MENTS IN ROTARY SCREENS
Year: 1885

page_text: I, WALTER WILLIAM BULLOCK, of 63 Woodhouse Street, Ipswich in the County
of Suffolk, plate worker, do hereby declare the nature of my invention for IMPROVE-
MENTS IN ROTARY SCREENS to be as follows:-
My improved screen consists of two cylinders made to slide longitudinally one
within the other, after the manner of a telescope tube.
Each of the cylinders is produced by coiling a narrow strip of thin plate, or a
wire with a flat face, spirally round a cylinder, so as to produce a screw of uniform
pitch, with the spaces between the separate coils of the strip or wire equal to the
width of the strip, or thereabout; but, preferably, the spaces should not exceed the
width of the strip or wire.
The separate coils of the strip or wire composing the cylinder are permanently
fixed in position by being soldered or otherwise attached to any convenient number
of strips of similar plate or wire (or it may he bars of suitable strength according
to the length of the screen) disposed at equal distances round the circumference of
the cylinder, and preferably parallel with the axis; the longitudinal strips or bars
of the inner cylinder being attached inside, and those of the outer cylinder outside
of the coiled strip or wire. Thus the coils of the inner cylinder will lie close
against those of the outer cylinder.
Two cylinders thus formed and having the coils of the strips or wires at the same
pitch are made to fit closely the one upon the other, but so as to admit of sliding'
longitudinally.
The inner cylinder is mounted upon a suitable number of heads with arms keyed
permanently in position on a spindle; but the outer cylinder is attached at one end
only to a similar head and set of arms, and this head is made to slide along the
spindle by a screw or other means.
The outer cylinder may thus be shifted along the inner cylinder so that the
spaces between the coils of the one may be completely closed up by the coils of the
other; intermediate positions thus give all grades of adjustment from the full size
of the spaces between the coils to nothing.
I find it convenient in practice to vary the width of the strip or wire of which
the coil is composed for a certain portion of the length of the cylinder, when it is
desirable to have a somewhat finer gauge near the head of the screen; as, for
instance, when screening large and small grain mixed with dust. The coils of the

page_text: spiral being at the same pitch throughout, the spaces where the coils are wider will
necessarily be narrower; and the difference of gauge so produced will remain
constant throughout the range of adjustment.
I have described my improved screen as composed of cylinders, but it is obvious
that similar screens may be made of a polygonal form. I have also described the
cylinders as being produced by a spirally coiled strip or wire, which is the mode of
manufacture I prefer, but it is also obvious that the same result may be produced
with cylinders composed of parallel rings instead of the continuous spiral coils.
My improved screens are mounted in a suitable stand with receptacles below to
receive the siftings in the usual way; the spindle turning in bearings and being
moved by a crankshaft and wheel gearing to give the requisite speed for hand or
other motive power.
The cylinders may be so mounted in an inclined position or horizontal; in the
latter case I find it convenient to fix a spiral plate or worm in the interior, for
conveying the grain along the screen to the delivery end.
To remove any adhering matters I prefer to fix a stationary brush externally at
some convenient point of the upper half of the screen.
I, WALTER WILLIAM BULLOCK of 63 Woodhouse Street, St. Clements Ipswich
in the County of Suffolk, plateworker, do hereby declare the nature of my inven-
tion for IMPROVEMENTS IN ROTARY SCREENS and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement
My improved Screen consists of two cylinders made to slide longitudinally one
within the other after the manner of a telescope tube.
Each of the cylinders is produced by coiling a narrow strip of thin plate spirally
round a cylinder so as to produce a screw of uniform pitch, with the spaces between
the separate coils of the strip equal to the width of the strip, or thereabout; but
preferably the spaces should not exceed the width of the strip. The separate coils
of the strip composing the cylinder are permanently fixed in position by being
soldered or otherwise attached to any convenient number of strips of similar plate
(or it may be bars) of suitable strength according to the length of the screen, dis-
posed at equal distances round the circumference of the cylinder, and preferably
parallel with the axis; the longitudinal strips or bars of the inner cylinder being
attached inside, and those of the outer cylinder outside of the coiled strip; thus the
coils of the inner cylinder will lie close against those of the outer cylinder.

