IMPROVEMENTS IN MECHANICAL STOKING APParatus for Boiler and OTHER FURNACES
Year: 1875

page_text: LETTERS PATENT to James Smith, Engineer to Messieurs Walter
Crum and Company, of Thornliebank, in the County of Renfrew,
North Britain, for the Invention of "IMPROVEMENTS IN MECHANICAL
STOKING APParatus for Boiler and OTHER FURNACES."
Sealed the 3rd August 1875, and dated the 8th February 1875.
PROVISIONAL SPECIFICATION left by the said James Smith at the
Office of the Commissioners of Patents, with his Petition, on the
8th February 1875.
I, JAMES SMITH, Engineer to Messieurs Walter Crum and Company,
of Thornliebank, in the County of Renfrew, North Britain, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN MECHANICAL
STOKING APPARATUS FOR BOILER AND OTHER FURNACES," to be as follows, that
is to say:-
This Invention relates to improvements in mechanical stoking
apparatus for supplying fuel to and moving it forward in boiler and
other furnaces in a regular manner, the objects being to simplify the
construction and working of the parts and to render the apparatus more

page_text: efficacious and satisfactory than heretofore and less liable to get out of
order.
In carrying out the Invention there is fitted at the mouth of the
furnace a hopper which is at its lower as well as upper part of the full
width or nearly so of the grate surface. The front ends of the fire-
bars form the bottom of the hopper, and the fuel passes from the hopper
into the furnace under a lifting plate or door, the height of which is
adjusted to suit the amount of feed desired. In the bottom part of the
hopper two short screws are fitted for the purpose of applying a positive
pressure inwards to the fuel to enable the freshly entering fuel to force
its way against any resistance that may be caused by the caking or
agglomerating of the fuel further in. The fire-bars which are disposed
longitudinally are of a form presenting an inverted channel section
transversely or like that which two ordinary bars would have if united
along the top. In longitudinal vertical section the bars are made and
placed with a general downward inclination towards the inner end of the
furnace, but they have at each of two points a more or less abrupt drop,
and at these points apertures are formed through which two series of
rods or pokers can project inwards over the lower parts. The rods or
pokers are connected to a rocking shaft or are made to reciprocate in
any convenient way, and they push the fuel gradually inwards and
prevent its adherence to the bars. By the action of the pokers favored
by the general declivity of the grate surface the fuel progresses in a
regular manner towards the inner end of the furnace whilst it is being
consumed, and the ashes or residues finally drop over the inner ends of
the bars into the ash-pit.
A revolving shaft driven continuously or intermittently but regularly
gives motion to the screws through worm and worm wheel or other
gearing, and to the rocking shaft to which the pokers are connected by
a cam or eccentric.
The details may be varied according to the sizes and peculiarities of
different furnaces; thus in wider furnaces there may be more than two
screws, and in longer ones more than the two sets of pokers, whilst in
some cases a single screw or single set of pokers may be sufficient.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Smith in the Great Seal Patent Office on
the 6th August 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
5 SMITH, Engineer to Messieurs Walter Crum and Company, of Thornlie-
bank, in the County of Renfrew, North Britain, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth 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 Smith, Her special
licence, that I, the said James Smith, my executors, administrators,
and assigns, or such others as I, the said James Smith, my executors,
administrators, 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 BOILER AND OTHER FURNACES," upon
the condition (amongst others) that I, the said James Smith, my execu-
tors or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and
ascertain 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 immediately
after the date of the said Letters Patent.
NOW KNOW YE, that I, the said James Smith, 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 accom-
panying Drawings, that is to say:―
My said Invention relates to improvements in mechanical stoking
apparatus for supplying fuel to and moving it forward in boiler and
other furnaces in a regular manner, my objects being to simplify the
construction and working of the parts and to render the apparatus more

