IMPROVEMENTS IN MECHANICAL STOKING APPARATUS FOR STEAM DUILER AND OTHER FURNACES.
Year: 1875

page_text: LETTERS PATENT to James Donald, of the Firm of George Miller and
Company, of Glasgow, in the County of Lanark, North Britain,
Manufacturing Chemists, for the Invention of "IMPROVEMENTS IN
MECHANICAL STOKING APPARATUS FOR STEAM DUILER AND OTHER FURNACES.
PROVISIONAL SPECIFICATION left by the said James Donald at the
Office of the Commissioners of Patents, with his Petition, on the
13th February 1875.
I, JAMES DONALD, of the Firm of George Miller and Company, of
Glasgow, in the County of Lanark, North Britain, Manufacturing
Chemists, do hereby declare the nature of the said Invention for “Im-
PROVEMENTS IN MECHANICAL STOKING APPARATUS FOR STEAM BOILER AND OTHER
FURNACES," to be as follows, that is to say :-
This Invention has for its object by means of improved mechanical
stoking apparatus to secure a practically uniform condition of the fuel
in a steam boiler or other furnace, so that the best proportion of air may

page_text: be easily ascertained, and its admission be rendered constant, with the
view of avoiding smoke and obtaining the best duty from the fuel.
In carrying out the Invention a hopper is fitted at the mouth of the
furnace to primarily receive the fuel, which should be in the form of
coal dross, or in small pieces. The bottom of the hopper is fitted with a
sliding door, which when open allows the fuel to fall on a horizontal plate
situated at about the intended level of the fuel in the furnace and with a
space between it and the level of the fire-bars, which is provided with a
door, and through which a poker can be introduced for loosening clinkers
when ordinary fire-bars are used. The quantity of fuel which has dropped
upon the horizontal plate is at intervals pushed forward into the furnace
by a plate or pusher moved by a horizontal rod, which forms or is attached
to the piston rod of a long hydraulic cylinder of small diameter situated
outside of the furnace.
The pusher is by preference moved inwards nearly to the inner end of
the furnace so as to uniformly spread. the fuel and level its upper surface,
and the plate of the pusher is hinged at or near its upper edge so
as on returning outwards to pass easily over any obstructing pieces of
coal.
On the pusher commencing its inward movement it acts on tumbler
catches fitted to the hopper slide, so as to move this slide inwards and
close the hopper outlet, the catches relieving themselves by encountering
stops when the slide has moved far enough. Then on the return out-
wards of the pusher it opens the hopper slide again as it is about com-
pleting its stroke, so that a fresh supply of fuel may descend to be.acted
on by the pusher when next moving inwards.
The hydraulic cylinder is by preference fitted with a four-way cock,
which is reversed by a tumbling lever actuated by water. This tumbling
lever is weighted on one side, and at the other side carries a box, into
which a constant small stream of water is led. The water accumulates
until its weight overcomes the counterweight, and then tilting the lever
makes it move the cock or valve. The lever is held by a spring detent
in its tilted position until this detent is acted on by the piston on reaching
the end of its inward stroke, but the water having by that time run out
of the box the lever returns to its other position, and in doing so reverses
the cock or valve so as to bring about the return or outward stroke of
the piston. The length of interval between each action of the apparatus

