Improvements in Mechanical Stokers and in Apparatus connected therewith.
Year: 1889

page_text: Date of Application, 23rd Sept., 1889
Complete Specification Left, 21st June, 1890-Accepted, 25th July, 1890
PROVISIONAL SPECIFICATION.
Improvements in Mechanical Stokers and in Apparatus connected
therewith.
1. JAMES HODGKINSON of Wolen Street, Ordsall Lane, Manchester in the County of
Lancaster, Engineer, do hereby declare the nature of my said invention to be as
follows:
1
This invention relates to improvements in mechanical stokers on the ram and coking
principle and in self-cleaning furnaces employed in steam boilers and consists in
arrangements and constructions whereby more reliable and efficient actions are
obtained, and owing to certain unique arrangements and disposition of parts is, in
addition to the ordinary stationary boilers, especially applicable to marine steam boilers;
fully meeting the difficulties which have hitherto prevented the successful application
of mechanical stoking to this class of furnace.
These I accomplish by providing a suitable hopper into which the fuel is placed,
which passes therefrom into shoots leading to each side of the flue, from whence it is
pushed by means of rams, actuated by eccentrics or other mechanical means, into
coking boxes of peculiar form, so arranged as to supply the coked fuel on to the
fire-bars in desired and adjustable quantities. The coking boxes are so arranged
as to be easily applied or renewed, and are constructed so as to make their
are mounted in
displacement witli ordinary working impossible. The rams
guides or casings, and operated as before described to give a reciprocating motion
thereto. The rains and coking boxes are so arranged as to leave a space between
them to provide a fire door sufficiently large to admit of hand firing being resorted
to at any moment.
The door is provided with means whereby the condition of the fire can be ascer-
tained without opening the same, thus avoiding the ill effects arising from the
opening of the door.
My improvements in self-cleaning fire-bars consists in a certain novel method
of constructing, arranging, and moving the bars, which in some respects resemble
those in ordinary use in coal burning fire-grates, and are disposed in a horizontal
or inclined position as may be desired and parallel to each other. The flues of a
boiler are provided longitudinally on each side with side-bars having distance
pieces and air spaces, also pockets to receive bars or bearers to support the movable
fire-bars. The side bars project outside the flue at the front or firing end of the
boiler or furnace, on the ends of which are hearings for supporting the shaft for
operating the bars. The shaft for operating the bars can be of any convenient section,
provided with tappets or cams conveniently mounted, and disposed so as to operate on
the outer ends of the bars to move them out singly, alternately, or in sets, from back
to front of the furnace, for the purpose of carrying forward the fire and clinker to a
chamber at end of bars. Each alternate bar is provided with a lip which extends or
projects over the front end of the next bar, and by which all the bars are moved back
together when the said lips are operated upon by the tappets on the cam shaft. The
bars are provided with straight, stepped, or irregular surfaces. The eccentrics for
operating the rams employed for pushing the fuel into the fire are mounted on the
cam shaft; the latter being driven by worm or other gearing. In applying my
improved strokers and bars to marine boilers with flues or furnaces at varying heights
I can, if desired, drive a whole range from one shaft by any suitable gearing. In
conjunction with my stoker as applied to marine boilers I can, when desired, apply an
elevator or conveyor of special construction for automatically conveying the fuel to

page_text: hopper of stoker, either direct from bunker or otherwise, or by an arrangement of
shoots from bunker to hopper mouth by gravity.
Dated the 21st September 1889.
EDMUND CHADWICK,
Agent.
Improvements in Mechanical Stokers and in Apparatus connected
therewith.
I, JAMES HODGKINSON of Woden Street, Ordsall Lane, Manchester in the County
of Lancaster, Engineer, do hereby declare the nature of my said invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
This invention relates to improvements in mechanical stokers on the ram and
coking principle and in self-cleaning furnaces employed in steam boilers and consists
in arrangements and constructions whereby more reliable and efficient actions aro
obtained, and owing to certain unique arrangements and disposition of parts is not
only applicable to the ordinary stationary boilers but is especially designed to meet
the difficulties which have hitherto prevented the successful application of mechanical
stoking to marine boilers. I provide a suitable hopper into which the fuel is placed,
which passes therefrom into shoots leading to each side of the flue, from whence it is
pushed by means of rams, actuated by eccentrics or other mechanical means, into.
