IMPROVE- MENTS. IN DRESSING OR SIFTING FLOUR OR MEAL
Year: 1856

page_text: LETTERS PATENT to Andrew Dunlop, of Glasgow, in the County of
Lanark, North Britain, Grain Merchant, for the Invention of "IMPROVE-
MENTS. IN DRESSING OR SIFTING FLOUR OR MEAL."
Scaled the 31st March 1857, and dated the 6th October 1856.
PROVISIONAL SPECIFICATION left by the said Andrew Dunlop at the:
: Office of the Commissioners of Patents, with bis Petition, on the 6th.
October 1856.
I, ANDREW DUNLOP, of Glasgow, in the County of Lanark, North Britain,
Grain Merchant, do hereby declare the nature of my said Invention for
"IMPROVEMENTS IN DRESSING OR SIFTING FLOUR OR MEAL," to be as follows, that'
is to say:-
This Invention relates to an improved system or mode of dressing or sifting
the flour or meal of wheat or other grain, wherein the operation is effected by
alternately slackening and tightening the dressing cloth, consisting of a
suitable permeable material, such as is used in ordinary. dressing, machines.
The dressing cloth is disposed horizontally as regards its width, but with a
slight inclination longitudinally, and the meal or flour, being placed upon it at
its bigber end, is powerfully shaken by the rapid slackening and tightening.
action; the coarser particles being thrown higher than the finer particles ;
thus, in, falling, the finer particles reach the cloth first, and are rapidly sifted.

page_text: through it, whilst the portion which does not pass through the cloth gradually
finds its way to the lower end of the apparatus..
According to one modification of apparatus for carrying this system into
effect, the dressing cloth is attached at the sides to longitudinal bars, which
are stretched apart in a suitable frame by means of springs. Each bar is
connected by rods or cords crossing below the cloth to a lever on the opposite
side, and the two levers are acted upon, either directly, or through the
intervention of other levers, by cams or projections on a continuously revolving
wheel, in such a manner that at short intervals the levers draw the two bars
together, so as to slacken the dressing cloth, or cause it to bag down between
the bars, and then suddenly release the bars, so that the springs draw them
apart again and tighten the cloth. The apparatus is formed with vertical sides,
consisting of cloth or other suitable flexible material, attached to the shaking
bars at their lower edges and to a covering framework above. In attaching
the dressing cloth to the shaking bars it is necessary that this should be done
with sufficient security to resist the stretching action of the springs..
According to one plan, the dressing cloth is attached to the bars near the
edges by means of small pins fixed in the bars at about half an inch apart.
Between the bars and the dressing cloth théré is placed a strip of india-rubber
cloth through which the pins protrude, and above the dressing cloth the
vertical side cloths are also passed upon the pins, and the whole is bound
together by covering strips of wood, screwed down to the bars, and formed with
recesses to receive the points of the pins. In this way the dressing cloth is
not only held by the pins, but is also nipped between the india-rubber cloth
and the edge of the vertical side cloth, and is thus enabled to resist the
stretching action. This dressing or sifting apparatus acts very effectually
upon the flour, or meal, and the dressing cloth never gets choked up, the violent
tightening action keeping the interstices always' clear.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Andrew Dunlop, in the Great Seal Patent Office on the
6th April 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDREW'
DUNLOP, of Glasgow, in the County of Lanark, North Britain, Grain Merchant,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixth day of October, in the year of our Lord