page_text: depends on the rate at which the water is allowed to flow into the box of
the tumbling lever, and can be easily regulated by a stop-cock on the
supply pipe.
The hydraulic cylinder is by preference mounted on trunnions on a
carriage, admitting of its being quickly moved away from the furnace
mouth when required, and when in use it is connected to the furnace
mouth by rods arranged so that they can be easily disconnected.
As herein-before indicated ordinary fire-bars can be used with the appa-
ratus. It is, however, preferred to employ bars and arrangements
connected therewith of the improved kind herein-after described.
The improved bars consist of main parts disposed transversely in the
furnace and formed with trunnions or knife edges at their ends to rest on
lateral longitudinal bearers so that the bars can rock. Each bar is formed
with short pieces projecting from its sides, and therefore lying longi-
tudinally in the furnace, and such projecting parts of one bar enter in
between the similarly projecting parts of the adjacent bars. Longi-
tudinal rods extending under the bars are jointed to snugs projecting
downwards from their main parts, and such rods being moved longi-
tudinally cause the bars to rock. The rocking will make the longitudinal
parts work past each other, so as to take in and carry down the ashes
and dust from the fuel, and so as to remove clinkers, and will thus clean
the fire, and it may be effected at intervals by hand or by means of
hydraulic apparatus.like that herein-before described for working the
fuel-supplying apparatus, the use of the hydraulic apparatus for the
purpose being preferred, as regular action is thereby secured and risk of
neglect by the fireman avoided.
0
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Donald in the Great Seal Patent Office
on the 12th August 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
DONALD, of the Firm of George Miller and Company, of Glasgow, in
the County of Lanark, North Britain, Manufacturing Chemists, send
greeting.

page_text: WHEREAS Her most Excellent Majesty. Queen Victoria, by Her
Letters Patent, bearing date the Thirteenth day of February, in the year of
our Lord One thousand eight hundred and seventy-five, in. the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said James Donald, Her special licence that
I, the said James Donald, my executors, administrators, and assigns,
or such others as I, the said James Donald, my executors, admini-
strators, and assigns, should at any time agree with, and no others, from
time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN MECHANICAL
STOKING APPARATUS FOR STEAM BOILER AND OTHER FURNACES," upon the con-
dition (amongst others) that I, the said James Donald, my executors
or administrators, by an instrument in writing, under my, or their, or
one of their hands and seals, should particularly describe and ascer-
tain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the
Great Seal Patent Office within six calendar months next and imme.
diately after the date of the said Letters Patent.
事
NOW KNOW YE, that I, the said James Donald, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement in writing, reference being had to the accompanying
Drawings, that is to say :—
My said Invention has for its object by means of improved mechanical
stoking apparatus to secure a practically uniform condition of the fuel
in a steam boiler or other furnace, so that the best proportion of air
may be easily ascertained, and its admission be rendered constant, with
the view of avoiding smoke and of obtaining the best duty from the
fuel.
My improved apparatus is so contrived that at regular intervals equal
small quantities of fresh fuel are evenly spread over the surface of the
fire, and this is effected by means of a pusher or kind of rake, which
moving over the surface of the fire at a fixed level pushes the fresh fuel
in front, spreading it and levelling the fire.
And in order that my said Invention and the manner of performing
the same may be properly understood I hereunto append a Sheet of

page_text: explanatory Drawings, to be herein-after referred to, and representing a
practically successful modification of my improved mechanical stoking
apparatus. In these Drawings the same reference numerals are used to
mark the same or like parts wherever they are repeated.
Figure 1 of the Drawings is a longitudinal vertical section of the
entire apparatus, and of a portion of an internally fired horizontal
cylindrical boiler, to which it is fitted; and Figure 2 is a transverso
vertical section of the part of the apparatus occupying the front end of
the furnace flue.
A hopper 1 is fitted over against the mouth of the furnace flue 2 to
primarily receive the fuel, which should be in the form of coal dross or
in small pieces. The hopper is at its bottom formed with an opening 3,
which is fitted with a sliding door 4, consisting of a horizontal plate
supported on guides formed in the mouth-piece casting 6. When this
door 4 is opened by being moved outwards, as herein-after explained, a
quantity of the fuel falls down on a horizontal plate 7 fitting within the
lower part of the mouth-piece 6, and situated at about the intended level
of the fire, that is, of the fuel in the furnace space 8. At its inner end
the plate 7 has attached to it a nearly vertical plate 9, reaching down and
hinged to the front bearer 10 of the furnace bars 11, whilst holes are
formed in the plate 9 for the admission of air. The quantity of fuel
which has dropped upon the horizontal plate 7 is at intervals pushed
forward into the furnace 8 by a plate, rake, or pusher 12, moved by a
horizontal rod 13, which forms the piston rod of a long hydraulic
cylinder 14 of small diameter situated outside of the furnace.
The pusher 12 is by preference moved inwards nearly to the inner end
of the furnace so as to uniformly spread the fuel and level the upper
surface of the fire, and the plate of the pusher is hinged at its upper
edge to a cross bar fixed on the end of the rod 13 so as on returning out-
wards to pass easily over any obstructing pieces of coal.
On the pusher 12 commencing its inward movement it encounters a
pair of tumbler catches 15 jointed to the sliding door 4, and moves this
door inwards and closes the hopper outlet 3, the catches 15 getting free
from the pusher on the door reaching its closed position in consequence
3 of horns at their upper inner corners entering notches or cavities in the
On the return outwards of
plates under and against which they slide.
the pusher it opens the hopper door 4 again as it is about completing its

