42 DISCUSSION ON MAY MEETING PAPERS. 



A flexible shaft with gearing- was used in the first Melville and Macalpine gear built 

 in 1909 and has been used by the Westinghouse Company ever since. 



We would like to add something to the information available with regard to gear 

 efficiency. The Westinghouse Company conducted a large number of tests on a pair of 

 1,500 horse-power double-reduction gears designed to be driven by a single, complete ex- 

 pansion turbine. These gears were coupled together, and the high-speed pinion of one 

 driven by a carefully calibrated steam turbine, and the high-speed pinion of the other 

 was connected to the water brake. Readings were taken, over a wide range of load and 

 speed, of the steam conditions on the turbine and the horse-power absorbed by the brake. 

 The turbine was then again directly connected to the brake and the horse-power mea- 

 sured under identically the same steam, conditions as when operating with the gears. Suffi- 

 cient observations were made so that the errors of observation could be corrected by 

 means of suitable curves. The accompanying curve (Plate 11) shows the net result of these 

 tests corrected for a single double-reduction gear. These tests check quite closely with those 

 reported by the author, although we believe the light load efficiency should be somewhat 

 higher, as indicated on this curve. 



Another test was made in a similar manner on a pair of 5,000 horse-power double- 

 reduction gears designed to be driven by a cross-compound turbine (Plate 12). These tests 

 show an efficiency at full load and full speed of 97 Y^ per cent. The tests on the 1,500 horse- 

 power gear indicated that the loss in power in this gear could be very nearly approxi- 

 mated by the formula : 



„ ^ , VH. P. load X R. P. M. 



H. P. loss = —i-^ 



60 



R. P. M.= revolutions per minute of high-speed pinion. 



A pair of 15,000 horse-power single-reduction gears for destroyers was tested in a 

 manner similar to that shown on plate 7. A 1,500 horse-power turbine was used for a 

 drive through the third gear of the same type as those tmder torque, but unfortunately the 

 power required to drive this equipment at full speed was so light that it could not be accu- 

 rately determined on this turbine. A careful estimate indicated about 500 horse-power for 

 the two gears under load and the one gear running with that amount of load at full speed, 

 giving a net probable efficiency per gear of 98J/2 per cent or better. (Applause.) 



Mr. L. V. Armstrong, Me-mber: — With reference to the paper by Mr. Metten and 

 Mr. Shaw, it is interesting to note that the Ingersoll-Rand Company, after approxi- 

 mately fifty years of successful building of air-compressing machinery when they decided 

 to enter the oil-engine field, saw fit to reject the licenses of certain well-known air injec- 

 tion Diesel engines and adopted a mechanical injection engine. They certainly must have 

 had some very good reason for doing this. 



Mr. Hubert C. Verhey, Member (Communicated) : — ^The critical analysis as tabu- 

 lated in the paper of Messrs. Metten and Shaw is worthy of notice and should arouse in- 

 tense interest as coming from men with acknowledged experience in marine steam 

 installations. 



From actual and practical personal experience obtained during a trip to the Orient 

 and return on board of one of the modern vessels as described in the paper, I may declare 



