IMPROVEMENTS IN MECHANICAL! STOKING FURNACES FOR STEAM BOILERS AND OTHER PURPOSES
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by John Lockwood at the Office of the
Commissioners of Patents on the 27th October 1879.
JOHN LOCKWOOD, of Glasgow, in the County of Lanark, North Britain, Engineer.
"IMPROVEMENTS IN MECHANICAL! STOKING FURNACES FOR STEAM BOILERS AND
OTHER PURPOSES."
This Invention has reference to certain improvements and combination of the
parts of mechanical or automatic stoking furnaces, which improvements will
make such furnaces more simple and efficient in their action than they have been
heretofore.
And the nature and novelty of the Invention consist as follows:-The set of
furnace bars are ranged much as usual to slide nearly horizontally on a cross bar at
the back or inner end of the furnace, and on a similar bar at the front or mouth of
the furnace, which furnace bars may be of any of the ordinary constructions here-
tofore in use, but having long ends projecting out in front of the feeding door of the
furnace, under, and so as to form the bottom of a feeding-in hopper in front, kept
full and supplied regularly with dross or other fuel. The entrance front ends of the
bars are also carried on a cross guiding bar secured to the strong front side frames,
supporting the hopper, and the journal or bush bearings of the driving or stoking
shafts and gearing all in front underneath the projecting ends of the furnace bars,
which may have projections on them for stopping them at the extreme inner
positions of their motion.
The hopper is formed with a vertical sliding door in front of the furnace, raised
and lowered off the furnace bars by racks on the sliding door, and pinions on a cross
shaft or other equivalent means so as to regulate the opening below or above the
furnace bars for the thickness of fuel to be fed in from the hopper by the reciprocatory
motion of the furnace bars, as will hereinafter be described. The front inclined side
of the hopper is made in the form of a sliding door, which may either be removed
or sufficiently raised off the furnace bars at the extreme front end, so as to be able
to hand stoke the furnace or clean or manipulate it when desired.
Motion is given to the furnace bars by two revolving shafts mounted underneath
the bars, and geared to each other by spur wheels at one side of the stoking or
hopper frame outside the furnace. Each furnace bar has a short vertical arm pro-
jecting down between the shafts, so that a revolving crank spindle with an anti-
friction roller on it right across the front shaft acts on the outer face of the short
n

page_text: vertical arms of the bars, so as slowly to pass forward the whole set of furnace bars
at once, to the extent of the throw of the crank (which may be from two to six
inches so as to feed in the fuel with, and resting on the top of the furnace bars to a
depth regulated by the lower edge of the feeding door.
While the inner shaft brings back the furnace bars in alternate sets intermittently
by two or it might be three rows of short tappets or levers divided at right angles,
or other angles when there are three rows acting on the inner face of the short
vertical arms on the furnace bars, so as to bring back each alternate or third bar, in
two or three sets, slowly and gradually without the power of carrying back the fuel
on the bars. And intermittent motion is given to either of these geared shafts by a
ratchet wheel on its one end, from a first motion revolving shaft, supported on
bearings beneath the hopper or in any other convenient position and driven by speed
cone pulleys and belts or otherwise, from any convenient or adjacent motive shaft.
This first motion revolving shaft has fitted on its one end a crank or disc pin,
with a connecting rod having its forward free end coupled to a differential
reciprocating lever with ratchet pawl taking into the teeth of the ratchet wheel of
the shaft to be actuated as before stated; the ratchet lever is fitted with a slot to
alter the length of the throw of its connecting rod pin to take up any convenient
number of teeth of the ratchet wheel at each throw of the ratchet paul lever and
revolution of the crank revolving shaft according to the speed and feed of fuel
desired to be given to the furnace bars. But it will be evident that other feeding
arrangements might be adopted for the actuating of the two geared tappet or
stoking shafts such as a screw and worm feed or band and cone pulley feeding
gear. The inner ends of the furnace bars are preferably made bevilled down to the
rear bearing bar on which they rest which forms part of the back bridge of the
furnace, and this bridge is by another improvement made to incline upwards and
backwards from the cross bar so as to form an angled recess of the depth of the
bars in front, and of the height of the bridge at the back, which angled bridge is
sufficiently high to prevent the burning fuel from being carried over until nearly
consumed and so regulate the depth of the fire on the furnace bars. The
reciprocating motion of the furnace bars drives the incandescent fuel or fire over
the inclined bridge into the ashes chamber at the back end of the furnace where
they are withdrawn at the front end through a hinged or other door in the bridge
wall or divison.
Instead of bearing directly on the bridge or cross bar at the extreme front end
of the furnace the furnace bars may be supported on antifriction rollers on a bar
passing through them and bearing on the front bridge so as to reduce the friction
on the reciprocating bars.