page_text: One thousand eight hundred and fifty-six, in the twentieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Andrew Dunlop, IIer, special license that. I, the said Andrew Dunlop, my
executors, administrators, and assigns, or such others as I, the said Andrew
Dunlop, my executors, administrators, or assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise, and
yend, within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN DRESSING OB
SIFTING FLOUR OR MEAL," upon the condition (amongst others) that I, the
said Andrew, Dunlop, by an instrument in writing under my hand and
seal, should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and cause the
same to be filed in. the Great Seal Patent Office within six calendar months
next and immediately after the date of the said Letters Patent.
. NOW KNOW YE, that I, the said Andrew, Dunlop, do hereby declare the
nature of my said Invention, and in what manner the same is to be performed,
to be particularily described and ascertained in and by the following state-
ment in writing, reference being had to the accompanying Drawings, and to
the letters and figures marked thereon, that is to say:
My said Invention relates to an improved system or mode of dressing or
sifting the flour or meal of wheat, or other grain, wherein the operation is
effected by alternately slackening and tightening the dressing cloth, consisting
of a suitable permeable material, such as is used in ordinary dressing
machines. The dressing cloth is disposed horizontally as regard its width,
but with a slight inclination longitudinally, and the meal or flour, being placed
upon it at its higher end, is powerfully shaken by- the rapid slackening and
tightening action, the course particles being thrown higher than the finer
particles; thus, in falling, the finer particles reach the cloth first and are
rapidly sifted through it, whilst the portion which does not pass through the
cloth gradually finds its way to the, lower end of the apparatus.
...According to one, modification, of apparatus for carrying this system into
effect, the dressing cloth is attached at the sides to longitudinal bars, which
are stretched apart in a suitable frame by means of springs. Each bar is
connected by rods or cords crossing below the cloth to a lever on the opposite
side, and, the two levers are acted upon, either directly or through. the
intervention of other levers, by cams or projections on a continuously revolving
wheel, in such a manner that at short intervals the levers draw the two bars
together, so as to slacken the dressing cloth, or cause it to bag down between

page_text: the bars, and then suddenly release the bars, so that the springs draw them
apart again and tighten the cloth. The apparatus is formed with vertical
sides, consisting of cloth or other suitable flexible material, attached to the
shaking bars at their lower edges and to a covering framework above. In
attaching the dressing cloth to the, shaking bars it is necessary that this
should be done with sufficient security to resist the stretching action of the
springs.
According to one plan, the dressing cloth is attached to the bars near the
edges by means of small pins fixed in the bars at about half an inch apart.
Between the bars and the dressing cloth there is placed a strip of india-
rubber cloth through which the pins protrude, and above the dressing cloth
the vertical side cloths are passed upon the pins, and the whole is bound
together by covering strips of wood, screwed down to the bars, and formed with
recesses to receive the points of the pins. In this way the dressing cloth is
not only held by the pins, but is also nipped between the india-rubber cloth
and the edge of the vertical side cloth, and is thus enabled to resist the
stretching action. This dressing or sifting apparatus acts very effectually
upon the flour or meal, and the dressing cloth never gets choked up, the
violent tightening action keeping the interstices always clear.
And in order that my said Invention may be properly understood, I shall
now proceed to describe the several illustrative Figures on the explanatory
Sheet of Drawings which I have hereunto appended for the purpose of
showing certain modifications under which my improvements may be
judiciously carried into effect.
Figure 1 is a plan of one modification of a machine or apparatus for
dressing or sifting flour or other meal as arranged and constructed according
to my Invention; Figure 2 is an end elevation, corresponding to Figure 1, the
interior of the apparatus being shown in section; Figure 3 is a side elevation
of the actuating wheel, shown separately; Figure 4 is a front end view of a
sifting and dressing machine, in which the flour or meal is separated from the
bran first, and the flour or meal divided into portions of different degrees of
fineness; Figure 5 is a longitudinal elevation of the machine, with a portion
of the casing at the side removed in order to show the internal arrangement;
Figure 6 is a sectional elevation of the back of the machine, or end opposite
to that shown in Figure 4.
The essential feature of the arrangement shown in Figures 1 and 2 consists
of a dressing cloth secured to parallel side bars, to which a rapid vibratory
action is imparted by means of springs and levers. The rectangular wooden
framing A encloses the space in which the sifting or dressing apparatus is

