PELTON WHEEL 439 



ART. 125. THE PELTON WHEEL. 



The Pelton wheel (Fig. 194 l } is the only form of water-wheel which is 

 adopted for use with high heads, and where a limited supply of water 

 under such a head is available it often forms the most suitable type of 

 prime mover. In such a case the turbine proper, with the exception of 

 the Girard type (Art. 129), is unsuitable, as will be seen later (Art. 128), 

 while where the supply water is charged with sand or similar matter in 

 suspension, as is not unusual, the Pelton wheel, on account of the 

 simplicity of its construction and of the ease with which its buckets can 

 be renewed, has manifest advantages over the Girard turbine. The 



FIG. 194. Pelton Wheel. 



pressure water is supplied through a pipe line terminating in one or 

 more nozzles which play on to a series of buckets fixed around the 

 periphery of the wheel. 



The latter is a development of the old hurdy-gurdy of the Pacific Slope. 

 This consisted of a wheel having a rim to which a series of flat plates 

 were fixed radially, the jets from one or more nozzles impinging freely 

 on these and causing rotation. Under these conditions, the theoretical 

 efficiency cannot exceed 50 per cent. (p. 378), while in practice loss by 

 splashing, friction, etc., reduces this to about 30 per cent. 



1 By courtesy of Messrs. Gilbert, Gilkes & Co., Ltd., Kendnl. 



