426 



HYDKAULICS AND ITS APPLICATIONS 



type of motor. In general, apart from mechanical friction, water-wheels 

 suffer chiefly from the causes outlined in sections (a), (b), and (d) ; tur- 

 bines from those in sections (a), (c), and (d) ; while losses due to shock 

 and eddy production, (a) and (b), are all-important in piston engines. 

 These types of prime mover will now be considered somewhat in detail. 



ART. 120. THE OVERSHOT WATER-WHEEL (Fio. 185). 

 In this type of wheel water is supplied near the highest point of the 





FIG. 185. Overshot Water-Wheel. 



circumference to a series of buckets formed by vanes connected at each 

 end to circular shrouds, the bottoms of the buckets being formed by the 

 inner circumference of the wheel. For convenience of construction the 

 vanes are often made of wood and in two parts, the inner part being radial 

 and the outer inclined to this at an angle depending on the speed of the 

 wheel and the velocity of the supply stream. 



