492 



HYDRAULICS AND ITS APPLICATIONS 



diameter, and regulation is performed by an annular bronze ring operated 

 by an oil pressure relay governor (see Art. 139), and arranged so as to 

 close by its own weight. 



Power is transmitted through a tubular steel shaft 38 inches in diameter, 

 the weight of this shaft, which is 120 feet long and weighs 71 tons, being 



i 2 3 4 5 



10 



15 



ZOFeet 



Scale of" Lengths. 



FIG. 234B. Sectional Elevation of Double Francis Turbine for 10,250 H.P. Canadian 



Niagara Power Co. 



balanced by the upward pressure on the balance piston P, which is 4' 5" 

 diameter. The under side of this piston is exposed to the full supply 

 head by means of a pipe not shown in the sketch, and any leakage past 

 the piston escapes directly into the tail-race. Any unbalanced end thrust 

 on the shaft is taken up by means of a thrust bearing on the top deck. 

 The draught tube is forked to keep the tail-race free, and is arranged so 

 as to give 22 feet of suction head. 



