IMPROVEMENTS IN APPARATUS FOR GRINDING GraiN
Year: 1872

page_text: LETTERS PATENT to William Cullen, of Belfast, in the County of
Antrim, Ireland, Millwright and Engineer, for the Invention of
"IMPROVEMENTS IN APPARATUS FOR GRINDING GraiN."
Sealed the 17th September 1872, and dated the 11th April 1872.
PROVISIONAL SPECIFICATION left by the said William Cullen at the
Office of the Commissioners of Patents, with his Petition, on the
11th April 1872.
I, WILLIAM CULLEN, of Belfast, in the County of Antrim, Ireland,
Millwright and Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN APPARATUS FOR GRINDING GRAIN," to be as
follows, that is to say :—
This Invention relates to improvements designed to obtain a better
quality and greater yield of flour than heretofore in grinding wheat
or other grain; and it consists principally in causing the contiguous
grinding surfaces of the millstones employed to rotate in opposite
directions.

page_text: In the common existing arrangement with a pair of millstones placed
horizontally only one of the stones rotates, the other being fixed, and
only part of the grain is properly ground by the running stone, the
remainder of the grain being crushed or bruised against the fixed stone
and its outward progress retarded, so that considerable heating is caused,
power wasted, and the strength, color, and value of the flour impaired.
With the stones rotating in opposite directions, however, the grain in
passing from the eye to the circumference encounters a rapid and con-
tinuous cutting action from both stones without stoppage of its outward
motion, which with a diminished power insures a whiter and stronger
flour regularly and coolly ground and ready for the dressing machine.
There being less retardation, and consequently diminished friction, in
reducing the grain to flour, it follows that a larger quantity will be
ground by a pair of stones in a given time. The faces of the oppositely
rotating stones may be dressed in the ordinary way, and the stones may
be placed horizontally or vertically. Three stones may be combined
and placed either horizontally or vertically, the middle one being driven
in one direction and the two outer ones in the opposite direction. It
is preferred to have the opposite rotatory velocities equal, but this is not
essential. The stones may be driven by means of toothed gearing or by
means of belts.
In a convenient modification of the improved apparatus a pair of
stones are placed horizontally, and the lower one is fixed on a vertical
shaft extending downwards, and which is made tubular for the passage
up through it of a shaft for driving the upper stone. Reversed bevil
pinions are fixed on the two shafts so as to gear with the top and bottom
respectively of a bevil wheel on a horizontal shaft.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Cullen in the Great Seal Patent Office on
the 10th October 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
CULLEN, of Belfast, in the County of Antrim, Ireland, Millwright and
Engineer, send greeting.
3
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eleventh day of April, in the year of 3

page_text: our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said William Cullen, Her special licence that I,
the said William Cullen, my executors, administrators, and assigns, or
6 such others as I, the said William Cullen, my executors, administrators,
and 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 vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands, and
) Isle of Man, an Invention for “IMPROVEMENTS IN APPARATUS FOR GRINDING
GRAIN," upon the condition (amongst others) that I, the said William
Cullen, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what
5 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 William Cullen, do hereby declare
the nature of my said Invention, and in what manner the same is to
O be performed, to be particularly described and ascertained in and by the
following statement in writing, reference being had to the accompanying
Drawings, that is to say :—
My said Invention relates to improvements designed to obtain a
better quality and greater yield of flour than heretofore in grinding
5 wheat or other grain; and it consists principally in causing the con-
tiguous grinding surfaces of the millstones employed to rotate in
opposite directions in an improved manner, and with the aid of improved
arrangements and appliances.
In the common existing arrangement with a pair of millstones placed
> horizontally only one of the stones rotates, the other being fixed, and
only part of the grain is properly ground by the running stone, the
remainder of the grain being crushed or bruised against the fixed stone
and its outward progress retarded, so that considerable heating is caused,
power wasted, and the strength, color, and value of the flour impaired.
5 With the stones rotating in opposite directions, however, the grain in
passing from the eye to the circumference encounters a rapid and
continuous cutting action from both stones without stoppage of its
outward motion, which with a diminished power insures a whiter and