page_text: Two cylinders thus formed and having the coils of the strips at the same pitch
are made to fit closely the one upon the other, but so as to admit of sliding longi-
tudinally.
The inner cylinder is mounted upon a suitable number of heads with arms and
keyed permanently in position on a spindle; but the outer cylinder is attached at
one end only to a similar head and set of arms, and this head is made to slide along
the spindle by a screw or other means. The outer cylinder may thus be shifted along
the inner cylinder so that the spaces between the coils of the one may be completely
closed up by the coils of the other; intermediate positions thus give all grades of
adjustment from the full size of the spaces between the coils to nothing.
I find it convenient in practice to vary the width of the strip, of which the coil
is composed, for a certain portion of the length of the cylinder when it is desirable
to have a somewhat finer gauge near the head of the screen; as for instance, when
screening large and small grain mixed with dust; the coils of the spiral being at
the same pitch throughout, the spaces where the coils are wider will necessarily be
narrower, and the difference of gauge so produced will remain constant throughout
the range of adjustment.
I have above described my improved screen as composed of cylinders, but
it is obvious that similar screens may be made of a polygonal form. I have also
described the cylinders as being prepared by a spirally coiled strip or flat wire,
which is the mode of manufacture prefer, but it is also obvious that the same
results may be produced with cylinders of parallel rings instead of the continuous
spiral coils.
My improved screens are mounted on a suitable stand with receptacles below to
receive the siftings in the usual way; the spindle turning in bearings and being
moved by crank handle and wheel gearing to give the requisite speed for hand or
other motive power. The cylinders may be mounted in an inclined position or
horizontal; in the latter case I find it convenient to fix a spiral plate or worm in
the interior for conveying the corn along the screen to the delivery end.
To remove any adhering matter I prefer to fix a stationary brush externally at
some convenient point of the upper half of the screen.
And in order that my invention may be clearly understood, I will now describe
the drawings annexed hereto.
Fig. 1. is a side elevation, partly in section, of a cylinder for a rotary screen,
constructed in accordance with my invention.
Fig. 2. is an end view of the same.
Fig. 3. is a full-size view of a portion of the screen shewing the spaces between
the coils or rings wide open.
Fig. 4. is also a full-size view of a portion of the screen, but with the spaces
between the coils or rings of the one cylinder completely closed by the coils or rings
of the other.
Fig. 5. is a portion of the internal spiral plate or worm to be used when the
cylinders are to be mounted horizontally.
The same letters indicate the same parts in all the figures.
A, is the spindle upon which the screen is mounted, and which turns in bearings
upon a suitable stand, (but this and other parts not essential to the invention are
omitted); it is shewn hollow as being preferable for lightness and stiffness in long
screens, but this is not necessary; b, b', are two heads with arins c, c', and bosses
d, d, which are permanently keyed upon the spindle; to these two heads the inner
cylinder is permanently attached; in screens of larger size more of these heads
would be employed, but for screens of ordinary size the two will be sufficient; e, is
the head to which the outer cylinder is attached, the arms f, connect it with the
boss g, which is caused to slide along the spindle by the screw h, and crank i, and
carries the outer cylinder with it; j, j, are the separate coils or rings of the inner
cylinder, and k, k, those of the outer cylinder; shewn in fig. 3. in position one upon
the other leaving the spaces between the coils or rings wide open for the passage of
the screenings, and in fig. 4 with the openings quite closed up so that nothing can

page_text: .
pass through. In fig. 3. the coils or rings x, x, are shewn rather wider than the
rest, and consequently the spaces between those coils or rings are by the same
amount narrower than the rest; l, is the spiral worm to be employed when required,
for instance, when it is desirable to place the screen horizontally; m, is a stationary
brush, fixed to some convenient part of the frame so as to act externally against
some point of the upper half of the screen.
Although I have shewn in the drawings a cylinder for my improved rotary
screens in which the coils or rings are formed of strips of plate or flat wire, I would
have it understood that I do not limit myself to any particular section for such
coils or rings, as they might obviously be of a triangular or semicircular or of any
section having a flat face suitable for making one cylinder to slide upon the other.
Neither do I limit myself to the cylindrical form of screen shewn, as in some cases
I find it preferable to give the body of the screen a polygonal form; the mode of
construction being the same in either case.
Likewise, when my improved rotary screens have the cylindrical form and the
cylinders are composed of spiral coils, I prefer to effect the adjustment of the spaces
"between the coils by sliding one cylinder upon the other longitudinally, but I may
also effect the adjustment by partially rotating the one cylinder upon the other;
I therefore do not confine myself to the longitudinal movement 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. The construction of cylindrical or polygonal rotary adjustable screens substan-
tially in the manner described.
2. Obtaining a more efficient range of adjustment in rotary screens by forming
one cylinder or polygonal prism to slide upon another longitudinally, such cylinders
or prisms being composed of helical coils or parallel rings of strips of plate or wires
of any suitable section.
3. In cylinders for rotary screens, composed of helical coils as above described,
effecting the adjustment by partially rotating one cylinder upon the other.
4. Obtaining variations in the gauge of the spaces between the coils or rings, for
different portions of the length of the screen, by varying the width of the strips or
wires of which the coils or rings are composed.
Dated this 23rd day of September 1885.

page_text: FIC. I.