves, as that contained in a
hopper above them, but from a constantly passing stream of coal brought forward
from the main bunker crushing apparatus or coal truck by any convenient
mechanical means,
three of which have been already described, and I thus avoid
much labor that would otherwise be expended in handling the coal, and remove a
source of dirt and annoyance from the stoke hole.
Figure 73 shews a band bent into a new direction, for the purpose above
described. A is the band, taking the first direction, from which it falls over the
pulley B, the coal being discharged into the shoot D, through which it falls on to
the part of the band A², taking a new direction; C is a pulley facing the new
direction of the band's motion, and the twisting of the band is effected between B
and C, as shewn.
Figure 74 is a longitudinal section of a partially enclosed band. A is the band;
B, the enclosure above a machine; C, the opening through which the coal is thrust
by the scraper; d, d, are hanging shutters to exclude air from entering with the
band through the pipe C, C¹, to the furnace.
Where it is desirable to use large coal, I crush it to the required size at the source
of its supply before it is brought forward by the worm pipe or travelling band, and for
this purpose I prefer to use a crusher working somewhat upon the principle of what
is known as Blake's stone crusher; but as it is an object to prevent the formation of
dust, I preferably make both the crushing jaws of open structure, and not of solid
plate, so that when in the upper part of the jaws pieces of coal are broken up small
enough for my purpose, they may be at once free to disengage themselves from the
crusher either through the aperture between these jaws at the bottom in the usual
manner, or through the structure of the jaws themselves. This may be done by
forming each jaw of a strong framework, within which can be placed, at suitable
distances apart, vertical knives of steel or other hard metal, which, if broken or
worn, may be easily replaced.
The crushing gear may be easily driven by the saine gear which actuates the
coal conveying gear and furnace feeding machines. Arrangements of this kind are
particularly applicable to steamships, which, when coaling at foreign stations, can
only obtain large coal.
Figures 66 and 67 shew a bunker and arrangements useful for supplying a
number of furnaces where large coal is employed. Here a bunker A, A, similar in
principle and construction to that shewn in Figures 13 and 14, is used. From
under the sides of the roof B the coal slides down the sloping bottom to the large
aperture C, which extends the whole length of the bunker. Through C the coal
falls and comes to rest upon the plate d, where it will remain if undisturbed. The
further impulse required to project it over the edge of this plate, so that it may fall
upon the band e, is given by the rocker D, which is driven by a crank and bevel
gear from the end band pulley, as shewn. The plate ƒ prevents the large lumps
of coal from falling towards the edge of the band. Access may be had to this
bunker both above and below the plate d by the door, which, although wide enough
for a man to get through, will not admit of an overflow of the coal. The band e, e,
carries the coal over the pulley h, from which it falls upon the screen j, which
separates the small pieces from the large, the former dropping through the screen at
once to the elevator 1, and the latter passing down the screen to the crusher K,
through which they fall to the elevator, being in the act again mixed with the
portion that passed through the screen. The elevator discharges the whole of the
coal over the pulley into the worm case m, through which it is conducted to
the machines feeding the fires.
Any of the other methods of feeding, herein-before described, may replace the
worm m, and if desired the screen and crusher j and K may be made in one, as
previously described. The crusher K is shewn for convenience driven through a bell
crank from the eccentric n.

page_text: And having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I claim as my "Improve
ments in Apparatus or Means for Supplying Furnaces with Fuel and in Furnace
Flues,"
First. The various arrangements of mechanical stokers or apparatus for sup-
plying furnaces with fuel, as herein-before described, and represented in the
accompanying Drawings.
Second. The combination of friction and spur gear for driving the fans of
mechanical stokers, substantially as herein-before described, and represented in
Figure 4.
Third. The mode or means of attaching the fan to the spindle by screwing it
down with a nut upon a collar, as shewn at j, Figure 1, or a cone, as shewn at h,
Figure 4, and lubricating the bottom bearing through the fan spindle, substantially
as described.
