How a windmill works

Mécanisme d’entraînement des meules = Millstone driving mechanism

 Rouet = brake wheel / Alluchons = teeth / Arbre tournant = wind shaft / Tourte, / Fuseau / Lanterne = wallower / Gros fer = drive shaft / Meules = millstones

The wind speed must be between 40 and 60 km/h in order for the sails to turn. When this is the case, the sails turn the wind shaft, which in turn drives the brake wheel. The brake wheel’s 40 teeth then engage the wallower, which drives the rotating grindstone.

At each quarter-turn, the drive shaft shakes the hopper assembly, causing the grain to fall at a regular rate into a hole in the centre of the millstone. The grain is then carried under the grindstone and crushed. A brush which forms a part of the grindstone pushes the powder towards an opening and into a chute. Here, the powder is collected, and either carried away in sacks for sieving, or directly thinned into flour in a sieve.

Millrind

Spindle

Oeillard = eye / Meule tournante = runner stone / Anille = millrind / Meule dormante = bed stone / Bague = mace / Boitard = bearing box / Petit fer = spindle / Crapaudine = grating

 Cross-section of millstones, millrind and spindle

The spindle serves to lift the runner stone by means of the millrind, allowing the runner stone to make its turns and adjusting the distance between the runner and bed stones.