IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES
Year: 1878

page_text: LETTERS PATENT to William Jackson Hunter, of Kinfauns, in the County of
Perth, North Britain, Engineer, for the Invention of "IMPROVEMENTS IN
STEAM BOILER AND OTHER FURNACES."
Sealed the 23rd August 1878, and dated the 26th March 1878.
PROVISIONAL SPECIFICATION left by the said William Jackson Hunter at
the Office of the Commissioners of Patents on the 26th March 1878.
WILLIAM JACKSON HUNTER, of Kinfauns, in the County of Perth, North Britain,
Engineer. "IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES."
This Invention has reference to new or improved simple arrangements of motive
power travelling grates or grate bars for the automatic feeding-in of the fuel to
steam boiler and other furnaces, whereby a more regular supply of fuel and a more
uniform combustion and heat will be kept up within these improved furnaces so
constructed and fitted, with a great saving of manual labour in stocking and
keeping the furnace fires in order.
These improved furnaces are applicable to furnaces within the internal flues of
marine or land steam boilers, and also to furnaces constructed within the brickwork
below steam boilers, or for heating furnaces generally.
And the nature and novelty of the Invention or improvements consist in forming
the furnace bars rather shorter than the width of the furnace, and in setting them
transversely across the furnace, close, side by side, and ranged and carried by their
ends to travel or traverse in a double-grooved longitudinal side frame or frames,
secured close up to the two sides of the furnace flue, chamber, or fire-place, in two
rows, with semicircular guides jointing the seat the outer and inner extreme ends of
this new or improved travelling furnace grate. These guide frames with their double
row of transverse travelling furnace bars are continued a sufficient distance out in
front of the furnace flue door, or other furnace doors, to form the fuel charging or
feeding hearth, as two feet or so, which receive the coal.or other fuel from a hopper
or other inclined shoot, with its open mouth delivering on to the upper set of

page_text: furnace bars in front of the furnace doors, which would be mounted in slides or
other equivalent to regulate the depth of fuel to pass in below them with the upper
furnace bars as they are pushed in at a slow but regular speed proportionate to the
rate of combustion, actuated by a transverse shaft working in journal bearings in
the outer semicircular part of the guide frame, with pitched grooved wheels taking
into the inner edges of the two rows of furnace bars at this extreme outer end to
raise the furnace bars from the lower returning row up and round the guides, on to
and along the upper row, which as they are pushed forwards or inwards would
carry the fuel into the furnace with them under the furnace door, and right through
the furnace to the back bridge, by which time the fuel would be burned to ashes,
where the furnace bars would be forced round and down the back guide grooves
along the under grooves and line of bars (to their front raising and moving shaft
and pitch wheels) in an inverted position, emptying all the ashes and waste residues
of the burned fuel into the back part of the ash-pit, while the small ashes falling
through the air spaces between the upper set of bars would more easily find their
way through the inverted lower set of bars. The motion of the bars shaking the
fuel and fire would assist the escape of the ashes and keep the fire-grate clean to let
in the air, and maintain a bright clear fire throughout the whole length, right back
to the flame bridge. .. ⠀
In some cases, when preferred, a revolving shaft with guide pitch chain wheels,
similar to those at the front end, may be mounted at the back semicircular guides
of the furnace to guide the bars in regular order down and round from the top row
to the under return row and guides. The front shaft with its pitch wheels for
traversing the forward and return set or chain of furnace bars might be driven at a
slow speed by a screw wheel on it and screw working into it, the shaft of which
might be driven by the engine driver by the steam from the boiler, or from any
convenient adjacent motive-power shaft or other slow motive gearing fitted thereto
for the said purpose; and when desired a longitudinal screw shaft could be fitted
at one side of the ash-pit and furnace bars to actuate both the outer and inner
shafts of the driving and guiding pitch wheels at the same slow rate of motion.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Jackson Hunter in the Great Seal Patent Office on the
26th September 1878.
WILLIAM JACKSON HUNTER, of Kinfauns, in the County of Perth, North Britain,
Engineer. "IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES."
My said Invention has reference to new or improved simple arrangements of
motive-power travelling grates or grate bars for the automatic feeding-in of the fuel
to steam boiler and other furnaces, whereby a more regular supply of fuel and a
more uniform combustion and heat will be kept up within these improved furnaces
so constructed and fitted, with a great saving of manual labour in stoking aud
keeping the furnace bars in order.
These new or improved motive-power or automatic arrangements or constructions
of stoking furnaces are applicable to furnaces within the internal horizontal flues of
marine or land steam boilers, and also to furnaces constructed within the brick work
below land steam boilers, or for heating furnaces generally, with very slight
alterations or modifications of the details.
