IMPROVEMENTS IN STEAM BOILER FURNACES FOR ECONOMISING FUEL AND CONSUMING SMOKE
Year: 1870

page_text: PROVISIONAL SPECIFICATION left by John McNaught and William
McNaught at the Office of the Commissioners of Patents, with their
Petition, on the 6th April 1870.
We, JoHN MCNAUGHT and WILLIAM MCNAUGHT, junior, of St.
George's Foundry, Rochdale, in the County of Lancaster, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN STEAM
BOILER FURNACES FOR ECONOMISING FUEL AND CONSUMING SMOKE," to be as
follows:-
Our improvements relate to that class of furnaces having link fire-
bars connected together to form a broad endless chain surface, and
our improvements consist mainly in the combination, arrangement, and
construction of the parts of the machine, whereby we are enabled to
apply this class of furnace with great facility and advantage to internal
flued steam boilers, and to give a wider fire-grate surface, larger ash
space, and better access for air than has hitherto been obtained by
previous arrangements in the same width of flue, and at the same time
we reduce the wear and tear and the strain and friction to such extent
that very little power and but simple driving gear is required to give
motion to the machine. We form the grate bars of short links jointed
on rods passing across the furnace, these rods being without heads

page_text: or cottars, as they and the links are kept in their places by the side
frames of the machine. These endless chain fire-bars pass over rollers
at each end of the machine, the roller at the interior end of the machine
being of much smaller diameter than that at the exterior end, which
latter is provided with adjusting screws to regulate the axis of the
roller so as to adjust the tension of the bars. The bars when carrying
the fuel along are supported at intervals on hollow rollers which rotate
on stays passing across between the side frames, and the bars in
returning are supported on similar rollers in a lino parallel to that
surface of the bars carrying the fuel, but after leaving the entrance to
the flue the chains pass over a guide pulley at cach side, and descend
at an inclination so as to pass under the large roller at the exterior end
of the machine. The side links fit teeth on the exterior roller by which
motion is given to the grate bars, the' motion being transmitted by a
worm and worm wheel rotated by any suitably gearing. At the interior
end of the machine there is a hollow box acting as a fire bridge and
a scraper to prevent the fuel from being carried too far, and this hollow
box is connected by pipes with the water space of the boiler so that it
is kept cool. A jet of steam is also employed to play against the fire-
bars near the bridge to keep them cool and assist combustion. The
fire-bars at the front of the machine before entering the flues are enclosed
by an arch of fire-brick. The fuel is placed upon a surface or incline
in front, the thickness of the layer of fuel being regulated by a slide
lined with fire-brick which is moved vertically by a shaft, and racks
and pinions, or by other suitable means. An inclined trough may be
used to catch the ashes, and motion may be given to this trough to
discharge the ashes in front, or a screw having a slow motion imparted
to it may be used for this purpose. A central wheel is connected with
interior end of the frame, and two side wheels are arranged at the
front end which give facility for withdrawing the whole machine from
the boiler flue when required.