IMPROVEMENTS IN FURNACES FOR HEATING STEAM BOILERS AND FOR SIMILAR PURPOSES
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by William Robert Lake at the Office of
the Commissioners of Patents on the 8th July 1878. A communication from
abroad by John Ashcroft, of Brooklyn, New York, United States of America.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN FURNACES FOR HEATING
STEAM BOILERS AND FOR SIMILAR PURPOSES." [A communication from abroad by
John Ashcroft, of Brooklyn, New York, United States of America.]
The said Invention relates chiefly to the novel construction of the doors and
grates of furnaces for steam boilers, whereby smoke is prevented, fuel is economized,
and other advantages are obtained.
In carrying the said Invention into practice I provide within the frame of the
door, which is hung on hinges in the usual manner, a swinging door hung hori-
zontally and centrally, so that the bottom may swing inwardly or outwardly as
may be desired. This door being hung centrally, requires no counterpoise or weight
to keep the same in any desired position..
The door is forined of two curved plates connected by two side plates, a space
being left between the plates for admission of air into the furnace. The top of this
swing door is made thicker than the bottom, but is partially covered, leaving the
aperture for the air near the outer plate. The plates curve inwardly at the bottom
to give the required direction to the air, and the inner plate curves inwardly at the
top. The air. passes into the furnace through the space between the plates when
the door is in its normal position.
When it is desired to prevent the ingress of air, the top of the swing door can be
pushed inward, when the frame will cover the space.
The top of the door should be made convex to prevent the admission of air
between the top of the door and the frame when the door is rotated. A flange
cast upon the frame surrounds the swing door, the outer edge of the flange
corresponding with the contour of the outer plate of the door.
When more air is required in the furnace, the bottom of the door is swung
inwardly. The air that enters between the plates passes under the inner plate,

page_text: which is somewhat shorter than the outer one, and is thereby reflected upon the
burning fuel. The curvature of the plates is designed to give the proper direction
to the air, whatever the position of the door.
The grate bars are made to rotate or revolve independently without changing
their relative positions; they are plain three-sided bars. The sides are convex and
rounded at their intersections. The bearings for these bars are circular grooves or
holes formed across the bearing bars.
"
The front bearings may advantageously be circular holes, the rear ones circular
recesses, and the intermediate ones semicircular grooves.
The form of the bars and the bearings may be modified, but the relative shape
should be such that the bars may be readily revolved or rotated without change in
the relative positions of the bars, and spaces be left between the bars and the
bearings to admit air. These plain bars extending the length of the furnace may
be readily removed and conveniently rotated.