coking boxes of peculiar form, so arranged as to supply the coked fuel on to the
fire-bars in desired and adjustable quantities. The coking boxes are so arranged as
to be easily applied or renewed, and are constructed so as to make their displacement
with ordinary working impossible. The rams are mounted in guides or casings, and
operated as before described to give a reciprocating motion thereto. One important
feature of the arrangement is that the rams and coking boxes are so arranged as to
leave a space between them to provide a fire-door sufficiently large to admit of band
firing being resorted to at any moment. The door is provided with means whereby
the condition of the fire can be ascertained without opening the same, thus avoiding
the ill effects arising from the opening of the door.
My improvements in self-cleaning fire-bars relate to a novel method of constructing,
arranging, and moving the bars, which in some respects resemble those in ordinary
use in coal burning fire-grates, and are disposed in a horizontal or inclined position as
may be desired and parallel to each other. The flues of a boiler are provided longi-
tudinally on each side with side bars having distance pieces and air spaces, also
pockets to receive bars or bearers to support the movable fire-bars. The side-bars
project outside the flue at the front or firing end of the boiler or furnace, on the ends
of which are bearings for supporting the shaft for operating the bars. The shaft for
operating the bars can be of any convenient section, provided with tappets or cams
conveniently mounted, and disposed so as to operate on the outer ends of the bars to
move them out singly, alternately, or in sets, from back to front of the furnace, for
the purpose of carrying forward the fire and clinker to a chamber at end of bars.
Encl alternate bar is provided with a lip which extends or projects over the front end
of the next bar, and by which all the bars are moved back together when the said lips
are operated upon by the tappets on the cam shaft. The bars are provided with straight,
stepped, or irregular surfaces. The eccentrics for operating the rams employed for
pushing the fuel into the fire are mounted on the cam shaft; the latter being driven
by worm or other gearing. In applying my improved stokers and bars to marine
boilers with flues or furnaces at varying heights I can, if desired, drive a whole range
from one shaft by any suitable gearing. In conjunction with my stoker as applied to
marine boilers I can, when desired, apply an elevator or conveyor of special con-
struction for automatically conveying the fuel to hopper of stoker, either direct from

page_text: bunker or otherwise, or by an arrangement of shoots from bunker to hopper mouth
by gravity.
Fig. 1, sheet 1, is a front alevation of my improved mechanical stoker on the ram
and coking principle as applied to marine boilers with flues or furnaces of varying
heights or centres-Fig. 2, sheet 2, is a sectional elevation through, lines A¹ B' in
Figs. 1 and S-Fig. 3 is a side elevation of my improved stoker as applied to marine
boilers with flues or furnaces of varying heights or centres- Fig. 4 is a sectional
longitudinal elevation of my improved mechanical stoker on the ram and coking
principle and self-cleaning fire-bars with their supports and means for operating the
same Fig. 5 is a plan of fire-bars with the stoker removed-Fig. 6 is a longi-
tudinal side elevation of side-bars and supports for carrying the movable or self-
cleaning fire-bars-Fig. 7 is a sectional plan through line CD in Fig. 4-Fig. 8 is
a front elevation of my improved mechanical stoker on the ram and coking principle
as applied to Marine, Lancashire, Cornish, and other boilers or furnaces-Fig. 9 is a
section through line E' Fin Fig. 5 with the rams removed-Fig. 10 is a sectional ele-
vation through line G H in Fig. S-Fig. 11 is a back elevation of fire-door showing
divisions to hold non-conducting material-Fig. 12, sheet 3, is an elevation of a range of
marine boilers fitted with my improved mechanical stoker with means for automatically
supplying the same with fuel, and for driving the same-Fig. 13 is a plan of
same Fig. 4 is a side elevation of Fig. 13 showing the clevator for supplying
fuel from the coal bunkers to the hoppers of mechanical stokers -Fig. 15 is a
side elevation of jaw end of movable bars when being moved backward by the
advance cams-Fig. 16 is a section of a modification of the bearing bar 64
provided with a shaft or centre carrying ferrules to minimise friction when the
lars are sliding thereon-Fig. 17 is an end view showing hearing for the shaft or
contre, and Fig. 18 is a part front view of Figs. 16 and 17.
