PRINCIPLES OF NAVAL ENGINEERING 



STEAM ^ 



INLET ^J 



147,96 



Figure 12-16.— Arrangement of nozzle control valves. 



Flexible Couplings 



96.19 



Figure 12-17.— Nozzle diaphragm. 



Propulsion turbine shafts are connected to 

 the reduction gears by flexible couplings which 

 are designed to take care of very slight mis- 

 alignment between the two units. Flexible cou- 

 plings are discussed in chapter 5 of this text. 



Reduction Gears 



Reduction gears for propulsion turbine in- 

 stallations are described and illustrated in 

 chapter 5 of this text. At this point, it is im- 

 portant merely to note that turbines must operate 

 at relatively high speeds for maximum efficiency, 

 while propellers must operate at lower speeds 

 for maximum efficiency. Reduction gears are 

 used to allow both turbine and propeller to 



332 