page_text: being opened through the pusher 12 encountering the tumbler catches 15,
and the catches free themselves at the proper time in consequence of
horns on their front upper corners entering cavities provided for the
purpose.
The catches 15 have their action controlled and rendered
certain by springs 16.
The hydraulic cylinder 14 is represented as consisting of a pipe fitted
into end castings 17, 18, through which passages are formed from the
cylinder ends to pipes 19, 20, leading to a middle casting 21. To this
middle casting 21 there is attached a valve box 22, formed with a
cylindrical or slightly coned chamber 23, having in it a valve 24, which
is moved angularly by means of a spindle passing out through a stuffing
box, and having a lever 25 fixed on it. The water is led to the apparatus
by a flexible hose pipe 26, and entering the valve chamber 23 is dis-
tributed to the cylinder passages by the valve 24 acting like an ordinary
slide valve, whilst the water passes off by an exhaust port 27 leading to
a discharge pipe on the middle casting 21, and indicated by dotted circles.
The valve and cylinder passages are represented as made of comparatively
large size, with the view of giving freedom to the movement of the
water, but they might probably be considerably reduced in size without
rendering the action of the apparatus too slow. The valve lever 25 is
connected by a rod 28 to a tumbling lever 29 actuated by water, this lever
being weighted at one side of its fulcrum, whilst at its other side it carries
a box 30, into which a constant small stream of water is led by a pipe 31.
The water accumulates in the box until its weight overcomes the counter-
weight, and then turning down the lever 29 makes it move the valve 24.
The lever 29 is held by a weighted detent lever 32 in the position indi-
cated by the dotted lines until this detent lever 32 is acted on by a hooked
rod 33 fixed to a cross head 34, to which is also fixed another rod 35
passing through a stuffing box into the cylinder 14. When the piston 36
in moving towards the furnace approaches the end of its intended stroke
it encounters the rod 35, and causes the detent 32 to release the weighted
lever 29, which then at once reverses the valve 24, the water having by
that time run out of the box 30 through an outlet, the valve 37 of which
is weighted, and opens by encountering a stop when the box descends.
The piston 36 then returns and draws the pusher 12 outwards, but does
not make the next stroke inwards until the box 30 is again sufficiently

