The sun and the moon move according to plan. And the stars and the trees prostrate themselves. And the sky, He raised; and He set up the balance. So do not transgress in the balance. But maintain the weights with justice, and do not violate the balance. And the earth, he set up for the creatures. In it are fruits, and palms in clusters. And grains in the blades, and fragrant plants. So which of your Lord's marvels will you deny? - Quran, 55. The Compassionate (ar-Rahman) (5-13)
The water wheel turns very slowly. This is why it is coupled to a series of gears. These gears of different sizes will gradually increase the rotation speed in relation to the bucket wheel and transmit the motor torque to the millstones.
Before the industrial revolution, the water wheel, wheel shaft and interior gears were made of wood, with the exception of a few metal parts (such as the rynd and clutch, see below point d and e). However, gradually more and more wooden parts were replaced by metal. This was a consequence of the general use of steel and cast iron in the industry and of the new processing methods (turning, folding and rolling). In the majority of Flemish water mills, we can situate this around 1890: folded and riveted sheet iron for the water wheel, steel for the shafts and cast iron for the cog wheels.
Pit and pit wheel
The first gear is called the pit wheel. Inside the mill, at the lower floor, we find a pit, surrounded by a low protective wall.
The water wheel shaft penetrates the mill building and carries the pit wheel, with a diameter of 1.70 metres. The pit wheel and the next gear (see point b) are located beneath the level of the mill's lower floor.
The pit wheel is made of cast iron and has wooden cogs, which are inserted into the metal pit wheel. The following pictures also show the reduced space between the pit wheel and the interior wall of the pit.
The use of wood for certain gears may sound surprising, but is perfectly logical. The wooden cogs of the pit wheel are in contact with the cast iron pins of the lantern gearing, which is the next gear (see point b). This will minimise wear, as only the wooden cogs will wear out. Should they break, the miller can easily insert new cogs, without having to replace the entire transmission. Moreover, the alternation of wooden cogs and cast iron pins considerably reduces the noise of this gear couple.
The use of wooden cogs also exempts the miller from having to use extensive lubrication on these elements, which could cause problems in a dusty environment such as the interior of a mill.
The only elements that use grease to help with rotation are the shaft that supports the water wheel and the base of the vertical feed shaft inside the mill. We will look at the transition from horizontal shafts to vertical shafts in the next chapter.
The cogs are made of beech wood (Fagus sylvatica). This is one of the strongest wood types in the area, but at the same time it is flexible enough to withstand high torques. Beech wood cut from young trees hardly splinters, but can only be used inside the mill and does not withstand a humid environment.
The next chapter at a glance:
Where we look at an angle gear, used to transmit the horizontal rotary movement to a vertical shaft and accelerate the rotation speed.