DISCUSSION ON MAY MEETING PAPERS. 33 



In general, our comparisons between geared turbines and Diesel engines, and our con- 

 clusions from them, are in close agreement with Mr. Warriner's figures. Briefly, our con- 

 clusions are that the turbine installation will give higher earnings for all ordinary voyages, 

 but for long voyages the Diesel engine will yield higher earnings. These conclusions are 

 based on present conditions and machinery, without regard to future developments, which 

 may be important. 



Our comparisons between geared-turbine and turbine-electric-drive machinery show 

 that the electrical installation is 90 per cent heavier, that the cost is about double, and that 

 the steam consumption is about 6 per cent more. These figures refer to the main propelling 

 units only. They include the main turbines, gears and pipe connections for the former. For 

 the latter, they include the main turbo generator, main motor, fans, exciter sets, switching 

 gear, etc. 



It is obvious from these figures that there is no economic advantage in the electrical 

 transmission. In this connection it seems rather futile to advertise and argue advantages 

 which are not substantiated by the facts. It may also be noted that this type of transmission 

 is not being fitted in British vessels, either merchant or naval. 



The efficiencies of reduction gears as determined by careful tests are of especial interest 

 in view of the conflicting statements which have been made recently in regard thereto, espe- 

 cially by advocates of electric transmission. It is evident from these tests that efficiencies 

 of 94 and 95 per cent, which have been gi^en for double reduction gearing, are entirely 

 too low for normal operating conditions. 



These tests confirm the tests and efficiency values which have been given by the Par- 

 sons, De Laval, and Westinghouse companies. 



For normal operation under the usual conditions the reduction gear losses may be safely 

 taken from 1% to 2j4 per cent for a single reduction gear, with 2 per cent as an average 

 value. For double reduction gears they may be taken from 2^ to 3j4 per cent, with 3 per 

 cent as an average value. (Applause.) 



Mr. Alexander Schein^ Member: — Mr. Warriner, in his paper, has presented us 

 with very valuable data and numerous suggestions for securing successful operation and has 

 pointed out important requirements to be considered when designing reduction gears. 



I must use again the same paragraph that Mr. Smith used, but I think our deductions 

 are rather different. On page 16 the author refers to the following : "The conditions at 

 sea, however, are entirely different, and it is difficult to estimate what may have to be taken 

 into account." In conjtmction with this, I wish to take the liberty of pointing out a very 

 interesting experiment which was carried out on the S. S. Coronco sometime during the past 

 winter, an account of which was given in several of the technical periodicals. 



A test in measuring the distortion of the reduction gear casing was carefully carried 

 out under various conditions of the wind and for different headings of the vessel. The 

 results clearly indicate that either rolling or pitching causes a very marked distortion of the 

 gear casing. However, a combination of roll and pitch results in the greatest distortion and 

 accordingly the greatest misalignment in teeth at the line of their contact. 



No doubt some of the distortion of the gear casing is not only due to the ship's defor- 

 mation under severe action of the sea but also due to the inertia of the oscillating masses that 

 are in continuous cycles of acceleration and deceleration in synchronism with the roll of the 

 vessel. This action is more pronounced in twin-screw vessels. 