page_text: fitted. The dressing cloth B is firmly secured in its longitudinal direction to
'the vibrating side bars C, from which the vertical cloths D are carried up to
the upper part of the machine, so as to inclose the space into which the
unsifted flour or meal is fed. The chamber or space below the dressing
cloth B is also enclosed by cloths E, which are fastened to the vibrating
bars C. The dressing cloth B is stretched between the bars C, and is fitted
in the machine at an angle, so that the undressed flour or meal which is fed in
at the upper end of the cloth gradually descends the incline, the coarse
particles and bran passing off at the lower end. To enable the dressing
cloth B to withstand the jerking action of the vibrating bars C, particular
attention must be paid to the manner of securing it to the bars. The arrange.
ment which I prefer is as follows:-In each vibrating bar C are fixed a number
of metal pins, by preference of brass; these pins project above the surface of
the bars, and should be placed at about half an inch apart; their position is
indicated in the Drawing by a dotted line F, at the upper edge of the dressing
cloth B, Figure 1. Strips of india-rubber cloth or other suitable material
are pressed over the points of the metal pins till these strips are close to the
bar C, and the pins project through the cloth; the longitudinal edges of the
dressing cloth B are then pressed over the points of the pins till the dressing
cloth is close to the india-rubber cloth, and above the dressing cloth the lower
edge of each of the vertical side cloths D is pressed over the points of the pins
till they project through it; finally, the whole is firinly secured together by
strips or battens of wood G, which are fastened by screws to the bars C. In
the under side of the battens G a groove or series of holes are made to allow
for the projecting ends of the pins, and admit of the battens being screwed
down closely to the bars C. If wire cloth be chosen as the dressing cloth
the metal pins and strips of india-rubber can be dispensed with, and the
edges of the wire dressing cloth should be made to extend so far through
between the strips or battens G and the bars C as to be turned up and be
attached by means of small tacks to the outermost edges of the battens G.
The dressing cloth B is stretched or distended in a transverse direction
by means of springs secured to the framing of the machine. The springs H
are bolted to the exterior of the sides of the framing A, and are
curved outward, as shown in Figure 1, and through a hole made in the
outer end of each a link rod I is passed. Each of the link rods I is made
with an eye at its inner end, which is passed on to a hook J, screwed to the
bar C, and the outer end passes through a bracket K bolted to the framing A.
A screw thread is cut on each of the link rods I, and to them are fitted the

page_text: nuts L, by which the pressure of the spring may be adjusted, the-screwing
inwards of these' nuts obviously tending to increase the outward pressure of
the springs H, and the consequent tension on the dressing cloth B: The
mechanical arrangement by means of which the side bars Care brought
nearer to each other is fitted at one end of the machine, and is shown in tlie
Drawing on the left-hand side of Figure 1; and also in the end elevation;
Figure 2. The shaft M is driven-by'a band passing 'round the pulley. N fast
to the shaft M; which is also fitted with a loose pulley O, to throw the'machino
out of action. The shaft M gives motion to a wheel P, which is keyed thereto;
and this wheel is shown separately' in Figure 3; it consists of fours or other
number of arms springing from a central boss, and on the side which is
uppermost of each of these arms when passing between the levers Ra
wedge-shaped piece of metal or wood Q is secured by means of bolts or screws!
On each side of the wheel P is a lever R; which turns on a pin or bolt
projecting from the inner side of the transverse stay of tlie framing A. The
upper and inner ends of the levers R rest against the arms of the wheel P
and their lower ends are connected to the rods S, each of which is fast to a
lever T fitted beneath the sides of the framing A. The fulcrum of each
lever T is a bolt U, which passes through the side pieces of the framing, and
the inner end of each is connected to the side bars C by a link V, or other
suitable attachment. The undressed flour or meal is fed into the machine
through the hopper W, bat is prevented from falling directly on to the dressing
cloth below; and is scattered by means of the disc 'X, which is fitted beneath
the mouth of the hopper. This disc is carried by a framing Y, attached to the
side bars at the upper part of the framing. The ropes Z, which are fastened to
the upper side bars a and to the eyes in the vibrating bars C, serve to support
the latter. The side cloths D, and the cloth forming the top of the sifting
chamber, are attached to the upper side bars a, so as to completely enclose it,
and thereby prevent any waste of the flour. The action of the mechanism
for shaking the dressing cloth is as follows:-When the wheel P is caused
to rotate in the direction indicated by the arrow in Figure 1. the wedge
pieces Q pass successively between the levers R, causing each of them to turn
upon its' fulcrum, and force the outer ends of the levers T outwards: By this
action the levers T force the side bars C nearer to each other, and overcome
the outward pressure of the springs H, which slackens the dressing cloth,
causing it to drop in the centre. The instant, however, that one of the
wedges Qlias passed between the levers R the springs H tighten the dressing
cloth, and thus, by the action of the wheel P, and the levers R.and T, and the

