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Wind Power. 



[feb , 1 910. 



have a very deteriorating effect not only upon the gearing, 

 but upon the whole structure generally. 



The gearing of the machine varies in the different types, 

 the most important distinction being that in most pumping 

 mills it is arranged so that the crank is at the wheel-head, 

 and the centre shaft running down the tower assumes the 

 function of a long pump-rod having an up and down move- 

 ment. In power mills, on the other hand, the movement of 

 the centre shaft (Fig. I., CS) is rotatory, driving a foot-gear 

 (Fig. II.) which, in its turn, engages a horizontal driving 

 shaft (Fig. II., HS), thus transferring the power into 

 a neighbouring building. Power mills, unlike pumping 

 mills, can be used for both purposes, and a special 

 pump gear for this purpose (Fig. III.) can be affixed at the 

 base of the tower. In some of the older machines the line 

 shaft was made much heavier than was necessary. Under 

 any circumstances the friction on the foot-gear is great, but 

 this has been much reduced not only by lightening the shaft, 

 but by providing a ball bearing at the base of the shaft. 

 Improving the gearing in this, and similar ways, increases 

 the efficiency of the machine. Owing to the great exposure 

 to which windmills are subjected, all external iron work 

 should be galvanised, and all bearings lubricated at least 

 once a week. The life of the machine is thereby greatly 

 lengthened. 



Towers. — The tower (Fig. IV.) which supports the 

 machinery is a very important factor influencing the efficiency 

 of the machine. The older types of towers, like the present 

 home-made ones, were constructed of wood, but modern 

 towers are built of riveted steel girders braced both hori- 

 zontally and diagonally. Three-post towers are generally 

 used for pumping mills, and four-post for power mills. The 

 tower must always be high enough to expose the wheel freely 

 to the wind, a general rule being that the base of the wheel 

 should be elevated 15 ft. above any obstruction within 600 ft. 

 of the windmill. Most steel towers are made in 10 ft. sections. 

 The foundation of the tower should consist of four blocks of 

 concrete with an anchor-post embedded in each. 



Management.- — The management of the modern windmill 

 is comparatively simple, but it demands on the part of the 