Fourth. The fitting of loose rings round the fans, substantially as herein-before
described, and represented in Figure 4, for the purpose explained.
Fifth. The driving of a rocking ram through the intermediation of a crank
(h', Figures 18 and 19) and lever gear, which is adjustable either in length of stroke
or speed, substantially as herein-before described.
Sixth. The particular arrangement of adjustable lever, shewn in Figures 18, 19,
and 20, and herein-before described.
Seventh. Driving the fans (whether horizontal or vertical) of mechanical
stokers at a constantly or periodically varying speed, as as to feed first at the front
and then at the back of the grate, substantially as herein-before described.
Eighth. The mode or means of constantly or periodically varying the speed of the
fans by varying the speed of the engine, such variation of the engine speed being
caused by giving through suitable gear a motion to the governor, varying relatively
to that of the crank shaft, substantially as herein-before described, and represented
in Figure 28 and in Figures 26 and 27.
Ninth. The mode or means of constantly or periodically varying the speed of the
fans by traversing a belt over a pair of cones or traversing friction wheels across the
face or faces of friction discs, or vice versa, substantially as herein-before described,
and represented in Figure 25 and in Figure 29.
Tenth. The mode or means of varying the amplitude of the coal spray, driven
outward by the fans, by varying the width of the stream of coal falling on the
fans, substantially as herein-before described, and represented in Figures 30, 31,
and 32.
Eleventh. The adjustable guide plates, herein-before described with reference to
Figures 30, 31, and 32, and adjustable lips, herein-before described with reference
to Figures 40, 41, and 42, for the purpose explained.
Twelfth. The mode or means of varying the amplitude of the coal spray by
adjusting with shutters the position of the stream of coal falling on to the fans,
substantially as herein-before described, and represented in Figures 35, 36, and 37.
Thirteenth. The connecting of the speed varying gear with the guide plates (Figures
30, 31, and 32), or with the lips (Figures 40, 41, and 42), or with the shutters
(Figures 35, 36, and 37), so that they may be driven by the same mechanism, and
that the adjustment of the said plates, or lips, or shutters may be thereby produced
in synchronism with the varying speed of the fan, substantially as herein-before
described, and represented in the Figures.
Fourteenth. The mode or means of varying the amplitude of the coal spray in
synchronism with the varying speed of the fan by employing fan beaters capable of
automatic adjustment in accordance with the speed of the fan, substantially as
herein-before described, and represented in Figures 33 and 34.
Fifteenth. The supplying of horizontal fans with coal at or very near their edges
only, substantially as and for the purpose herein-before described with reference to
Figures 40 to 42.
Sixteenth. Providing mechanical stokers or fuel-feeding -apparatus with means

page_text: of damping and afterwards slightly compressing the coal for the purpose of
preventing dust, substantially as herein-before described, and represented in
Figure 43.
Seventeenth. Providing mechanical stokers or fuel-feeding apparatus with
means of separating the dust from the rest of the coal before firing, and of
then damping and compressing such dust, and feeding the same to the furnace,
substantially as herein-before described, and represented in Figures 70 to 72.
Eighteenth. Constructing furnace flues with traps, substantially as herein-before
described, and represented in Figures 44 to 46 for preventing coal dust being carried
"out of the chimney.
Nineteenth. The employment, for supplying a number or series of furnace-feeding
machines, of a worm arranged and acting substantially as herein-before described,
and represented in Figures 13 to 22.
Twentieth. The combination with a worm for supplying a number or series of
furnace-feeding machines of rams, each working within a corresponding recess in
the bottom of the worm case, substantially as herein-before described, and repre-
sented in Figures 14 to 20, 23, 24, 38, 39, and 48 to 54.
Twenty-first. The combination with a worm for withdrawing coal from a large
receptacle of a roof, substantially as herein-before described, and represented in
Figures 13 and 14, and Figures 54 and 55, for protecting the worm from the weight
of superincumbent coal.