page_text: reaction of the springs H, a rapid slackening and tightening action is exerted
on the dressing cloth. The effect of this compound motion is ito: cause the.
unsifted flour to be thrown up from tlie surface of the.dressing cloth; the:finer
particles of the flour reach the cloth first (being thrown to a less height) and
pass through the interstices of the cloth to the chamber beneath; which is
enclosed in a manner similar to that of the sifting chamber, the bran, and
particles of flour or meal which are too coarse to pass: through: the dressing.
cloth are carried. into a suitable receptacle at the lower end of the dressing
cloth.
The second modification of my improvements in dressing or sifting flour.or
meal is shown in Figures 4, 5, and 6 onmy: Sheet of Drawings. In the
apparatus or machine shown under this modification, the, bran is separated
from the flour or meal first, and the remainder ist divided into portions of
varying degrees of fineness, and differing tin their commercial value. In this
machine there are a series of dressing::cloths arranged one above the other in
what may be called storeys or flats, and differing in the fineness of the intera
stices or meshes through which the flour passes. The sides of the wooden
framework A of the machine are fitted with a series of flap-doors:B, corre
sponding to the number of divisions into which the machine is divided by the
dressing cloths CBy means of these: doors access.may be had to the interior
of either of the compartments of the machine. when required. The dressing
clothis are fastened to the vibrating bars Daby means of pins and battens; or
otherwise; as herein-before described in reference to Figures and 2: The
dressing cloths C, and their side bars D; are arranged in a slanting or angular
position, as shown in the longitudinal elevation;:: Figure: 5; and they are:sup=
ported by pendant brackets E, fast on the rods F.. At the front: part of the
machine the ends of the rods Fare carried in the framing and project through
it, and to the end of each is attached a lever G, which is connected byaa
link II to an arm I fast on the sliding bar or rod J; which slides in the
brackets K: On the lower part of the sliding bar J. are two rollers. L, and a
vertical reciprocatory motion-is given to the bar J. by means of a heart-shaped
cam M, which rotates between these rollers, and alternately raises and
depresses the sliding bar. The bar J at the part between the rollers L. is
enlarged laterally; and a slot is made therein to admit of the end of asshort
horizontal shaft N passing through it, and which is carried by a bearing at the
back of the sliding bar J, and in front of a bearing depending from: the
projecting framework O of the machine.. The shaft: N. has keyed upon it
the heart-shaped cam M, the driving band pulley P, and bevil pinion Q, which
latter is in gear with a cog wheel R on the shaft S, and gives motion by means

