Windmill The Hercules

Windmotor de Hercules, with its size and shape, is a striking appearance in the open landscape of the Kalverpolder in Zaandam. The wind motor, placed in 1922, is an American invention and a national monument.

The wind motor, about 16 meters high, was manufactured by the Vereinigte Windturbinenwerke AG in Dresden and delivered in 1922 through the Dutch importer R.S. Stokvis en Zonen in Rotterdam. This manufacturer marketed windmills under the name Herkules Metallicus. The mill is situated on the eastern Ringdijk of the Kalverpolder. This type of mill is also known as a rudder engine because of the shape of the wind wheel. The windmill consists of an auger bowl and auger with a steel structure above it carrying the motor body and wind wheel. The wind wheel (diameter about 11 m) has 30 blades and a tail consisting of a wide main vane and a side vane. The tower stands in an engine house with a platform above it. This house was installed during renovation in the 1990s and replaced the one demolished in 1986 due to danger of collapse.

The windmill is unmanned. The two wind vanes allow the mill to turn itself to the wind. When wind speeds are too high, the wind wheel is automatically turned out of the wind again. In addition, there were other advantages over the traditional windmill, the mill was already turning at low wind speeds, required less maintenance and the risk of fire was much lower.

American invention

The wind motor was developed in America and was used for irrigation purposes. Such mills were a great success and also entered the market in Europe. In the Netherlands, this type of mill was mainly used in the smaller Frisian and North Holland polders.

Wind motor De Hercules regulates the water level in the Kalverpolder. The excess water is discharged (head of 0.70m) into the ring canal of the Wijde Wormer. The Kalverpolder has an area of 170 ha and consists largely of peat meadows. The polder has been drained by watermill Het Pinksternakel since 1636. This stood along the Zaan, was replaced in 1922 by the Hercules and finally demolished in 1925.

Saved from demolition

In 1992, the Water Board De Waterlanden - successor to the Kalverpolder, which was dissolved as an independent water board in 1981 - decided to replace the Hercules with an electric pumping station. This was completed in 1993.

Fortunately, in 1992 the water board and the Society for the Preservation of Monuments of Business and Technology Zaanstreek (M.B.T.Z.) created the committee Restoring Roosmolen de Hercules. The mill was on the provincial monument list. Through various donations and funds, De Hercules could be renovated in 1995-1996. This was carried out by Machinefabriek P.M. Duyvis in Koog aan de Zaan. The house around the steel structure was done by students of Zaan schools as a learning project.

The windmill really played a role in water control until 2005. Then the electric auxiliary pumping station next to the mill took over completely and has been the main pumping station ever since. During the high water level in the Kalverpolder in early 2021, the electric pumping station was assisted by Windmotor De Hercules.

Additional

• On the other side of the polder is the Zaanse Schans.
• Movie of rotating Wind Motor

Conservation of the mill is made possible in part by the National Cultural Heritage Agency and the province of North Holland.