Rodet

A mill with rodet or mill with pirouette is a type of Water mill with vertical Axe.

Its name comes from the rodet or pirouette , unit made up of the horizontal Roue hydraulic, the Arbre and the revolving Meule (higher grinding stone).

Description

The mill with rodet is composed, according to the terminology of use in the Midi:

of a granouillé (frog), which is the hollow stone in which the axis of the mill rests.
of a gulho (switches), metal part fixed at the bottom of the axis out of wooden and which rests in frog.
of a aouré (tree) in Wood.
of a coupo (spoon) which is the wheel intended to receive the jet of Eau which arrives of the right-sided by the canélou (gun), which can be closed by the paro (valve).

The lower half of the mechanism is " humide".

History

The horizontal wheels exist since strong a long time and probably preceded the vertical wheels. One finds some a little everywhere: in France (South-eastern, Corsica, Finistere) in Central Europe, Asia. In the Finistere, some were used until 1985.

In its Hydraulic architecture , Bélidor (1697-1761) of described three kinds:

the first is the " rodet" or " rodet volant" presented above. This name comes from South-east; in Finistere, one names it " pirouette".
the second comprises a tank which obliges water to turn with the wheel. It is the Moulin of bazacle represented in the Encyclopédie of Diderot and D' Alembert.
the third comprises also a tank, but the wheel is Tronconique.

Technique

The mill with horizontal wheel is relatively easy and economic to build.

Indeed, it also does not comprise any Engrenage nor Bevel gearbox, since the horizontal wheel chock is placed directly on the Axe of the Meule, horizontal, and the number of revolutions of the wheel is sufficient for the grinding stone, without there needing multiplication.

But, for the pirouette, one needs good a Chute, about four meters, so that water acquires a sufficient speed. And the hydraulic Rendement of this wheel is weak, approximately 25% like that of the Roue in lower part. Also one generally finds the pirouettes on small brooks whose low flow could not make profitable more important installations. When the Débit is really weak (in particular with the low water level), one creates a pond of reserve to store water and the mill functions intermittently.

With such a mill, to grind 100 kg of grain, under a fall of four meters, one needs 600 cubic meters of water. Also the Meunier S tested various models of Palette S to improve the output and invented the Cuiller. But this spoon does not give better results that the pallet quite tilted punt, which is much easier to build. When, about 1825, the engineer Burdin was interested in this wheel, he invented the first Turbine. The impulse turbine of Pelton (1825-1908) functions according to the same principle that the pirouette, but its output is of 80%.

See too

External bonds

mill with rodet
Image
standard of mills
glossary, via the term of the mills
Association of Historical research on the mills