page_text: of a band to the pulley T. The spindle of the pulley T passes through from
side to side of the machine, and carries upon it a pair of band pulleys U, and
at the opposite end of the machine is a corresponding pair of pulleys, over
which is passed a pair of bands V, to which are attached the scrapers W.
The unsifted flour or meal and the different qualities thereof are prevented
from mixing with each other by means of the cloths X, or other impervious
and flexible material; which are fastened to the sides of the machine, and pass
over tlie rods F, the lower edges being secured to the vibrating bars D.
At the back or lower end of the machine the ends of the cloths X are
formed into a sort of pocket, which deliver the bran and all but the finest
quality of flour into shoots or spouts appropriated to each quality. This part
of the machine is enclosed by a door, by means of which access is readily had
to the ends of the compartments and to the shoots when necessary. The
flour or meal is fed into the upper.compartment of the machine by a hopper
or other suitable arrangement, and when the shaft N is put in motion by the
driving pulley P it causes the heart or cam M to rotate, by which means the
sliding bar J is lifted and depressed. This action of the bar J turns the
rods F partially round, causing the bars D to oscillate, and thus imparts an
alternate stretching and slackening action to the dressing cloths C. The
vibratory action imparted to the dressing cloths causes the flour or meal to
pass successively through the cloths of the different compartments, the finest
particles only reaching the lowest compartment. The dressing cloth of the
upper compartment is sufficiently coarse to allow all the particles of flour to
pass through, whilst it retains the bran only, which is, carried onward to the
lower end of the compartment, and passes through an aperture Y in the end
of the inachine, and out.by the shoot or passage Z. The dressing cloth of the
second compartment is of such a degree of fineness that it retains only the
coarsest quality of flour, or meal, technically known as "thirds," which is kept
separate and passes away by the shoot or passage a. The third compartment
separates the quality of flour known as "parings," and this product passes off
by the shoot or passage b. The lowest dressing cloth separates the quality of
flour known in the trade as "sharps," which is kept apart from the others by
the shoots c, c; finally, the "superfine, or extra," falls into the chamber d and
is scraped up to one end of the machine by the blades W of the rotatory
scraper, whence it falls through the spout or shoot e.
In my Drawing, Figure 5, the egress spout or shoot e is shown at the
upper or highest end of the dressing machine; in some cases; however, it is
preferred to have, tlis at the lower end; and in this, modification the band V
of the scraper W must, be male to travel in an opposite direction in order

page_text: to carry the flour towards the lower end of the machine, as indicated by the
dotted line f.
:
By means of these modifications of my improvements, which I have herein-
before described, flour or meal is sifted or dressed very rapidly, and so
effectually as to secure more certainly than can be done by machines of less
effective action that none of the finer qualities shall be allowed to pass
amongst the coarse ones, and thus a large produce of the finer qualities is given.
The machines made according to my improvements also occupy less space
and require less dressing cloth than those called "French," and make the fine
flour purer than the common wire-cloth cylindrical machines, in which a dark
dust is scrubbed by the internal revolving brushes off the bran and other
coarse parts into the fine flour. Another very important quality which
machines made according to my improvements possess is, that although the
flour or meal to be dressed by them be taken quite warm from the stones they
will cool it thoroughly.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I may observe, in conclusion, that I do not confine or restrict
myself to the precise details or arrangements which I have had occasion to
describe or refer to, as many variations may be made therefrom without
deviating from the principles or main features of my Invention; but what
I consider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent, is,-
First, the general arrangement and construction of the machinery or appa-
ratus for dressing or sifting flour or meal, by means of which this operation is
performed in a more effective and economical manner than hitherto, as herein-
before described.
Second, the system or mode of dressing or sifting flour or meal by means of
permeable fabrics which are alternately tightened and slackened, for the
purposes herein-before described.
Third, the system or mode of attaching the dressing cloths of machines for
dressing or sifting flour or meal to the side bars, whereby the cloth is enabled
to withstand the jerking action imparted to it, as herein-before described.
Fourth, the system or mode of giving a vibratory motion to the dressing
cloth of dressing or sifting machines by means of the machanical arrangements
herein-before described, and shown in my Drawing, Figures 1, 2, and 3..
Fifth, the general arrangement and construction of dressing or sifting
machines in which the flour is separated from the bran first and divided into
portions of different degrees of fineness, as herein-before described.
}
L

page_text: Sixth, the system or mode of giving a vibratory action to a series of
dressing cloths by means of the mechanical arrangements herein-before
described; and shown in Figures 4, 5, and 6 of my; Drawing.
In' witness whereof, I, the said Andrew Dunlop, have hereunto set my
hand and seal, this Third day of April;, One thousand eight hundred
and fifty-seven.
ANDREW DUNLOP. (L.s.)