And in order that the nature, novelty, and mode of performing my said Inven-
tion may be properly understood, I shall now proceed to describe the several
Figures on the Sheet of Drawings which I have hereunto appended for that
purpose, the same reference letters and numerals indicating the same or like parts
in all the Figures where shown.
Figures 1 and 2 are a longitudinal vertical section and a horizontal section
respectively, corresponding to and taken on the line 1--1 and 2-2 in each other
of a duplex arrangement or modification of my new or improved motive-power or
automatic stoking furnace and its fittings generally, as applied to and within the
front end of an ordinary two-flue or horizontal furnace cylindrical steam boiler, all
constructed in accordance with and illustrative of the nature and mode of putting
my said Invention into effect or practice; and Figures 3 and 4 are a transverse
section and a sectional end elevation of the same arrangement corresponding to and
taken on the lines 3---3 and 4---4 in Figures 1 and 2.
Figures 5 and 6 are a sectional side elevation and transverse section to a large
scale detached, with parts broken away, of the new or improved continuously-
moving grate bars A, A', and their motive shaft D and gear, all to show the details
of combustion more clearly than can be seen in the general arrangements, Figures
1 to 4; and Figures 7 to 9 are enlarged detailed views of the moving furnace
bars A, detached to show their construction more clearly.
Referring to these Figures, 1 to 6, the nature and novelty of the Invention or
improvements consist in forming the furnace bars A, A', rather shorter than the width
of the furnace B and flue of the boiler Z, and in setting them transversely across
the furnace B close, side by side, and ranged and carried by their broad ends A¹¹ to
travel or traverse in the double grooves C¹, C", in the longitudinal side frame or
frames C, C, with transverse stays c secured close up to the two sides of the furnace
flue, chamber, or fire-place B, z, in two rows, with semicircular guide grooves C¹¹¹,
jointing these at the outer and inner extreme ends of this new or improved furnace.
B, C, and travelling grate A, A¹. These guide furnaces C, C, (which may be made
adjustable to compensate for the wear and tear of the bars) with their double row
of transverse travelling furnace bars A, A¹, are continued a sufficient distance out
in front of each furnace flue B, 2, and ordinary or other furnace door B' to form the
fuel charging or feeding hearth at B" (as two feet or so), which receives the small
coal or other fuel from a hopper or other inclined shoot S, with its open mouth B'
delivering on to the upper set of furnace bars A in front of the furnace B or door B¹,
which would be mounted in slides B with actuating levers b and weights b², or
other equivalent, to regulate the depth of fuel to pass in below the door. B¹ with
the upper furnace bars A, as they are pushed in at a slow but regular speed, pro-

page_text: portionate to the rate of combustion, actuated by the transverse shaft D working
in journal bush bearings D' in the outer semicircular part of the guide frames C,
with pitched grooved wheels E, e, keyed on the opposite ends of the shaft close up
to the frames C, C, into which the inner end edges a of the two rows of furnace
bars A, A, enter or take at this extreme outer end to raise the furnace bars
from the lower returning row A', up and round the guide grooves Cll of the
frames C, on to and along the upper groove C₁ and row A, which, as they are
pushed forward or inwards, would carry the fuel into the furnace with them from
the furnace door B¹, and right through the whole length of the furnace A, B, to the
back B, where the upper range of furnace bars A are forced forward round and
down the back semicircular guide grooves C¹¹, back along the under grooves C³,
bringing the line of bars A¹ back in an inverted position to their front raising and
moving shaft and pitch wheels D, E, e, so as to be raised by these, and again led
and forced forwards, as before explained, constantly emptying all the partially
burned fuel in an incandescent state at B into an ordinary back burning and
heating chamber B³ (fitted with a hinged or sliding door ¹¹ separating it from the
ash-pit 2, and for regulating the admission of air to the chamber B³), when the fuel
is burned therein between the end of the furnace bars B and the usual back-flame
bridge; which however in some cases might be built close up to the back end B¹¹¹
of the bars and furnace A, B, as when the fuel is fed in at a rate to be quite burned
to ashes or clinkers, which in that case would be delivered down into the back
part of the ash-pit z¹. The motion of the bars would cause the smaller ashes to
fall freely through the air spaces between the upper set of bars A, and then pass
more easily through the inverted lower set of bars A', while this motion of the
bars A would also assist in shaking and keeping a clean open grate and fire for
the admission of the air, so as to maintain a bright clear fire over the whole width
and length of the upper grate bars A, A, to the back chamber B³, or right back to
the flame bridge when that is desired.
