Coker windmill
The coker windmill ( quiver windmill , coke mill for short ; also Wippmühle , Dutch maiden , or spinning head mill for small specimens with 7-15 m impeller diameter) is an early variant of the windmill . It developed in Holland around 1410 from the post mill .
description
The fundamental innovation of the mill type “coke mill” compared to the “post mill” was the relocation of the majority of the mill mechanics and rooms in the mill plinth, which changes from the simple stand (the “bock”) of the post mill to a firmly enclosed room with wooden walls or a stone one Part of the building. This was made possible by relocating the vertical shaft to the mill axis ("house tree") by replacing the house tree - the pivot of the post mill - with a hollow oak cylinder , the quiver ( Low German and Dutch "koker"). The vertical drive shaft (vertical shaft) now ran through this. The mill housing of the former post mill - the now much smaller wooden mill case - could now be turned around the vertical shaft itself. It now only contained the primary drive parts of the windmill (vane shaft with comb wheel and vane cross attached to the outside) and the upper end of the vertical shaft with the upper bunker ( crown wheel - energy-transmitting pin wheel), which is necessary for power transmission . Furthermore, on the outside of the back wall of the mill box, the control bar (s) of the grinder mechanism was attached ("Sterz", called " Steert " in Low German ) to turn the mill box into the wind by means of a reel , above a small one, usually integrated into the cod end Ladder accessible door that allowed access for maintenance and repair purposes. The codend usually consisted of 5 beams, which led downwards and converged at the reel, attached to two crossbars attached to the cap, one straight in the middle (often also called "codend"), the others ( called swords ) V-shaped, The outer V-beams are connected to the distant transverse timber (protrudes from the middle of the box on both sides), the inner V-beams are connected to the rear transverse timber (often on the underside of the mill box). Large coke mills had a relatively spacious stone or wooden substructure in which the miller could also live. Otherwise he resided in an outbuilding. The main mechanism was housed in this now fixed substructure of the coke mill, made of wood or masonry, with a square or rarely hexagonal floor plan with a pyramidal top. In very rare cases a gallery was added, as was the case with the later gallery mills, if the substructure was too high and the impeller was dimensioned so that the blade tips could not be reached from the ground. The name Wippmühle comes from the rocking movement of the mill box during operation, the name Dutch Maiden from the "slim waist" of the mill.
Dissemination and use
Since the first coke mills were used as scoop mills, the vertical shaft drove the Archimedean screw via the lower bunker - a pin wheel like the upper bunker . In the case of grain mills, the grinding mechanism was housed, e.g. T. distributed over 2 floors. While in Germany the coke mills were mostly used very small and almost exclusively as pump mills, in North Holland and South Holland , Friesland etc. they were much more numerous, larger (impeller diameter of 25-27 m) and often more beautiful. The largest coke mill, the "Wingerdse Molen", a polder mill (ndl. "Wipwatermolen" or "wippoldermolen"; "wipmolen" (general)) from 1513 in Grafstroom northeast of Dordrecht , has an impeller diameter (also span or flight) of 28, 1 m. Today there are still about 100 mills of this type in Holland and have a high share (~ 25%) of the remaining 420 pump mills, which in turn represent the largest mill function type with 40% of all about 1100 remaining windmills . There they were also used as grain (ndl. "Wipkorenmolen"), oil , paint and saw mills , in earlier centuries for far more applications. A former Dutch coke mill from 1780 has been in Walbeck , North Rhine-Westphalia , since 1823 , and can now be admired as the only one of its type in North Rhine-Westphalia . It has an octagonal stone substructure that tapers conically above the ground floor.
In northern Germany, a few isolated instances of the formerly widespread Kokermühle, the beginning of the find 20th century for. B. in East Friesland and in the Wilstermarsch together more than 500 copies counted, such. As the scoop-Kokermühle in Ihlow- Riepe or designed as a corn mill rare gallery hollow post mill in Edewecht . There is a replica of this grain mill, while the original can be admired in the Cloppenburg open-air museum , the museum village of Cloppenburg . A reconstruction of a coke mill, which was used to transport brine to the graduation house, has been on view at the new graduation house in Bad Rothenfelde since 2007 . A spinning head mill from Fockendorf (around 1850) with sail blades (span 14.3 m, 1 shotgun) has been on display in the " Schleswig-Holstein open-air museum" Molfsee since 1966 . Spinneret windmills were by no means used exclusively as bucket mills.
In the Dutch provinces of North Holland , South Holland and Friesland you can occasionally find a miniature version of the coker windmill (sometimes also miniature Dutch mill), which is more reminiscent of a model than a "real" mill. Their size varies between approx. 2.5 m and approx. 4 m in height. Similar to the flutter mills , they are used exclusively for drainage and have all the components of a large polder mill in reduced form. Instead of the usual crowing equipment, they are characterized by a large, wooden wind vane that protrudes from the rear of the mill and turns it into the wind. They are called Weidenmühlchen (ndl. Weidemolentje , aanbrengertje , veld- / poldermolentje ( Feld- / Poldermolentje ), poldermolentje ).
In France there is a variant of the Dutch or German coker windmill, the cellar mill ( moulin cavier ). It is basically a cellar coker mill. The substructure is conical masonry, mostly on a vaulted embankment, with another cellar room with external access under the masonry. The mill box (le cabinet de bois , la hucherolle ) corresponds to the German and Dutch mills. The vertical shaft ( gros “fer” arbre ) is made of iron or steel, not wood; the type of mill has been known mainly in the Plaine vendéenne and Anjou since the 15th century . Their use is mostly as a grinder (grain, oil etc.).
The disadvantage of this type of mill was, on the one hand, that the remaining mill case always had to be turned as a whole, but above all that it was only accessible from the outside via a ladder. So, also in Holland, from the 13th and 14th century built tower windmill with a rigid cap and the coker windmill, the "cap windmill" developed at the end of the 16th century , also called " Dutch mill" after its country of origin (as a gallery, mountain , Erdholländer) called.