STEAM TURBINES 227 



Slugs of Water. If the boiler supplying steam to a recipro- 

 cating engine primes badly, a slug of water may be carried 

 over into the cylinder, resulting in a cracked piston or cylinder, 

 a buckled piston rod or connecting-rod, or a wrecked frame. 

 In case a steam turbine is used, however, the danger is greatly 

 lessened. In turbines in which the blades are not supported 

 at their outer ends, the \vater may cause stripping of the blades; 

 but this is not very likely, as the blades at the high-pressure 

 end of the turbine are short. A rush of water from the boiler 

 has been known to bring a turbine almost to a stop without 

 damaging the blades. 



Vibration. On account of the high speeds attained in tur- 

 bine practice, the rotors are balanced accurately, so as to reduce 

 vibration. But in spite of this careful balancing, vibration 

 may manifest itself during ordinary running. It may be caused 

 in any one of several ways, but the fundamental cause is lack 

 of balance. If the rotor is warmed up too rapidly, the shaft 

 or the wheels may be warped by unequal expansion, producing 

 an unbalanced effect. The stripping of a blade or two will 

 affect the balance of the wheel and tend to produce vibration. 

 Even water carried into the turbine with the steam will bring 

 about an unbalanced condition and will lead to vibration. 

 When vibration is observed, it is well to reduce the speed a 

 little, and to note whether this causes the vibration to cease. 

 If it does, but comes back again as soon as the speed is increased, 

 the source of the trouble should at once be determined. 



OPERATION OF TURBINES 



Inspection. If the steam turbine is a new one, or if it has 

 been standing idle for a long period, it should not be started 

 until it, together with its auxiliary apparatus, has been thor- 

 oughly inspected. The bearings should be properly adjusted 

 and free from dirt, and the entire lubricating system should 

 be clean and filled with clean oil. The steam pipe from the 

 boilers should be blown through, so as to clear it of any foreign 

 matter that could be carried into the turbine by the steam. 

 The governor mechanism should be examined, to see that it 