page_text: efficacious and satisfactory than neretofore and less able to get out of
order.
My Invention consists mainly in arranging screws to push forward
fuel descending from a hopper upon the front ends of fire-bars of a
peculiar construction, combined with the application of a set or sets of
reciprocating pokers which stir the fuel and push it gradually inwards
to the inner end of the furnace, the ashes or exhausted residues finally
falling into the ash-pit through an opening at the front of the bridge.
And in order that my said Invention and the manner of performing
the same may be properly understood I hereunto append a Sheet of
explanatory Drawings to be hereinafter referred to, and representing a
modification of my improved mechanical stoking apparatus as fitted to a
pair of steam boiler furnaces. 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 front elevation, and Figures 2 and 3
are longitudinal, horizontal, and vertical sections.
At the mouth of each furnace 1 there is fitted a hopper 2, which is at
its lower as well as at its upper part of the full width, or nearly so, of
the grate surface; the front ends of the fire-bars 3 extend forwards
under the hopper 2, and the fuel passes from the hopper into the furnace
under a lifting plate or door 4, the height of which is adjusted to suit
the amount of feed desired; each door 4 is suspended by chains from
pulleys 5 on a transverse horizontal shaft, having a hand wheel 6 at its
outer end, and a catch gearing with a ratchet wheel on the shaft holds
the door in any required position; in the bottom part of each hopper 2
two short screws 7 are fitted for the purpose of applying a positive
pressure inwards to the fuel to enable the portion of fuel freshly entering
the furnace to force its way inwards against any resistance that may be
caused by the caking or agglomerating of the fuel further in. The fire-
bars 3 which are disposed longitudinally in the furnace being supported
by transverse bearers 8, 9, at their front and back ends, are of a form
presenting an inverted channel section transversely. In longitudinal
vertical section the bars 3 are made and placed with a general downward
inclination towards the inner end of the furnace, but they have at each
of three points 10, 11, 12, a more or less abrupt drop, and at these points
there are formed apertures through which three series of rods or pokers 13

page_text: can project inwards over the lower ports, whilst slots 14 are formed in
the nearly horizontal parts for the passage of air upwards from the ash-
pit 15. The rods or pokers 13 are all jointed at their front ends on a
bar 16 carried by a pair of levers 17 fixed on a rocking shaft 18, or the
pokers may be made to reciprocate in any convenient way; and they
push the fuel gradually inwards, and by acting immediately over tho
surface of the fire-bars 3 prevent the adherence of fuel thereto.
By
the action of the pokers 13, favored by the general declivity of the grate
surface, the fuel progresses in a regular manner towards the inner end
of the furnace whilst it is being consumed, and the ashes or residues
finally drop into the ash-pit 15 down a gap 19 left between the inner
end of the fire-bars 3 and the bridge 20. Air has access to the fire not
only through the slots 14 in the fire-bars 3 but also through notches in
otherwise plain bars 21 at the extreme sides of each furnace space, and
also through boxes 22 with perforated inner ends, and placed on the
front ends of the fire-bars 3 between the two screws 7.
A revolving shaft 23, which may be driven continuously or inter-
mittently but regularly gives motion to the screws 7, the spindles of
theso screws having worm wheels 24 on their outer ends in gear with
worms on the shaft 23, and this shaft also gives motion to the rocking
shaft 18 to which the pokers 13 are connected. A lever 25 fixed on the
rocking shaft 18 has jointed to it a bar 26, the upper end of which can
work through a guide. This bar 26 is formed, as is best seen in Figure 4,
with a cam-formed part 27 shaped so as to be acted on in the desired
manner by a pin 28 placed eccentrically on a disc or wheel on the
revolving shaft 23.
The rocking shaft 18 is not moved at every
revolution of the shaft 23, but only once every turn of the worm
wheel 24 (that is in ordinary cases about twice every minute). The
bar 26 is attached or set so as to tend to spring away from the eccentric
pin 28, and is pushed into the way of it at intervals by a sliding pin 32,
which is acted on by a small wiper 33 on the boss of the worm
wheel 24.
The separate shafts 23 of the two furnaces are represented as driven
by endless chains 29 from an overhead shaft 30, having on it fast and
loose pulleys for a driving belt. Stepped sets of sprocket wheels 31 are
shown as provided for the endless chains 29 to admit of the speed trans-
mitted being altered when required.

page_text: The details of my improved stoking apparatus may be varied according
to the sizes and peculiarities of different furnaces, or to suit different
qualities of coal or fuel. Thus in wider furnaces there may be more than
two-screws (7), and in longer ones more than three sets of pokers (13),
whilst in other cases on the contrary fewers screws and pokers will
suffice.
Having thus particularly described my said Invention, and the
manner of performing the same, I have to state 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 constructing and arranging of grate bars and the using of
reciprocating pokers in connection therewith, substantially in the
manner herein-before described.
2. The combining of the screws (7) with the peculiar grate bars (3)
and the reciprocating pokers (13), all arranged and operating sub- 1
stantially as herein-before described.
In witness whereof, I, the said James Smith, have hereunto set
my hand and seal, this Fourth day of August, in the year of our
Lord One thousand eight hundred and seventy-five.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
JAMES SMITH. (L.S.)