The arrows in the Figures indicate the motion of the parts and admission of air
to the furnace, and the darts indicate the motion of the heated products of com-
bustion and flarnes from the fuel and fire. The feeding-in hopper S is shown of a
plain hollow angular or wedge shape, nearly the full width of the furnace, for
receiving small coal or other fuel to be fed into the furnace B through the inner
sliding door B, and is fitted with an outer hinged, or, it might be, sliding door S'
in front of the feeding door B' at the lower end close down to the furnace bars A,
so as to be able to examine the working of the fire-grate or state of combustion,
and put anything to right by the ordinary long-hand fire tools from the furnace
mouth when that is required.
The front shaft D with its pitch wheels E, E, e, for traversing the forward and
return set or detached chain of furnace bars A, A¹, may be driven at a slow speed, as
shown in Figures 1, 4, and 5, by a ratchet wheel F on cach shaft D actuated by a
loose oscillating weighted lever G, G, and pawl g, g', taking into the teeth f of the
ratchet wheel F on the up stroke of the lever G raised by the lower slotted end h of
the reciprocating connecting rod H attached to and actuated at the upper end by a
crank or eccentric for each, on an overhead slow-motion shaft for the purpose, not
shown in the Drawings, this being a common mechanical motion. But this motion
of the shaft D might also when desired be effected by a simple arrangement of screw
wheel fixed on it, and a screw working into this on a screw shaft which might be
actuated by gearing from the motive engine driven by the steam from the boiler Z
of the furnace A, B, or it might be from any convenient adjacent motive-power
shaft or other slow motive gearing fitted thereto for the said purpose.
In some cases, when preferred, a revolving shaft D with guide pitch wheels E, E, c,
similar to those at the front end, may be mounted in the centre of the back semi-
circular guide grooves C1 of the furnace frames C, O, to guide the bars A, A¹, in
regular order down and round from the top row A to the under return row A² and
guides C¹.
When desired an endless pitch chain or chains may be used to drive the back.

page_text: shaft from the front shaft D, which might also actuate or traverse the furnace
bars A, A, direct, or otherwise a longitudinal screw shaft could be fitted at the
side of the ash-pit and furnace bars to actuate both the outer and inner shafts D, D,
(where two are used) with their driving and guiding pitch wheels E, E, and furnace
grate bars A at the same slow uniform rate of motion.
The furnace bars A may in some cases be formed with slots a' at their sides and
upper edges, preferably angled in reverse directions, as indicated in Figures 7 and 9
in dotted and sharp lines respectively, for the freer admission of air and the
keeping of the bars cool; or the bars may be made with openings through them,
as is usual for this latter purpose, and plates c¹ may be fitted on the top of
the frames C of the furnace, formed either with or without air openings, for
filling up the furnace grate or hearth right out to the full width of the flue =
and preventing the burning fuel from falling down into the ash-pit along the
sides.
Although the furnace bars A have been shown as formed, raised, lowered,
and traversed separately, it is to be understood that two, three, or more might
be cast in one, or in the form of sections of transverse furnace grates, and raised,
lowered, and traversed in such sections, all otherwise substantially as described, and
shown in reference to the single bar system shown in the Drawings.
Having now described the nature of my said Invention, and the manner of per-
forming the same, I have to state that I do not confine myself to the precise details
herein described or delineated, but what I consider novel and original, and there-
fore claim as the Invention secured to me by the herein-before in part recited
Letters Patent is,―
First. The general construction or arrangement and combination of the parts of a
new or improved stoking furnace and its fittings, with inward and return moving
sets of transverse grate bars in steam boiler and other furnaces, all substantially as
herein-before described in reference to and shown in the accompanying Drawings,
or any mere modification thereof.
Second. The construction, arrangement, and use of inward and return moving
transverse bars A, a, or sections of furnace grates in motive-power or automatic
stoking steam boiler or other furnaces, substantially as herein described in
reference to, and shown in the accompanying Drawings, or any merc modification
theroof.
Third. The construction and use of grooved side frames C, C, for carrying and
guiding the inward and return moving transverse bars A, a, or sections of furnace
grates in motive-power or automatic stoking steam boiler, or other furnaces, sub-
stantially as herein described in reference to, and shown in the accompanying
Drawings, or any mere modification thereof.
Fourth. The construction and use of transverse end shafts D with pitched wheels E
for raising, lowering, and actuating the inward and return moving transverse
bars A, a, or sections of furnace grates in motive-power or automatic stoking steain
boiler or other furnaces, substantially as herein described in reference to, and shown
in the accompanying Drawings, or any mere modification thereof.
In witness whereof, I, the said William Jackson Hunter, have hereunto set my
hand and seal, this Twenty-fifth day of September, in the year of our Lord
One thousand eight hundred and seventy-eight.
Witness,
W. R. M. THOMSON,
Patent Agent,
Glasgow
W. J. HUNTER. (L.S.)