Twenty-second. The combination with a worm for withdrawing coal from a large
receptacle of shutters, substantially as herein-before described, and represented in
Figures 48 and 49, for protecting the worm from the weight of superincumbent
coal.
Twenty-third. The employment of stop boards, as shewn at d, Figure 13, and
herein-before described, for further limiting the supply of coal to a worm which
withdraws coal from a large receptacle.
Twenty-fourth. Constructing a worm for supplying furnace-feeding machines
with its thread sloping backward at the parts immediately over the aperture leading
into each recess containing a ram, so as to assist the coal into such recess, as herein-
before described, and represented in Figure 50.
Twenty-fifth. Constructing a worm for supplying furnace-feeding machines with
its end tapered, so that it may gradually let go its hold upon the coal, and so set up
or assist in setting up a pressure of coal at right angles to the worm's axis, and thus
enable the coal either to lift itself into a hopper above the worm case, or to lift a
lid attached to gear governing the worm's speed, substantially as herein-before
described, and represented in Figures 51 to 53.
Twenty-sixth. The construction of a relief vent for the surplus coal, either
upwards into a hopper, as herein-before described, and shown in Figure 51, or
downwards on to the ground, as at g, Figure 14, for the purpose of preventing the
choking of the worm case near the last of a series of machines supplied by the
worm.
Twenty-seventh. The fitting of a self-adjusting valve or lid, substantially as
herein-before described, and represented in Figures 52 and 53, connected with the
speed gear for automatically governing the speed of a fuel-feeding worm by means
of the pressure at its end set up as explained.
Twenty-eighth. The construction and employment, for conveying coal to fan
machines, of a split pipe, arranged and acting substantially as herein-before
described, and represented in Figures 56 to 60.
Twenty-ninth. The employment, for supplying furnace-feeding machines, of a
travelling band, from which the coal is withdrawn to each of the machines by
means of a scraper, substantially as herein-before described, and represented in
Figures 30 to 32, and Figures 61 to 67.
Thirtieth. The employment of fixed scrapers for removing coal from a travelling
band, substantially as herein-before described, and represented in Figures 30 to 32.
Thirty-first. The employment of scrapers moving across the face of the band

page_text: which conveys the coal, the amount of coal withdrawn therefrom being governed
either by the depth of the scraper or the length of its traverse, substantially as
herein-before described, and represented in Figures 62 and 63.
Thirty-second. The employment of scrapers so arranged as to keep the boxes, in
which the corresponding feeding rams act, always full, the amount of the feed being.
governed by the rams, substantially as herein-before described, and represented in
Figures 66 and 67.
Thirty-third. The employment of driving gear so arranged as to give an alternate
motion to the band and scrapers, as herein-before described, and represented in
Figures 64 and 65, and clamping the band to the furnace feeder during its interval
of rest, as herein-before described, and represented in Figures 63 and 67.
Thirty-fourth. The arrangement by which any surplus coal left after the machines
have all been supplied by a travelling band is returned to the main reserve either
by the returning part of the same band, or by a separate band, substantially as
herein-before described, and represented in Figure 61.
Thirty-fifth. The arrangement by which in a machine for feeding furnaces a
feeding band is given a new direction, as herein-before described, and represented
in Figure 73.
Thirty-sixth. The employment of hanging shutters for preventing the ingress of
air, substantially as herein-before described, and represented in Figure 74.
Thirty-seventh. The combination with a band for carrying coal from a bunker or
other source of supply, of a ram or plunger for feeding the coal to the band,
substantially as herein-before described, and represented in Figures 68 and 69.
Thirty-eighth. The construction and employment of an apparatus for crushing
the entire supply of coal for furnaces between the bunker and the fires, so as to
screen out the small and avoid its being further broken, substantially as herein-
before described, and represented in Figure 69.
In witness whereof, I, the said Joseph John Butcher, have hereunto set my
hand and seal, this Twenty-third day of March, One thousand eight hundred
and seventy-eight.
JOSEPH J. BUTCHER. (L.9.)