In all the figures the same numerals are employed to indicate corresponding
parts.
1 is a front view of a marine boiler; 2 the fines or furnaces; 3 the smoke
boxes; 3* the smoke box doors; the framework of the stoker, to which is cast
the fuel hopper 5, and the ram guides or casings 6. The hopper 5 of each marine
stoker is fixed below the smoke box as shown in Figs. 1 and 4, for the purpose
of allowing of the smoke-box doors 3x being opened to clean the tubes 4* or
other purposes without removing the hoppers 5 or interfering with the same, thus
overcoming one of the most serious difficulties hitherto met with in applying
mechanical stokers to marine boilers. Fuel passes from the hopper down the
shoots 7 leading to each side of the flue or furnace, from whence it is pushed by the
moving rams 8 to the coking boxes 21. The rams S are provided with the inclined
pushing surfaces 9 to prevent fuel being lifted or forced back into the shoots 7 leading
to the hopper 5 when making a forward stroke. The upper edge of the ram 8 is
formed with a feather edge to facilitate the breaking of fuel and to minimise friction
when making a forward stroke. To the rams S are secured the centres 10 and links 11
by the nuts 12. The outer ends of the links 11 are attached to the levers 13 by the
centres 14. The levers 13, are fixed to the shaft 15 mounted in the bearings 16 on
the framework or ram-box sides of the stoker. The shaft 15 is fitted with the
slotted levers 17 operated by the eccentrics 18 and rods 19 from the bar shaft 20.
The levers 17 are provided with the slots to allow of the stroke of the rams S being
altered at will to supply fuel in desired or adjustable quantities. As the rams 8 are
moved outwardly the fuel drops from the shoots 7 into the ram guides or casings 6,
from whence it is pushed by each forward movement or stroke of the rams 8 into
the coking boxes 21. By the intermittent action of the rams 8 in supplying fuel to
the coking boxes 21 the coked fuel is pushed on to the fire-bars 22. Owing to the
action of the coking boxes in combination with the sides of the flue some of the fuel,
as it cokes and swells up, falls over the inner edges of the coking boxes towards the
centre line of the furnace so as to feed the area along the central fire-bars. The
external sides of the coking boxes 21 are formed as shown in Figs. 2, 3, 4, and 9,
to allow of the coked fuel passing to the sides of the flues or furnaces to ensure

page_text: even distribution. The coking boxes 21 are provided on one side or edge with the
lip 23 fitting into the recess or chamber 24 on the backside of the framework 4 of the
stoker; the other side being fitted with the lug or snug 25 to allow of its being
secured to the framework by the bolt 26 as shown in Fig. 9. This arrangement
allows of the coking boxes 2.1 being easily applied and removed, but prevents their
displacement with ordinary working. Under the coking boxes 21 it is convenient to
provide the passages 27 to admit atmospheric air to aid combustion. Below the
framework of the stoker is fixed the dead plate 28 which may have an air space
between its upper side and the underside of the framework 4 to admit atmospheric
air to aid combustion. The rams S, guides or casings. 6, and the coking boxes 21
are disposed sufficiently apart as to leave a space between them to allow of the fire-
door 29 sufficiently large to admit of hand firing being resorted to at any moment in
case of accident to the mechanical stoker or otherwise as desired. The fire-door 29
is provided with the centres 30 supported in the bearings 31 on the plate 2 secured
to the framework 4 by the bolts 33. The heat at the front of the furnace is
so great as to rapidly burn away the ordinary fire-door. To provide against this I
form the door in the shape of a grid the spaces 34 in which are filled with fire-clay,
asbestos, or other refractory materials or compounds. The spaces 34 are made taper as
shown so as to hold the refractory materials in place. Holes 35 may be provided to
admit of atmospheric air passing through to aid combustion. The fire-door 29 is fitted
with the opening 36 over which fits the pivoted door 37 to allow of the condition of
the fire being ascertained without opening the fire-door 29, thus avoiding the ill
effects arising from the opening of the litter. The fire door 29 is fitted with the
hook 38 and chain 39-the latter passing over the pulley 40-to open the same
when desired.
It will be seen on examining Fig. 1, sheet 1, that owing to the varying heights of
the flues or furnaces in marine boilers that the bar shaft 20 passes through the fuel
hopper 5 of the stoker attached to the bottom flue or furnace.
