THE PROPELLING MACHINERY OF THE U. S. S. LEVIATHAN. 237 



Mr. Anderson : — The primary cause of the damage to the high-pressure astern tur- 

 bines was due to frictional heat generated by distortion, causing the revolving rotors to come 

 in contact with the fixed cylinder casing barrel. 



There have been various statements maide to the effect that the damage was wilful 

 and deliberate, but after making a thorough examination of the turbines I became convinced 

 that this was not so. 



The impulse wheel is subjected to extreme temperature changes and a certain amount of 

 distortion is inevitable, especially when steam is turned on quickly and in large volumes. 

 The design, of the impulse wheel is such that, if there is any distortion, the dummy piston is 

 affected, because this piston is directly attached to the wheel disc by studs, and even a slight 

 distortion is to some extent magnified at the forward end of the dummy piston. (See Fig. 

 4, Plate 97.) In other words, distortion of the impulse wheel affected the revolving dummy 

 piston, which caused this to come in contact with the dummy cylinder, vi^ith the result that 

 great heat was generated, finally causing fractures in the cast iron, and in turn this produced 

 damage to the wheel buckets. 



The axial clearance between the buckets of the impulse wheel and the guide buckets 

 attached to the cylinder casing appears to be somewhat on the small side, and this allowed 

 the moving and fixed buckets to come in contact. 



The cast-iron dummy cylinder broke in both port and starboard turbines, and the broken 

 pieces apparently jammed against the revolving rotor, causing much damage and creating 

 intense vibrations and generating tremendous heat. 



The damage to the blading at the exhaust end of both turbines was probably caused by 

 vibrations, set up when the broken pieces of the dummy cylinder jammed against the rotor. 



We overcame all troubles with these turbines by removing the buckets of the impulse 

 wheel and by taking out the nozzles, which allowed tlie high-pressure steam tO' immediately 

 fill up the large inlet belt — or what is the impulse wheel chamber — and this evenly heated 

 the casing. 



Dealing with the low-pressure astern turbines, it is quite probable that this damage was 

 caused by blading material being carried over into these turbines from the high pressure 

 astern. 



The German engineers fully realized that there was something seriously wrong with 

 these astern turbines, but apparently they did not know just what to do, or they may not 

 have had time to do anything whilst the ship was in port preparing for the following trip. 

 They had cut passageways through the blade rows about 16 inches wide, and it is difficult 

 to imderstand just what they expected to gain by doing this. 



Mr. Emmet : — I had been told about the channels which were cut through the blading, 

 and it seems to me this was a matter of intentional damage. 



Mr. Anderson : — I believe this was done with a view to finding out the extent of the 

 damage in the blade rows, and I cannot see what would be gained by any deliberate or in- 

 tentional damage of this nature. It would have been better practice to cut away the entire 

 end row, and after this was done the next row would be fully exposed, and if this showed 

 damage then it in turn required cutting out, and the engineers would have found good blad- 

 ing and a rotor that would turn freely after cutting away four pairs of rows. In one tur- 

 bine we did find that a chisel had been driven right in among the blade rows, and it would 



