Design Tower mill

dutch windmill de noord, schiedam

the advantage of tower mill on earlier post mill is not necessary turn whole mill ( body , buck ) machinery wind; allows more space machinery storage. however, select tower mills found around holland constructed on wooden frame rotate entire foundation of mill along cap. these towers constructed out of wood rather masonry well. movable head pivot react changing wind patterns important aspect of tower mill. ability gave advantage of larger , more stable frame deal harsh weather. also, moving cap easier moving entire structure.

in earliest tower mills cap turned wind long tail-pole stretched down ground @ of mill. later endless chain used drove cap through gearing. in 1745 english engineer, edmund lee, invented windmill fantail – little windmill mounted @ right angles sails, @ rear of mill, , turned cap automatically bring wind.

like other windmills tower mills have 4 blades. increase windmill efficiency millwrights experimented different methods:

automated patent-sails instead of cloth spread type sails didn t need sail cross stopped spread or remove cloth sails because altered surface inside mill means of controlling gear.
more 4 blades increase sail surface.

therefore, engineer john smeaton invented cast-iron lincolnshire cross make sail-crosses five, six, , 8 blades possible. cross named after lincolnshire used.

there several components tower mill in 19th century in europe in developed stage, elements such gallery not present in tower mills:

stock – arm protrudes top of windmill holding frame of sail in place, main support of sail , made of wood.
sail – turning frame catches wind, attached , held stock. traditional style found on tower mills four-sail frame, in mediterranean model there eight-sail frame. example of in st. mary s mill on isle of sicilly constructed in 1820.
windshaft – particularly important part of sail frame, windshaft cylindrical piece translates movement of sail machinery within windmill.
cap – top of tower holds sail , stock, piece able rotate on top of tower.
tower – supports cap, main structure of tower mill.
floor – base level of tower inside, grain or other products stored.
gallery – deck surrounding floor outside tower provide access around tower mill if raised, not present in tower mills. gallery allowed access sails making repairs because not reached ground in larger mills.
frame – sail design forms outline of sail, meshed wood design covered in cloth. mediterranean design different in there several sails on sail-frame , each supports draped cloth , there no wooden frame behind it.
fantail – orientation device attached cap, allowing rotate keep sails in direction of wind.
hemlath – thick wooden sailbar on side of frame keeps narrower sailbars inside sail.
sailbar – elongated piece of wood forms sail.
sail cloth – cloth attached sail collects wind energy; large sail cloth used weak winds , small sail cloth strong winds.




^ journal of franklin institute, volume 187 (1919), 177
^ miller in eighteenth century virginia (1958), 7
^ cipolla before industrial revolution: european society , economy, 1000–1700 (1994), 144
^ http://visual.merriam-webster.com/energy/wind-energy/windmill/tower-mill.php visited 23 november 2009
^ ball, natural sources of power (1908), 248