In carrying out my improvements in self-cleaning fire-bars the heads 41 are
secured to the framework of the stoker by the bolts 42. In the heads 41 are
disposed the adjustable sliding blocks 43 carrying the bar shaft 20. The sliding
blocks 43 are fitted with the adjusting screws 44 passing through the threaded
plates 45 secured to the jaw ends 46 of the heads 1 by the bolts or set screws 46.
After the sliding blocks 43 have been set by the adjusting screws 44, they are locked
in position by the nuts 47 mounted thereon. The back side of each head 41 is
provided with the lodge or support 48 in which the front end of the side bars 49 rest,
being secured in position vertically to the side flange 50 on the head 41 by the bolts 51.
The back end of each side bar 49 is fitted or secured to the bridge plate 52 by the
bolts 53 as shown in Fig. 6. The side-bars 49 are furnished on the sides next to the
casing forming the flue or furnace with the distance pieces or supports 54, on which
are placed the air grids 5 as shown in Fig. 5. The inner side of each side bar 49 is
provided with the pockets 6 carrying the bars or bearers 57 to support the movable
fire-bars 22. To the latter are cast the distance pieces 58 to determine sufficient air
space between each bar. The shaft 20 for operating the movable fire-bars 22 can be of
any convenient section; the ends being provided with the bushes 59 mounted in the
sliding blocks 43 in the heads 41. The shaft 20 is fitted with the loosely mounted
cams or tappets 60 and distance washers 61 between each cam or tappet. The cams
or tappets 60 are disposed on the bar shaft 20 so as to operate on the lips. 62 on the
outer ends of the movable bars 22 in such a manner as to move them out singly,
alternately, or in sets, from back to front of the furnace. In the case of moving the
bars 22 out singly or alternately one half of the cars or tappets 60 are set in advance
of the other half as shown in Figs. 4 and 15. Immediately the cams or tappets 60
have moved the first half or other portions of the fire-bars 22 outwardly their full
travel the remaining cams or tappets 60 bring or force out the remainder. Each
alternate bar 22.is provided on the lower end of the front jaw with the lip 63, which
extends or projects over the front end of the next bar as shown in Figs. 1, 7, and S.
The movable fire-bars 22 with the lips 63 are moved outwardly in advance of those

page_text: without the said lips by the cams or tappels 60. When the movable bars without the
lips 63 have been moved outwardly the front end of the lower part of the jaw is in
contact with, or nearly so, the back side of the lips 63. Immediately all the bars 22
have been moved or drawn out to their full extent and the last set of cams or
tappets 60 are clear of the lips 62 the advance cams or tappets 60 operate on
the front side of the lips 63 as shown in Fig. 15, by which all the bars 22 are
moved back together to carry the firo on to make room for a fresh supply of
fire or fuel from the coking boxes 21, and so on continuously as long as the
mechanical stoker is in motion To maintain the correct working position and
prevent canting of the movable fire-bars 22 under all conditions the bar or support 64
is provided and placed under the jaw ends of the said bars, being secured to the
underside of the heads 41 by the bolts or set screws 65 as shown in Figs. 1, 6,
and S. If it is desired to reduce or minimise the friction between the underside
of the jaw ends of the bars 22 and the bar end or support 64 the latter is fitted
with the ferrules 66 mounted on the centre 67 as shown in Figs. 16 and 18. The
upper surface of each fire-bar 22 is made with stepped or irregular surfaces as.
shown in Fig. 4, by which the fuel or fire lying thereon is rammed or pushed on
towards the back end of the bars to the combustion and clinker chamber 68 by the
raised edges or projections 69. These projections with the upper surface of the bar
are shaped as shown so that the effect on the fiel of the inward motion of each.
bar is as great as possible whilst the effect of the outward movement is as small
as possible. The bar shaft or shafts 20 extend to the fixing 70, and are supported
in the bearings 71 as shown in Figs. 1, 12, and 13. The outer end of each bar shaft 20:
is provided with a worm wheel driven by the worms 72 on the shaft 73 supported in
the bearings 74 on the fixing 70. On the shaft, 73 is fixed a worm wheel driven by
the worm 75 on the shaft 76, which is connected to the engine shaft or other driving;
médium in any convenient manner according to the speed at which it is desired or
necessary to rotate the same.
