De Klaver or De Greate Klaver is a hollow post mill in Bolsward

Bolsward

Bolsward is a city in Súdwest Fryslân in the province of Friesland, the Netherlands. Bolsward is just short of a population of 10,000.- History :The town is founded on three artificial dwelling hills, of which the first was built some time before Christ....

, Friesland

Friesland

Friesland is a province in the north of the Netherlands and part of the ancient region of Frisia.Until the end of 1996, the province bore Friesland as its official name. In 1997 this Dutch name lost its official status to the Frisian Fryslân...

, Netherlands

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 which has been restored to working order. The mill is listed as a Rijksmonument

Rijksmonument

A rijksmonument is a National Heritage Site of the Netherlands, listed by the agency Rijksdienst voor het Cultureel Erfgoed acting for the Dutch Ministry of Education, Culture and Science.-History and criteria:...

, number 9860.

History

De Klaver was built in 1802. It drained an area of 249 pondemaat. Of this area, 34 pondemaat belonged to the mill owner, 50 pondemaat belonged to an orphanage and the remainder was divided amongst numerous other owners. The mill was in use until 1966. In that year a steel Archimedes screw replaced the existing one. This was driven by a tractor. Restoration took place over the winter of 1980-81. The restored mill was opened on 10 June 1981. It was sold in that year to Stichting Fryske Mole (English:Frisian Mills Society) for ƒ1.

Description

De Klave is what the Dutch describe as a "spinnekopmolen" (English: Spider mill). It is a small hollow post mill winded by a winch. The four Common sails, which have a span of 12 metre, are carried in a wooden windshaft. The windshaft also carries the brake wheel which has 33 pegs. This drives the wallower (17 pegs) at the top of the upright shaft, which passed through the main post

Trestle (mill)

The Trestle of a Post mill is the arrangement of the Main post, crosstrees and quarterbars that form the substructure of this type of windmill. It may or may not be surrounded by a roundhouse...

. At the bottom of the upright shaft, the crown wheel (32 pegs) drives the Archimedes screw via a gear wheel with 31 pegs. The Archimedes screw has an axle diameter of 275 millimetres (10¾ in) and is 910 millimetre diameter overall. It is inclined at an angle of 27½°. Each revolution of the screw lifts 152 litres (33.4 imp gal) of water.