Improvements in Mechanical Stokers for Boiler Furnaces.
Year: 1898

page_text: Date of Application, 7th July, 1898-Accepted, 22nd Oct., 1898
COMPLETE SPECIFICATION.
Improvements in Mechanical Stokers for Boiler Furnaces.
We, FRIEDRICH EMIL HOFMANN, Mill Owner, of Geringswalde, and FRIEDRICH
HERMANN HOFMANN, Mill Owner, of Schonberg, near Waldheim, both in the
Empire of Germany, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement:—
This invention for improvements in mechanical stokers for boiler furnaces
relates to a special arrangement for filling and operating the shovel in apparatus
with automatic stoking contrivances for heating boilers.
The distinguishing feature of the invention is that the shovel is first uniformly
filled on its entire surface, and then, being rotated throws the coal beyond the
point of rotation so that the coal flies off from the shovel at different radii of rota-
tion, and is thus cast to different distances and quite uniformly distributed over
the fire.
In the accompanying sheet of illustrative drawings:
Fig. 1 is a front view of a mechanical stoker constructed according to this
invention.
Fig. 2 a sectional elevation of the same the shovel being shown full of fuel.
Fig. 3 is an elevation of the mechanism for effecting motion.
Fig. 4 is a sectional elevation showing the position of the parts when the fuel
is thrown out of the shovel.
Fig. 5 the position of the mechanism during the discharge.
Figs. 6 and 7 are similar views in connection with the backward or return
movement of the shovel.
The shovel A is applied to a stoking apparatus over the fire door in front of the
fire-place (see Figs. 1, 2 and 4); it is fixed on the shaft which is set in motion
by the wheel c, the shovel when turned over being limited in its movement by
adjustable projections & Fig. 4.
The coal is conveyed to the shovel A by means of a trap 33 which, in consequence
of an oscillating motion, see Figs. 2, 4 and 6, suitably distributes the coal over
the surface of the shovel.
The coal is supplied to the trap B by means of a roller or cylinder D the
circumference of which is partially furnished with cells or compartments f f¹
which, when the cylinder D is rotated in the mill hopper are filled with coal
through the apertures g therein, which is discharged on to the trap by means of
apertures h.
Above the cylinder D is a spoked cylinder, the spokes
purpose of a uniform feeding of the fuel, engage or take hold
there crushing small pieces and throwing larger ones out
flap see Fig. 4.
of which, for the
through the bars k,
through the spring
The combined action of the parts is effected as follows:-From the shaft m of
the cylinder D, which shaft is operated in any manner, the spoked cylinder is
driven by means of suitable transmission gearing. The trap B is actuated by an

page_text: eccentric mounted on the shaft m, and on the circumference of the eccentric r
a lever constantly slides, the said lever being firmly fixed to or forming part of
the oscillating shaft n of the trap, whereby the trap is brought into suitable
guiding position. Further on the shaft m is a spiral eccentrics on the circum-
ference of which a double lever t t slides with its bent end, its other end being
furnished with a toothed segment which drives the wheel c on the shaft of the
shovel and against which wheel a suitably strong spring acts contrary to the
pressure of the spiral.
Whilst the levert runs down the spiral, the shovel A is gradually brought from
its discharging position into its re-filling position, see respectively Fig. 4 and
Fig. 6 and Fig. 2 the trap B actuated by the eccentric being moved gradually
backwards and distributes the contents of the cells or compartiments f f f which
appear one after the other before the aperture h uniformly over the shovel.
When the cylinder D is further rotated, whereby the lever t recedes from the
highest position of the spiral to the lowest, the spring throws the segment for-
ward (that is to say there is a rapid upward movement of the shovel), the charge
in the shovel consisting of coal or other material being cast of properly or regularly
when the shovel strikes the projections d so that it is uniformly distributed over
the bars.
According to the heaviness of the material and the distance it is thrown, the
throwing off position of the shovel is determined by putting the projections d
forwards or backwards-in any case however the coal is thrown off in a proper
and effective manner.
The stoking apparatus can be applied singly or manifold according to the
number of the fires with simultaneous or successive throwings out of the coal
according as the cylinders D are placed in relation to one another and may be
used in all suitable kinds of fire places.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. A mechanical stoking apparatus the distinguishing feature of which is that,
for the uniform charging of the shovel, which rotates around the shaft b, a
cylinder 1 partially furnished on its circumference with cells or compartments f
fifa and rotating in the mill-hopper first conveys the fuel to a trap B lying over A
and set in oscillating motion by means of an eccentric r and lever p, and that then
the spring which is distended from the shaft m of the cylinder D by means of
the eccentric disc and levert draws back quickly the lever t connected with the
shovel A and thereby causes the shovel A to strew the fuel over the bars.
2. The improved construction of mechanical stokers for boiler furnaces sub-
stantially as described with reference to the drawings.
Dated this 7th day of July 1898.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.