An Improved Device for Keeping Sieves Clear and Open.
Year: 1897

page_text: Date of Application, 26th Feb., 1897-Accepted. 10th Apr., 1897
COMPLETE SPECIFICATION
An Improved Device for Keeping Sieves Clear and Open.
I, FRIEDRICH BRANDSTAEDTER, of 15 Rue des Pénitentes, Louvain in the
Kingdom of Belgium, Mill Manager, 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:-
As is well known the meshes of sieves employed in milling easily become choked
with the flour. In order to prevent this, experiments have been made by yieldingly
arranging one of the two opposite edges on which the gauze is stretched, so that on
the movement of the sieve that edge can move somewhat to and fro in a given line of
direction, whereby the tension of the gauze is caused to fluctuate and choking or
clogging is prevented.
The arrangement which forms the object of this invention affords an effective
means for keeping the meshes open, as it is based on the fact that a straining of the
gauze not only in one line of direction but across and obliquely, is the most effective
means for keeping clear the meshes, since, whilst in the devices mentioned in the
commencement of this specification only the bending and stretching of the mesh fabric
tends to produce the springing out of the particles of flour, by a diagonal straining,
each little square of the gauze is changed into a rhombus and thus effects an infallible
expulsion of the particles of flour which have become set.
This arrangement is particularly effective for circularly oscillating sieves with a
plan sifter movement.
The arrangement may be such that a given point of the sieve oscillates as before in
one line of direction, but the adjacent part however in another direction so that
naturally wavy strains result or that one and the same point is pulled in various
directions.
Arrangements of the first kind are shown in Figures 1, 2 and 3 of the accom-
panying drawings. Small blocks a, bare glued on the under side of the gauze, which
blocks are mounted to slide on horizontally strained wires. The blocks a have
prescribed courses lying at right angles to those of the blocks b, and thereby during
the swinging movement of the sieve produce a straining of the gauze and an alteration
of the quadratic form of the meshes.
Forms of construction of the second kind are shown in Figures 4 and 5, and a
detail in Figure 6. In Figure 4, the block u glued under the gauze rests on a point c,
and is prevented from tilting over by means of a weight g. It bends or bows in all
directions on the movement of the sieve A and exerts the desired straining.
A block
Figures 5 and 6 show an intermediate arrangement between the two.
slides with its perforation above the centre of gravity on a round bar or wire. By
this means it thus describes two movements, first, a sliding one in the plane of the
paper, Figure 5, and a revolving or oscillating one on the round bar. The
mobility may be further increased by conically expanding the bore at both ends,
Figure 6.
The guiding of the blocks a and b may of course be effected in very different
ways; for instance by means of a revolving or ball joint. They may also if spherical
be mounted or simply rest on a smooth surface, (such as sheet metal) Figure 7.
If a limitation of the sieve surface is not objected to, this arrangement may also of
course be placed on the upper surface of the sieve gauze.
The arrangement is of course equally applicable for circular sieves.

page_text: If the blocks shown in Figures 3 & 5 be prolonged downwards to a sieve or
collecting floor lying beneath, they may there serve as distributing or separating
strips.
Such an arrangement is shown in Figures 8, 9 and 10. d are the fixed bars on
which the sieve gauze is fastened. a. are again the movable blocks as described in
Figure 1. It will be seen from Figure 10 that the blocks are obliquely bevelled off
underneath to one side. If the sieve be oscillated in a circular direction as is
indicated in the plan view of Figure 8, the sifting material will travel during one
half of this circular movement from one edge of the sieve and accumulate against
the other side y and slip through those openings i which lie more towards this side, in
the direction of the arrow indicated at A, Figure 8. During the other half of the
circular movement the sifting material will lie more removed from the edge or
border y, and press itself on the other hand against the edge a. It again slips
through the openings or recesses i,, but this time however in the opposite direction B,
Figure 8. As however the half limited by y of the sieve has one opening or recess
more than on the part enclosed by a, at each entire revolution more material to be
sifted slips or moves in one direction than in the other, and the whole material to be
sifted thus travels gradually over the sieve.
The same action is attained also without the small oblique bevellings off if the
blocks be so distributed as shown in Figure 11. In this case there is also on the
one half of the sieve one passage o more than on the other, and consequently it again
follows that the sifting material is displaced more freely towards the one than towards
the other side, and therefore as a whole makes a constant progressive movement.
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 1
claim is.
1. A device for keeping plan sieves clear and open, characterised by a number of
blocks or bodies attached to the sieve gauze and adapted to move in various directions
by means of a suitable method of attachment, either in such a way that adjacent bodies
move in different directions, or that the same body is capable of moving to various
sides, substantially as described.
2. A device for keeping plan sieves clear and open, in which the blocks, or bodies
of the kind described for clearing the sieve are prolonged downwards to serve as
distributing or separating strips for the sieve or collecting floor lying underneath,
substantially as described.
Dated this 25th day : 10S7
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant."