TURBINES 



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the speed governor simultaneously, but in opposite directions. 

 The auxiliary nozzle opens when the power nozzle closes and vice 

 versa, the volumetric relationship between the two being adjusta- 

 ble, according to the conditions at the plant. This, in itself, would 

 prevent any pressure rise in the pipe conduit, but would not 

 afford any economy in water consumption. In order to save 

 water, it is necessary to keep the auxiliary relief nozzle closed 

 during a partial and slow motion of the main needle and also to 

 have it close at a safe rate of speed after it has been opened. This 



FIG. 117. 10,000 Horse-power Auxiliary Relief Type Nozzle. (Built by 

 Pelton Water Wheel Company.) 



result is accomplished by a cataract cylinder or dashpot which is 

 inserted in the operating gear of the auxiliary relief needle. 



Fig. 117 illustrates a 10,000-H.P. auxiliary relief type nozzle 

 with direct-motion governor. Alongside the wooden scaffolding 

 is the governor oil-pumping system. To provide pressure oil to 

 operate the governor piston, this pumping set is operated by a 

 water wheel arranged with a control so that the wheel and pump 

 operate only when the level of oil falls below a predetermined 

 point. 



