THE PROPEUJNG MACHINERY OF THE U. S. S. LEVIATHAN. 229 



dummy cylinder and the brass fin strips had fused in lumps on to the surface of 

 the piston. 



(d) The four last rows of the rotor blades and three rows of top and bottom 

 casings, together with the blading cut out in the pocket, all required renewal. 



The following repairs were made: — 



A new cast-iron dummy cylinder was fitted. This was made in six pieces, three 

 for the lower half and three for the upper. 



Attempts were made to chip, file and grind the dummy piston of the rotor, but 

 this was not satisfactory, and eventually this was machined and new dummy fin 

 strips fitted. To machine the dummy piston, the rotor was lowered into place and 

 connected up with the turning gear, a cut was taken across the surface and the 

 grooves for the fin strip were turned out. 



All the damaged blading at the exhaust end of rotor and casing was renewed, 

 the total number of new blades being approximately 6,500. 



After careful consideration it was deemed advisable not to refit the impulse 

 wheel buckets, inasmuch as the indications tended to show that the blading troubles 

 were caused by distortion of the impulse wheel under steaming conditions. There- 

 fore the three rows of buckets in the rotor wheel were removed, together with the 

 two segments of casing guide vanes, as well as the nozzles in the cast-steel chambers. 



This turbine was opened up early in June and closed up on October 11, 19 17. 



Low-Pressure Astern {Port Outboard). — When this turbine was opened up, 

 the following blading repairs were found necessary : — 



Rotor. — (a) The first four rows and part of the fifth row at the steam inlet 

 end were damaged. 



(&) First row of second expansion stage. 



(c) The last two rows at the exhaust end, together with a pocket 15 inches 

 wide cut through nine rows of blades. 



Lozver half ca.nng. — The first four rows of the steam inlet end and the first 

 row of second expansion all badly damaged. 



Top casing. — The first four rows at the steam inlet end, the first row at the 

 second expansion, and part of the last two rows at the exhaust end were damaged. 

 In addition to this, a pocket 15 inches wide was cut through eight rows of blades. 



All this blading was refitted completely, amounting in all to about 13,500 blades 

 and packing sections, and the turbine was closed up on September 25. 



On October 7 this turbine was coupled up to the low-pressure ahead and both 

 revolved by the turning gear in ahead and astern direction, and everything was 

 found to be in order. 



Lotv-Pressure Astern {Starboard Outboard) : — 



Rotor. — (a) The first four rows at the steam inlet end and the last row at the 

 exhaust end were badly damaged. 



{b) A pocket about 16 inches wide had been cut through the last seven rows 

 of blades at the exhaust end. 



