IMPROVEMENTS IN OR RELATING TO SCREENS FOR SIFTING AND FOR LIKE PURPOSES
Year: 1885

page_text: like Purposes.
I EDWARD LYALL of Walsall Wood Colliery, near Walsall Mining Engineer
do hereby declare the nature of the said invention for "IMPROVEMENTS IN OR
RELATING TO SCREENS FOR SIFTING AND FOR LIKE PURPOSES" to be as follows:-
These screens are constructed much in the usual manner but may be much
smaller than the ordinary ones and disposed in a nearly horizontal plane.
A quick horizontal motion from side to side is imparted to the screen in any
suitable manner so that the coal works down it in a zig zag fashion at a speed
which may be varied according to the inclination of the screen.
I find that by this arrangement the coal becomes more perfectly separated than
by the usual means.

page_text: like Purposes.
I EDWARD LYALL of Walsall Wood Colliery Walsall, do hereby declare the
nature of my invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :—
In the accompanying Drawings Figure 1 is a vertical section from front to back;
Figure 2 is a front elevation with back plate removed and Figure 3 is a plan.
The apparatus consists of an iron frame shut in at the sides with iron plating K
and slung at or near the four corners by rods or chains L in such a manner that it
may be swung freely to and fro in a direction at right angles to that in which
the material to be screened passes down it.
This motion is given to it by means of a cranked shaft M and connecting rods N
worked by a small engine or other suitable power. The stroke requires to be short
but quick.
The sieves are arranged in the manner shown in Figure 1. The material to be
screened is tipped on to the sieve A down which it is caused to move by the slight
incline and the side to side motion of the screen the portion which does not pass
through the meshes of the sieve passing out at the shoot F.
That which falls through the meshes of the sieve is caught on the plate D and
conveyed to the upper end of the second sieve B over which it moves in a similar
way and out at the shoot G. So also with the third sieve Cover which the stuff
passes and out at H the quite fine dust falling direct into the wagon below.
These sieves are all placed at such an angle that the material to be screened will
not roll or slide down of itself.
Six inches swing from side to side is generally best at about the rate of
200 strokes per minute but of course this and the inclination of the sieves depend
greatly on the material to be dealt with.
The principal advantages of these screens are as follows:―
They are cheaper than most of the other sorts at present used.
They require much less height in proportion to the number of sizes turned out.
They separate the material much more perfectly than the usual sorts of screens.
They require no hand labour.
Through the very quick smooth motion from side to side the coal etc is caused
to flow down almost like water the screen moving from under the stuff, not
knocking it violently from side to side as at first sight might be expected, in fact
the sides are hardly ever struck by the material on the sieves.
They turn out more stuff in a given time than ordinary screens.
It is particularly adapted to collieries when the coal has to be hand picked for
by placing iron shoots at such an angle that the coal will just remain still upon
them, the slight impetus given to it as it leaves the screen causes it to slide slowly
down before the eyes of the pickers on its way into the wagons.

page_text: 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. In an apparatus such as described a sieve or series of sieves reciprocating in a
direction at right angles to the path of the material being screened substantially as
specified.
2. The method of screening coal and the like by imparting a smooth and rapid
reciprocating motion to a screen set on a slight incline said motion being in a
direction at right angles to the path of the material being screened.