Model of an
Oliver Evans Automated Flour Mill.
Oliver Evans' Merchant's Mill and How it Worked by Automated in 1787.
In the introduction to the plan of his new mill, Oliver Evans reported his
automated process saved 6 to 12 men and boys labor where it can be operated
by one or two men, two to three pounds of waste per bushel, from spillage,
dust, improper grinding and bolting, etc. All parts of this model moves:
The mast of the ship, the receiving elevator, meal elevators, hopper-boy,
and the bolters.
To understand how the Mill worked, start at the first floor left of the
picture. (1) Wheat which comes overland by wagon to the mill. The wheat
is dumped in the receiving hopper on the first floor close to the miller.
(2) A ship has come alongside the mill. The wheat is picked up from the
ships hold by a marine elevator that is movable and swings from the head
out into the ship. This is not visible in this photo of the model. Also
not visible is the water wheel turning through the window. The grain from
the marine elevator comes into the mill on the right attic level. It is
poured into a small hopper. Then the grain is carried across the mill in
a conveyor on the underside of the attic floor. The spout on the other side
of the conveyor dumps the grain into the uncleaned hopper-garner where it
is mixed with the wheat from the overland wagon.
(1) A grain sack (from the overland wagon) is emptied into the receiving
hopper. From the grain sink below the receiving hopper the grain flows down
a chute to the grain elevator. The elevator is an endless strap filled with
small carved wood cups, three sided wooden cups with a leather bottom and
leather strap that holds them to the moving belt or soldered sheet tin cups
which fill themselves at the elevators boot (bottom) and empty themselves
at the head (top). The grain falls down a chute to the uncleaned hopper-garner
on the mill's second floor.
[What is not built into the model is the next step. Wheat goes directly
by a chute to the main wheat elevator.. The wheat is carried to the attic
level of the mill where it then goes by a chute into the rolling screen
(which is built like a flour sifter or bolter, but with two larger size
mesh screen that the bolter), and a cleaning fan known as a smutter. The
smutter may be connected directly to the tail end of the rolling screen,
or to the short elevator that lifts it to the top of the smutter. The grain
then go to a conveyor which pours it into a series of clean wheat bins on
the floor below. The grain is dumped in the opposite is supposed to be
fed in turn to through board under the cog wheel. Each garner holds two
thousand bushels of wheat, twelve thousand in all. As the wheat is ground
by the millstones, it falls to the meal conveyor, which takes it to the
meal elevator. This raises it to and it runs down the hopper-boy, which
spreads and cools it over an area 10 to 15 feet in diameter.]
(1-A) The grain falls down a chute from the wheat-garners over the millstones.
The wheat is ground by the millstones, then it falls down a chute to the
meal elevator. The meal elevator lifts it to the top of the floor where
it falls down a chute to a chop-bin above the second set of millstones.
The second set of millstones regrind the chop, and the falls down a chute
to the flour elevator where it is again lifted to the top of the mill. It
falls down a chute to the hopper-boy, which spreads outward turning it over
and over again, thus cooling it over an area 10 to 15 feet in diameter.
(1-B) Thirty or more barrels of flour at a time can moving through the milling
system at any one time. The cooled meal falls down a chute at the center
of the hopper-boy to the first bolter. The fine flour and middlings go into
a double of divided bins on the basement level. The tailings from the first
real go down a chute to second flour elevator where it is again lifted to
the top above a second bolter. The bolter sifts the flour once again. The
bolted second grade of flour goes to a single bin on the mills basement.
The product of the second grade goes down a chute to be re-sifted once again.
The tailings now go out a chute where the reminder is discarded outside
of the mill. From the packing-chests the flour is placed in the barrels.
The barrels goes to the weighing device, which is a large hanging beam scales.
Then the flour would be pressed into barrels so the weight of each barrel
contains would 196 pounds of flour. Each barrel is stamped (branded with
a heated branding iron) to show that it contains 196 pounds of flour when
it was produced. The barrels of flour would be then headed and rolled
to the door where it is lowered back to the ship it came from, or be returned
to the overland wagon.
Young Mill-Wright and Miller's Guide, by Oliver Evans, Chapter 10,
Article 89, Application of the Forgoing Machines in the Process of Manufacturing
Wheat into Superfine Flour, and Plate Number 8, 1795. http://www.angelfire.com/journal/pondlilymill/plate.html
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