Improvements in Balanced Screens.
Year: 1889

page_text: Date of Application, 1st Feb., 1889
Complete Specification Left, 4th June, 1889-Accepted, 13th July, 1889
Improvements in Balanced Screens.
I JAMES RIGG of Number Eleven Queen Victoria Street in the City of London,
Mechanical Engineer do hereby declare the nature of this invention to be as
follows:-
Improvements in the manner of controlling the operation of balanced curved or
other moving screens used for separating into different sizes coal or other minerals or
materials and in the manner of regulating their delivery as described hereafter.
The Screen is so constructed as to be capable of oscillating to any desired extent
upon an axis and is so carried that when empty and uncontrolled a preponderating
weight raises it to its normal position for the reception of the mineral to be screened,
which, being delivered upon it from a tram, tub, corve or other receptacle overcomes
this preponderance and causes "the screen to sink into a position or angle permitting
of the mineral passing by gravitation into the truck, boat or other place prepared for
its reception.
The first portion of this Invention relates to the manner of controlling the movement
of the screen and this I do by placing in a convenient position, and proferably, above
the screen, a cylinder or cataract chamber for water or other suitable fluid. Å Piston
within this "cataract" is attached by chains, connecting rods or other method to the
body of the Screen and in a pipe connecting the water or other fluid at the top with
that at the bottom of the cataract I place a valve or tap, the regulation of which by
the person in charge of the screen enables him readily to control its movement this
being caused in both directions by the force of gravity.
The second portion of this invention consists of a lip or door placed at the lower
end of balanced screens, for the purpose of preventing the coal or other material from
passing over the end of the screen both when being filled and during its descent until
it arrives at such position as may be desired. The lip or door is hinged and held in
position by a latch or latches, these being released automatically at the desired point
and remaining open as long as the coal is being discharged, when it is closed by means
of a balance weight or weights and is again in the fixed position preventing the coal
or other material from passing accidentally into the truck or boat.
Dated this First day of February 1889.
COMPLETE SPECIFICATION.
Improvements in Balanced Screens.
1, JAMES RIGG of number eleven Queen Victoria Street in the City of London,
Mechanical Engineer do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
The screen to which this Invention is applied may be constructed as shewn in Fig. 1
sheet 1 and Fig. 2 sheet 2 the angle of oscillation being here limited to the arc M N
having for its centre the axis X. The screen appears empty and in the position
for receiving coal the preponderating weight at Y bringing it to the normal state of
rest.
Coal being received upon the upper end of this screen passes by gravity to a point
beyond the axis of oscillation X and to control the preponderance which is thus trans-
ferred to the lower end of the screen I place a cataract chamber or cylinder P
containing water or other fluid and a piston communicating with a crosshead H which is
attached to the body of the screen either by flexible chains R Q shewn in Figs. 1 & 2

page_text: or rigid connecting rods. This connection may be made to either the upper or lower
end of the screen but I prefer the latter. A tap L on the pipe K enables a com-
munication to be established between the water above and that below the cataract
piston and the regulation of this tap controls alike the normal preponderance at the
upper end of the empty screen or that which may exist at the lower end when the
screen contains coal or other mineral at this part. The cataract cylinder is supplied
from a tank by means of the pipe J.
The second portion of this Invention consists of a hinged lip or door T which may
be attached to the lower end of curved or other balanced or moving screens as shewn
at U. The object of this door or lip is to prevent the coal or other material from
prematurely passing away either before the operation of screening is complate or
previous to the commencement of the screen to descend. During the descent of the
screen the latch Z is automatically released and after the coal or other mineral is
discharged the lip or door automatically closes consequent on the operation of a
weight attached to the chain O. The screen being now empty the valve L is again
opened thus reestablishing communication between the upper and lower ends of tho
cataract cylinder P and the counterbalance at Y causes its return to the normal
position ready to receive another load.
Having now particularly described and ascertained the nature of my said Inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The method of controlling the movement of a balanced screen in both directions
by means of a cataract generally as described. and connected to the screen body by
means of chains or by connecting rods or by a combination of both.
2. The automatic closing and opening of the lip or door at the delivery end of
moving screens generally as described and illustrated.
Dated this Fourth day of June 1889.
JAMES RIGG.