IMPROVEMENTS IN APPARATUS FOR SCREENING OR SIFTING AND CLASSIFYING MINERALS
Year: 1885

page_text: I, WALLACE FAIRWEATHER, of 96 Buchanan Street, Glasgow, in the county of
Lanark, Fellow of the Institute of Patent Agents, do hereby declare the nature
of my invention for "IMPROVEMENTS IN APPARATUS FOR SCREENING OR SIFTING
AND CLASSIFYING MINERALS," (a communication from Johann Karlik, of Kladno,
Bohemia, in the Austrian empire, Engineer) and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
The various kinds of apparatus commonly employed for screening and classifying
coals or other minerals-with the exception of the drum which occupies much
space are operated by eccentrics or have a jigging or vibratory movement
imparted to them, but as the masses in movement are generally very considerable,
such sifting apparatus is within a short time rendered unserviceable in consequence
of the shocks and strains to which the parts are subjected.
In order to obviate these disadvantages, the screens of the apparatus which forms
the subject of this invention are supported by a frame disposed symmetrically
round a straight line passing through its centre of gravity, and at the one or at
the other of the extremities of this line the frame is suspended or supported by
means of an universal joint, so that this frame can turn, in the fashion of a conic
pendulum, round the imaginary vertical line passing through the said joint. In
order to impart this movement to it a crank acts upon the other extremity of the
straight line or axis of symmetry passing through the centre of gravity of the
frame, this crank being upon a vertical rotating shaft located perpendicularly
below the universal joint. In order to binder the frame from turning round its
symmetrical axis during this movement, a guide bar or connecting rod is connected
at one extremity to this frame, whilst its other extremity is movable in a guide
supported by a universal joint.
In the accompanying Drawings Figures 1 and 2 represent, in elevation and in
plan, a rotatory and oscillating screen, of the kind described suspended by its upper
extremity. Figure 3 is an elevation of a suspended screen whose connecting-rod is
attached below the screens being one above another. Figure 4 shows a suspended

page_text: screen, whose connecting-rod, connected above the screens, forms at the same time
a guiding shoot or conduit whose inclination may be regulated. Figure 5
represents in lateral elevation a rotatory and oscillating screen supported by its
lower extremity and having a connecting-rod of the same construction as is shown
in Figure 4.
In each case the frame A of the screen, which is made of angle or sheet iron or
of wood, is disposed symmetrically round a straight line passing through its centre
of gravity, the frame being of conical, cylindrical, prismatic, or pyramidal form or
being formed of superposed sections of the enumerated forms. The extremity of
the top or of the bottom of the frame decreases in diameter to a point, and this
point is suspended or supported by means of an universal joint B. The other
extremity of the symmetrical axis of the frame serves as point of application for a
short crank C whose vertical shaft turns perpendicularly below the joint B in a
suitable bearing. As during the movements of a conic pendulum, which the frame
assumes, the basis of the latter places itself successively in planes of different
inclinations, it is necessary that the connection between the crank pin and the
base of the frame should be formed by a ball and socket joint or other universal
joint. The shaft of the crank C is driven by a pulley and belt from a counter
shaft.
The exterior extremity of the connecting-rod D which prevents the rotation of
the frame round its symmetrical axis, slides into the grooved pulley d, having its
bearings in a fork whose rod is free to turn on its axis. The inner end of this
connecting rod is attached to the frame by a bolt placed perpendicularly at the
symmetrical axis, so that the connecting-rod can oscillate in the plane containing
the connecting rod itself and the symmetrical axis of the frame A. In order to
make the connecting-rod D more solid and to guide with more certainty the
frame A, the connecting rod is bifurcated, as is represented in the drawings, and
the two arms of the fork which are joined together by draw rods, turn round bolts
placed in the same line perpendicular upon the symmetrical axis of the frame.
The screens, which are placed above one another between the uprights of the
frame, have meshes or perforations whose diameter decreases gradually from the
uppermost to the lowest of the series of screens, and in order that different lots,
each one composed of fragments of approximately equal size, may be thrown on
different points, these screens have different inclinations towards the symmetrical
axis of the frame.
In the screen represented by Figure 3, the connecting rod is connected at the
lower part of the frame. In this case the screen a at the top must extend far
enough in the direction of the hopper E, so that in all the positions into which
the frame A can be placed this screen is below the hopper. In figures 4 and 5 the
connecting-rod D, connected as high as the top screen, holds between its arms an
inclined shoot d¹. By means of the screw d³, Figure 4, it is possible to lift the
grooved pulley d, and in that way increase or diminish the inclination of the
shoot d', which accelerates or slackens the passing of the substance to be sieved.
From the foregoing, it will be easily understood that in all the screens a, the
meeting points of the symmetrical axis must describe circles contained in horizontal
planes, whilst all the other points of these screens describe ellipses ascending or
descending alternately. In consequence the movements of the screens imitate those
of a sieve worked by the hand.
Owing to the point of application of the crank being placed at the extremity of
a line passing through the centre of gravity of the whole apparatus very little
power is required to effect the sieving with the screen described.
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. As means for screening and separating or classifying mineral substances
composed of fragments of different sizes an annaratus consisting of a series of

page_text: superposed screens whose meshes are graduated and are smaller in the lower than
in the upper screens of the series, the whole being moved like a conic pendulum,
without being able to turn on their centres, substantially as set forth.
2. A screening apparatus for separating mineral substances in the manner
described, which is composed of a frame, supporting any number of superposed
screens arranged symmetrically round a straight line passing through its centre of
gravity, this frame being suspended or supported at the end of this axis of
symmetry by an universal joint and turned by a crank, and being connected to the
other end of the symmetrical axis round the perpendicular of the said joint like a
conic pendulum, whilst a connecting rod attached to the frame and guided by an
universal joint, prevents the rotation of the frame round its symmetrical axis.
3. In screening apparatus of the construction described, the arrangement of
separating screens inclined towards different points which has for its object to
throw the fragments of each size on a distinct place.
4. In screening apparatus of the construction described the arrangement of a
bifurcated connecting rod connected thereto as high as the top screen, and having
between its arnis an inclined shoot substantially as and for the purpose set forth.
5. In screening apparatus of the construction described a connecting rod, whose
exterior extremity can be raised or lowered, which has for object to increase or to
diminish the inclination of the shoot, and to accelerate or to slacken the introduction
of the matters to be separated substantially as set forth.
6. The combination of parts forming the improved screening apparatus herein
described and illustrated.