In applying my improved stokers and fire-bars to marine boilers with flues or-
furnaces at varying heights 1 drive a whole range from the shaft 76 as shown in
Figs. 12 and 13. In these figures it will be seen that the shaft 76 is driven direct
from the engine shaft 77 by the bevel or other wheels 78. In this arrangement the
marine boilers are disposed opposite each other, both sides being driven alike. In
case of other rows of boilers as is often the case in large sea-going steamers-the
engino shaft 77 is extended as shown in Fig. 13, from whence they can be driven by
bevel or other wheels 78 or gearing as desired. The shaft 77 is driven by the
engine 79 firmly secured to the bunker 80 or otherwise.
On examination of Figs. 12, 13, and 14 it will be seen that I can automatically feed
the hopper 5 of each mechanical stoker with fuel direct from the coal bunker. This I
effect by means of the ordinary bucket elevator 81 fed by the creeper 82; the latter
being driven from the engine shaft 77 by wheel or other gear. As the elevator 81
rotates or traverses the fuel is tipped down the shoot 83 into the trough 84, from
whence it is carried by the screw or creeper 85 to the shoots S6 leading to the-
hoppers 5 of the stokers.
In case the coal bunkers are disposed at a point above the hoppers 5 of the
stokers the fuel is fed by gravity into the trough 84 containing the screw or
creeper 85, and on to the shoots leading to the said. hoppers. Suitable mechanical
appliances can be fitted to the shoots S6 for regulating the supply of fuel to the.
hoppers.
Having thus stated the nature of my invention and described the mode of per-.
forming the same, I would have it understool that I do not confine myself to the
precise details or configuration of the parts. I have shown and described, which are
obviously capable of considerable variation without departing from the principles of
my invention, also, that I am aware that it is not new in mechanical stokers to
carry the fire-bars together inward, and outward singly, alternately, or in seis, and
.

page_text: that I make no broad claim to such arrangement, but what I claim and desire to be
secured to me by Letters Patent is :-
1. A mechanical stoker arranged with a fire-door of ordinary size having a ram
and coking box on each side of it, and with the hopper and driving gear so placed
as to permit the opening of the smoke-box door, substantially as hereinbefore
described.
2. The rams 8 provided with the inclined surfaces 9 for the purpose specified
substantially as described.
3. The construction and arrangement of the coking boxes 21 disposed on each
side of the fire-door 29, and secured to the framework of the mechanical stoker, sub-
stantially as described
4. The construction and arrangement of the fire-door 29 provided with the taper
divisions or spaces 34 to retain refractory material, with or without the holes 35 to
admit atmospheric air through the said non-conducting material to aid combustion,
substantially as described.
5. The construction and external arrangement of parts for operating the rams 8
from the bar shaft 20, substantially as described.
6. In combination with movable self-cleaning fire-bars the employment of the lips 63
for the purpose of moving all the bars back together when operated upon by the
advance portion of the cams 60, substantially as described.
7. Providing self-cleaning fire-bars with stepped surfaces substantially as shown
in order to facilitate the forcing of the fuel or fire lying thereon towards the
back end of the furnace.
S. The arrangement of the heads 41 secured to the framework of the stoker and
provided with means for supporting the outer ends of the side-bars 49, substantially
as described.
9. The use of the external bar 64, with or without the rollers 66, for supporting
the front ends of the movable fire-bars 22, and for steadying and inaintaining the
position of the side-bars 49 and the heads 41, substantially as described.
10. The arrangement of the cam tappets CO in relation to the lips and projections 63
and 62 on the heads or jaws of the fire-bars, so that the fire-bars are carried
inwards together and outwards singly, alternately, or in sets, by the action of the
tappets, substantially as described.
11. The general combination and arrangement of parts constituting my improved
mechanical stoker on the ram and coking principle for supplying fuel in desired
and adjustable quantities to furnaces of marine and other boilers, applied and operating
substantially as described.
12. The combination and arrangement of mechanism for automatically supplying
fuel direct from the coal bunkers to the hoppers of mechanical stokers applied or
fixed to marine hoilers, substantially as described.
Dated the 19th June 1890.
EDMUND CHADWICK,
Agent.