IMPROVEMENTS IN COAL AND OTHER SCREENS, WHICH IS ALSO APPLICABLE TO OTHER PURPOSES."
Year: 1880

page_text: LETTERS PATENT to Christopher Armstrong, of London, in the County of
Middlesex, for an Invention of "IMPROVEMENTS IN COAL AND OTHER SCREENS,
WHICH IS ALSO APPLICABLE TO OTHER PURPOSES."
PROVISIONAL SPECIFICATION left by the said Christopher Armstrong at
the Office of the Commissioners of Patents on the 19th January 1880.
CHRISTOPHER ARMSTRONG, of London, in the County of Middlesex. "IMPROVE-
MENTS IN COAL AND OTHER SCREENS, WHICH IS ALSO APPLICABLE TO OTHER
PURPOSES."
My Invention has reference to improvements in coal and other screens, which is
also applicable to other purposes, such as the fire grates of boilers, sewer grates, and
other such like purposes.
I will explain my Invention as applied to a coal screen such as those used in the
coal bays at the London depots.
The bars from which my screens are made, i.e., the bars over which the coal or
other material passes are in sectional shape, an exact equilateral triangle, and
therefore all the sides of the bars are equal in width. By this shape I not only
produce a bar which may very easily be rolled in long lengths from steel, iron, or
other metal, but they are reversible, that is to say, I can wear all the three sides by
turning each side of the bars uppermost in turn. There is a still further advantage,
viz., in putting my screens together I use two sides or a frame made of either iron,
wood, or other suitable material, in which I form notches or holes, also an exact
equilateral triangle in shape, so as to exactly correspond with the rolled or cast bars
forming the screens.
By this means I obtain a most effective screen which will last much longer than
the ordinary ones and it will do its work cleaner, and I obtain the very desirable
end of being able to interchange every bar in a most complete manner.
For boiler grates the bars would be used in much the same manner, i.e., separately
to fit in the bearers of the boiler or other grate, or fastened together in sections.
The sewer grates would be the same as regards the section of the bars, but they
may be cast if necessary, as may also the preceding ones when desired.
These bars may also be applied to ordinary fire-places and kitchen ranges.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Christopher Armstrong in. the Great Seal Patent Office on the 17th
July 1880.
CHRISTOPHER ARMSTRONG, of London, in the County of Middlesex. " IMPROVE-
MENTS IN COAL AND OTHER SCREENS, WHICH IS ALSO APPLICABLE TO OTHER
PURPOSES."
My Invention has reference to improvements in coal and other screens, which is
also applicable to other purposes, such as the fire grates of boilers, sewer grates,
and other such like purposes where there is a difficulty in keeping the spaces clear
from choking...
The principal defect in the screens hitherto in use has been the almost insuperable
difficulty of keeping them free from choking, especially in wet weather, consequently
at a time when it is most desirable they should act efficiently, they become
(practically) almost useless.
To remedy this evil (as far as possible) the old screens have been constructed
with the bars so far apart that in the attempt to separate the slack or dead small
effectually from the large coal a heavy per centage of good sound nutty coal passes
through the bars, which must either be disposed of as small at an inferior price or
screened over again (at increased cost) to enhance its value.
I will explain my Invention first of all as applied to a coal screen such as those
used in the coal bays a' the London depots.
Figure 1 is a longi dinal sectional elevation of part of a coal screen, and
Figure 2 is a plan of the same. The bars from which my screens are made, i.e., the
bars over which the coal or other material passes are in sectional shape, an exact
equilateral triangle, and therefore all the sides are equally suitable to be upwards,
and they may therefore be reversed with the greatest facility, and they can be
rolled most easily, as the bar can be turned round in the rolling either side going in
uppermost. The facility with which my bars may be reversed will be apparent
on reference to the frame A, A, A, into which the steel or other bars B, B, B, B,
drop, suitable recesses being provided in the sides of the frame. The bars may thus
be turned over as often as necessary which multiplies the life of the screen many
times. There is also another advantage, that by turning the bars end for end I am
able to present a sharp edge to the coal as it runs down, which is really the
desideratum in screening wet coal as it cleans off the fine dust perfectly without
having the bars of the screen too open or far apart. I can therefore separate the
finest dust from coal more perfectly than has been hitherto done with less loss in
waste for the reason hereinbefore explained. The frame A, A, A, may be either
cast, or the sides may be wrought iron, wood, or other suitable material, so long as
they are provided with suitable means for reversing the bars. If desired, these
grates may be made of solid cast iron or other metal as they would be the very
easiest grate to mould, but I prefer to use steel bars.
A modification of a coal screen is shown by Figure 3 in cross section where
provision is provided in the side marked C for the bars D to enter the holes, and
the other end drops into recesses in the E side where they are held down by a
suitable cover plate F by bolts, or in any other convenient manner according to the
requirements of the position where the screen is to be fixed and the nature of the
work to be done.
The screens described are such as would be applied to such places as the coal bays
of the London depots, but I also make a portable screen for use along sidings in
unloading trucks. Much difficulty is now experienced in getting the coal, which is
loaded direct from the trucks, properly screened, because it is naturally a very slow
process to pass each shovel full of coal through a hand riddle, and an extra man to
each gang is usually required in such cases. I meet these difficulties by arranging

page_text: my portable screens so as to stand about the height or a little above the side of a
coal truck; the top is formed of a hopper shape to receive the coal, and it runs down
over the screen and through a suitably formed mouth piece into the coal bag which
stands on the scales ready to receive it very similar to the mouth of an ordinary
coal bag. These screens may be moved on wheels or carried about. A considerable
saving will thus be effected in labour and the work will be more certainly
performed.
Figure 4 is a sectional elevation, and Figure 5 is a plan of a grate suitable for
sewers. The bars H are rolled, cut off, and roughed at the ends and laid in a
mould, and the metal forming the side J, J, J, J, is cast around their ends to form
the frame.
For boiler grates and other similar positions the bars would be used either in
Bingle bars laid in a frame or fastened into sections of any convenient number of
bars according to the position and requirements of each special case.
Having now described the nature of my said Invention of improvements in coal
and other screens, which is also applicable to other purposes, I would have it clearly
understood that I do not bind myself to the particular cases mentioned, as my
equilateral bars will be found applicable to many other purposes not mentioned
herein, but what I do claim as my Invention is,—
The construction of coal screens, sewer grates, fire grates, and other grates,
and similar articles from bars of equilateral section, and as herein described and
illustrated.
In witness whereof, I, the said Christopher Armstrong, have hereunto set
my hand and seal, this Thirteenth day of July, in the year of our Lord
One thousand eight hundred and eighty.
CHRISTOPHER ARMSTRONG. (L.S.)