page_text: filled with water, so the length of interval between each action of the
apparatus depends on the rate at which the water is allowed to run into
the box 30, and can be easily regulated by a stop-cock on the supply
pipe 31.
The hydraulic apparatus is mounted on trunnions on a carriage 38
admitting of its being quickly moved away from the furnace mouth
when required, and when in use it is connected to the mouth-piece 6 by
a bracket 39 and pin 40, which can be easily disconnected.
A cover or hood 41 of thin sheet metal is hinged to the front opening
of the mouth-piece 6 to prevent the entrance of air, but which can be
easily opened to remove accidental obstructions or for any purpose. The
middle part of this hood is cut so as to pass down over the piston rod 13
whilst the opening thus left beneath that rod is occupied and closed by a
casing 42 of thin metal, within which the small cross bar 34 moves.
The piston rod 13 is square, so that the pusher 12 cannot turn, and
springs 43 are fitted at each side of the piston 36 to prevent concussive
action at the ends of the strokes.
In my Provisional Specification relative hereto certain arrangements
of rocking fire-bars were described, but I do not now make any claim
respecting such arrangements, as I have not had an opportunity of per-
fecting them, and as I find the ordinary fire-bars 11 to answer very well.
With such bars 11 and with my stoking apparatus I find that with an
average quality of coal dross it is not necessary to clean the fire oftener
than twice in the twelve hours. When such cleaning is to be done the
hydraulic apparatus is disconnected and moved out of the way, carrying
the pusher 12 with it, and on the piece 7, 9, being turned down the fire
can be at once cleaned in the ordinary way. When in its acting position
the plate 9 is held by a rod 44 entered through the cheeks of the mouth-
piece 6 and through lugs cast on the plate 9. Before cleaning the fire I
consider it advantageous to work the apparatus (by moving the lever 29
by hand) a little more rapidly for a short time, so as to supply some
excess of fuel to make up for the diminution of the fire by the cleaning
operation.
}
The pusher 12 is apt to droop as it approaches the inner end of the
furnace, and so if the bars 11 are horizontal make the fire thinner
towards its inner end. If wished this may be corrected either by
inclining the bars downwards towards their inner ends or by inclining

page_text: the hydraulic cylinder upwards; or the parts may be adjusted so as to
give the fire an increasing-depth towards its inner end.
The carriage 38 is represented as having wheels arranged for moving
away in the line of the furnace, but in cases where this is not convenient
the wheels may be set at right angles to those shown, so that the E
apparatus may be moved laterally, a door being fitted in one side of
the mouth-piece 6 to allow the pusher 12 to pass out sideways.
It will be obvious to the practical machinist that the movements of
the pusher may be obtained by means of a rack and pinion or other con-
venient mechanical arrangement. I, however, prefer to use hydraulic 1
apparatus such as is herein-before described.
When the valve 24 is made entirely of metal, as shown, it is necessary
to lubricate it, but the working parts may be faced with lignum vitæ,
which does not require special lubrication.
Instead of the fuel being spread and levelled by the inward movement
of the pusher 12, as herein-before described, it may be carried to the
inner end and then be spread and levelled by the return movement of
the pusher. For this purpose the end of the rod 13 will be fitted, as
shown in end and side elevation in Figures 3 and 4, with a pair of open
frames 45, having two vertical plates 46, between which the fuel falls a
from the hopper upon a horizontal plate 47, fitted to slide on the bottom
bars of the frames 45. Rods 48 are fixed to the plate 47 so as to project
from its inner end, and these rods encountering the fire-bridge or any
suitable stops at the inner end of the furnace on the rod 13 approaching
the inner end of its stroke cause the plate 47 to stop, whilst the outer-
most of the vertical plates 46 still moving inwards pushes the fuel off
the plate 47 down upon the fire, and then on the return movement the
inner vertical plate 46 spreads and levels the fuel over the surface of the
fire. On approaching the end of the return or outward stroke the hori-
zontal plate encountering a stop on the plate 7 is restored to its position a
between the two vertical plates 46.
Having thus particularly described my said Invention and the manner
of performing the same, I have to state that I do not restrict myself to
the precise details herein described or delineated, but that what I believe
to be novel and original, and claim as the Invention secured to me
by the herein-before in part recited Letters Patent is,-
1. The arranging or combining together of the parts of mechanical

page_text: stoking apparatus, substantially in the improved manner herein-before
described.
2. The arranging or contriving of mechanical stoking apparatus so that
a pusher (12) is at intervals moved into the furnace, and pushes before
it and spreads small quantities of fuel on the surface of the fire, sub-
stantially in the manner herein-before described.
In witness whereof, I, the said James Donald, have hereunto
set my hand and seal, this Eleventh day of August, in the year
of our Lord One thousand eight hundred and seventy-five.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
JAMES DONALD. (L.S.)