page_text: stronger flour regularly and coolly ground and ready for the dressing
machine. There being less retardation, and consequently diminished
friction in reducing the grain to flour it follows that a larger quantity
will be ground by a pair of stones in a given time.
The driving of the millstones in opposite directions introduces new |
conditions and difficulties which have to be met and provided for in a
proper construction of the various details and accessories, without which
the advantages to be expected from the reversed rotations cannot be
realised.
Since applying for the herein-before in part recited Letters Patent
I have learned that some years ago it was proposed to drive millstones
in opposite directions, but that the plan failed in practice simply from
want of a suitable adaptation of the accessory details; I therefore make
no claim to the rotating of the stones in opposite directions excepting
when it is effected by means of appliances substantially such as I have 1
successfully applied in practice and which are herein-after described.
In my Provisional Specification, lodged with my application for the
herein-before in part recited Letters Patent, I referred to an arrangement
comprising three bevil wheels as one of those that might be used for
driving the stones; but on consideration I have come to the conclusion
that such an arrangement, or any in which the stones would be driven
from rigid toothed gearing without the intervention of at least one belt,
is objectionable on account of the risk of the two stones touching each
other and causing breakage, and I therefore discard such arrangements.
When the stones are driven by belts, one or both belts can slip and so
avoid breakage should the stones accidentally touch each other.
I will now proceed to particularly describe my said Invention, and
in order that it and the manner of performing it may be properly under-
stood, I hereunto append two Sheets of explanatory Drawings to be
herein-after referred to, and representing various modifications of my
improved apparatus. In these Drawings the same reference numerals
are used to mark the same or like parts wherever they are repeated.
Figure 1, on Sheet 1 of the Drawings, is a vertical section of a
modification of my improved apparatus, comprising a pair of millstones
1, 2, placed in the ordinary horizontal position, but arranged to be a
driven in opposite directions. Figure 2 is plan of a bed plate 3 set
upon the supporting pillars 4 and furnished with an adjustable upper
bearing for a vertical tubular shaft 5 which carries the lower stone 2.

page_text: Figure 3 is an inverted plan of a dish plate 6 which is set on a crosshead
or rhynd 7 fixed on the upper end of the tubular shaft 5, and which is
formed with a turned over lip or flange 8 to cover a raised flange or
rim 9 formed on the bed plate 3, and thereby prevent the meal from
getting under the stones. The lower stone 2 is fixed on this dish
plate, and can be accurately levelled and adjusted by means of screws
10 passing through the arms of the crosshead 7. Figure 4 is a plan
or face view of the lower stone 2, and shows the details of an upper
adjustable bearing for a central shaft 11, which passes up through
the tubular shaft 5 and carries the upper stone 1 by means of the
usual rhynd or universal joint 12, shown as inverted in Figure 7.
This central shaft 11 is supported on a footstep bearing 12, in a
transverse frame piece 18 fixed to the pillars 4, this bearing being
adjustable in the usual way by means of a lever 14 and screw 15. The
bearing for the upper end of this central shaft 11 is fitted in the eye
of the lower stone 2, and consists of a box containing three equidistant
brass bearing pieces 16, which are adjustable radially by wedges 17
acted on by screws 18. The spaces between the brass pieces 16 are
filled with fibrous material, which is saturated with oil or other lubricant,
and the whole is covered with a plate to prevent dust from getting to
the bearing surfaces. This arrangement of bearing admits of the central
shaft 11 being accurately centred with reference to the lower stone 2,
and of its running with perfect steadiness, points requiring the greater
attention when both stones revolve. The proper supporting and
steadying of the tubular shaft 5 carrying the lower stone 2 is also of
great importance, and the bearing at its upper end consists of four brass
pieces 10 held in spaces formed in the plate 3, and made adjustable
radially by wedges 20 and screws 21, whilst spaces between the brass
pieces are filled with fibrous material saturated with oil or other lubricant.
The bearing for the bottom of the tubular shaft 5 is shown enlarged
in horizontal section in Figure 5, and in vertical section in Figure 6.
A brass cylinder 22 surrounds the lower part of the tubular shaft 5,
and the bottom of the shaft rests on three flat rings 23, the top and
bottom rings being of brass and the middle one of cast iron, whilst all
three are quite loose and free to revolve. Vertical grooves are formed
down the inside of the brass cylinder 22, and radial grooves are formed
on the surfaces of the rings 28, so that the oil or lubricant has free access
to every part. With this arrangement of the footstep bearing, if any
extra friction should take place between the bottom of the tubular

