IM- PROVEMENTS IN APPARATUS APPLICABLE TO THE FURNACES OF PORTABLE AGRI- CULTURAL & OTHER STEAM ENGINES REQUIRED FOR BURNING STRAW AND OTHER LIGHT VEGETABLE MATTERS
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by James Marshall at the Office
of the Commissioners of Patents, with his Petition, on the 4th
February 1874.
I, JAMES MARSHALL, of Gainsborough, in the County of Lincoln,
Engineer, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN APPARATUS APPLICABLE TO THE FURNACES OF PORTABLE AGRI-
CULTURAL & OTHER STEAM ENGINES REQUIRED FOR BURNING STRAW AND OTHER
LIGHT VEGETABLE MATTERS," to be as follows:-
For this purpose, according to one part of my improvement, I apply a
tube of any suitable section to the fire hole of an ordinary locomotive
multitubular boiler of sufficient length to admit the introduction of con-
tinuous charges of straw or other like fuel in such a manner that
during the process of feeding a charge or plug of such fuel (of sufficient
density to prevent the admission of an undue amount of cold air to the
fire-box) shall always be contained therein, each charge pushing before
it the preceding one, and taking its place as a plug to the tube until in
its turn pushed forward by the subsequent charge, by this means keeping
the feed aperture constantly closed. This feed tube is connected to the
fire-box front by a hinge or hinges to admit of its being turned aside or.

page_text: lowered in front when the feeding is suspended; when the tube is so
turned aside or lowered the ordinary fire door (which is retained) closes
the opening into the fire-box.
On the top of the feed tube near the fire-hole is an aperture with a
hinged door opening downwards into the feed tube by means of a lever,
which will admit of the fire being inspected from time to time, and a
poker used when occasion requires.
The grate or furnace bars according to my improvements are cast in
pairs, and dished or sunk downwards from their bearing so as to bring
the greater part of the surface of the grate below the fire-box bottom, to
render the upper surface of the bars on which the fuel rests more
accessible, for the purpose of removing any accumulation of slag which
may form thereon.
According to another part of my improvements I apply in combination
with a similar feed tube to that above described a worm attached to a
horizontal spindle, to which, is given a rotary motion by or in connection
with the engine, which worm acting upon the surface of the straw or
other fuel in the tube presses it forward into the fire-box.
Similar appliance to those previously described for attachment to the
fire-box and for facilitating stoking are applied in connection with this
part of my improvements.
- According to another part of my improvements I attach a feed box
to the lower part of the fire-box front, on which is placed a mechanical
feed appliance consisting of a revolving barrel having inserted on the
periphery thereof a series of prongs, and forming combinedly a revolving
fork, which as it revolves forks the fuel from the hopper and pushes it
forward upon the fire-grate.
To prevent the straw lapping round the barrel or being carried back
into the feed hopper, a plate slitted for the prongs to pass through is
made to touch the surface of the barrel, which liberates the straw and
directs its passage forward to the fire-grate.
In connection with this part of my improvements the dished fire-bars
such as previously described, are employed, having the sides of those
immediately opposite the feeding aperture removed to admit the passage
of the fuel. The ends of those bars rest on an angle iron bearing
attached to the ash
pan.

page_text: A portion of the lower part of the feed box is hung on a hinge, and is
let down to admit of the raking of the fire when required, and a door
opening upwards at the junction with the grate bars closes the connection
between the feed box and furnace.
According to another part of my improvements I attach as herein-
before described a feed box to the lower part of fire-box front, but
instead of the revolving barrel with prongs I introduce a mechanical
feeding appliance, consisting of a series of prongs attached to a spindle,
to which a rocking or reciprocating motion is given from the engine
through the crank at the end of said spindle.
By the reciprocating motion of the prongs the fuel is drawn from the
feed hopper and pushed forward to the fire-grate. An elastic plate fixed
to the bottom of the hopper prevents the return of the fuel after passing
this point.
The doors for facilitating the raking of the fire above the bars, and for
closing the connection between the feed box and furnace are similar to
the arrangements herein-before described.