page_text: shaft 5 and the ring 23 next to it, some of the rings will revolve, but
the continuous lubrication will in a few seconds cause the shaft foot
to glide over its former resistance, and again revolve on the surface of
the top ring. A stuffing box gland 24 is applied beneath the footstep
bearing of the tubular shaft 5 to prevent the oil from dripping through
and down upon the parts beneath. The details of the bearing are carried
in a box 25, which is adjustable in a transverse frame piece 26 fixed
to the pillars 4. Each of the shafts 5, 11, has on it a pair of pulleys 27,
28, one of cach pair being fast and the other loose, and the shafts may
be driven in opposite directions from a single parallel shaft by means
of a pair of belts, one of which is open and the other crossed.
There are several ways in which the driving shafting and belts may be
arranged, and a few examples are shown in Figures 8 to 12, on Sheet 1, and
Figures 13 and 14, on Sheet 2 of the Drawings. The arrangement shown
in plan in Figure 8, and in elevation in Figure 9, is suitable for a series of
pairs of stones arranged in two rows. A horizontal first motion shaft
is carried along midway between the two rows, and by bevil gearing
drives a vertical shaft between each couple of pairs of stones, the open
and crossed belts extending from such vertical shaft to the shafts of
the millstones on cach side. In Figure 10, the motion is transmitted
by belts from pulleys on a horizontal shaft, directly to the pulleys on the
shafts of the millstones, the belts being led over guide pulleys to change
their direction. In Figure 11 one millstone shaft is driven as in
Figure 10, but the other one is driven by a pair of bevil wheels, both
however from the same horizontal shaft. Figure 12 is a plan showing a
convenient way of driving by belts from two horizontal shafts geared
together by spur wheels, so as to revolve in opposite directions, the belts
being twisted, but none of them crossed. The pulleys on the horizontal
shafts are supposed to be loose on the shaft, being provided with friction
clutches for putting them into or out of gear. Figure 13, on Sheet 2,
is a plan showing how four pairs of stones may be driven by belts
from a single vertical shaft, and Figuro 14 is a sectional elevation
showing an arrangement in which the upper stones are driven by means
of shafts extending upwards from them and having their pulleys above.
The footstep bearing for cach such upper shaft is guided in the eye of
the lower stone, and is raised or lowered by means of a rod passing
down through the lower tubular shaft. The faces of the oppositely
rotating stones may be dressed in the ordinary way, and the stones may

page_text: be placed horizontally or vertically. Three stones may be combined,
the middle one being driven in one direction and the other two in the
opposite direction. I prefer to have the opposite rotatory velocities
equal, but this is not essential. When combining three stones, as
described, I prefer to place them vertically.
Figure 15. on Sheet 2 of the Drawings is a sectional elevation,
showing a pair of stones 1, 2, placed vertically on two horizontal
shafts 29, 30. The grain is fed in through one, 29, of the shafts, made
tubular for the purpose, the grain being propelled along the shaft by
a screw 31 driven at a suitable speed by means of a separate pulley 32.
Figure 16 is a longitudinal vertical section, showing the combination
of three vertical stones 33, 34, 35. The middle one 34 is fixed on a long.
horizontal shaft 36, carried in outside bearings 37, and feeding screws 38,
39, are formed or fixed on this shaft at each side of the stone 34. The
outer stones 33, 35, are fixed on tubular horizontal shafts 40, 41, carried
on the inner bearings 42, and these shafts are truly bored, and. the
screw threads 38, 39, are accurately turned on their outer edges to fit,
but turn easily inside the tubular shafts, so that these may guide and
support the central shaft 36. The inner bearings 42 are made movable
on the bed frame, and can be adjusted by screws 43, so as to set the outer
stones 33, 35, nearer to or further from the middle one 34.
Having thus particularly described my said Invention, and the manner
in which the same is to be performed, I have to state that I do not
restrict myself to the precise details herein described or delineated; but
that what I believe to be novel and original, and claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,---
1. The improved system or mode of arranging a pair of millstones
to be driven in opposite directions, substantially as herein described and
delineated.
2. The combining of three millstones in such way that the middle
one rotates in one direction and the two outer ones in the opposite,
substantially as herein described and delineated.
3. The applying of two or more loose rings (23) beneath the tubular
shaft (5) as part of its footstep bearing, substantially as herein-before
described.
4 The annlving of unner hearings having radially adinstable brass

page_text: 5. The interposing of one or two driving belts in such a way that the
oppositely rotating stones shall not be connected together through rigid
toothed gearing, substantially as herein-before described.
In witness whereof, I, the said William Cullen, have hereunto
set my hand and seal, this Eighth day of October, in the year 5
of our Lord One thousand eight hundred and seventy-two.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
WILLIAM CULLEN. (L.S.)