286 ELECTRIC PROPULSION OF MERCHANT SHIPS. 



mechanically than pipes and mechanical motions, etc." This might be considered so by 

 some people, but others think differently. Steami leaks are much easier to locate and repair 

 than short circuits or electric leaks, and steam-driven auxiliaries are easier to repair than 

 those driven by electricity; furthermore, the former is less likely to be damaged by water 

 than the latter. No' more skilled labor is necessary to make repairs, on a ship fitted with 

 geared turbines or reciprocating engines, than is required on one fitted with the electric 

 drive. Conditions existing in mills, mines, railroads and other industries are so different 

 from those on board ship that any comparison would be useless. 



Anyone reading the description of the U. S. S. Jupiter and New Mexico would not be 

 of the opinion that the electric machinery used to propel a ship is simpler than that used for 

 lighting, nor would they think it simpler than a geared turbine or reciprocating engine. 

 The U. S. navy colliers fitted with reciprocating engines and geared turbines were oper- 

 ated before the war with merchant crews most of the time, while the Jupiter has always 

 been operated by a navy crew. 



Mr. Francis Hodgkinson (Communicated) : — Mr. Emmet's paper undertakes to de- 

 scribe an electric drive installation for an 8,800-deadweight ton ship of 2,500 horse-power. 

 In the text of the paper he refers to tooth gearing and compares them to their disadvantage 

 with electric drive. 



Mr. Emmet paints a picture of gear troubles and their failures, entirely neglecting to 

 make it clear that he referred to the type of gearing, the manufacture and design of which 

 he had been associated with, and did not refer to those of any other type. 



Mr. Emmet referred to cases of gear trouble which he stated was due to the teeth 

 being overloaded. In the whole of my experience I know of no case of Westinghouse gears 

 where there has been a single failure which could be attributed to too high tooth pressures. 

 All the troubles which have l^een experienced have been understood and may be readily 

 avoided. Experiences during the last year indicate we are nowhere near the limits of the 

 possibilities of teeth gearing. Reference is made to the so-called "Standard English Ship." 

 being equipped with double reduction gearing, and a statement made that single reduction 

 gears are being advocated and applied in this country for a ship of the type referred to 

 in the paper. It is true that single reduction gears have been advocated in this country for 

 installations for which double reduction gears are the more appropriate, which can only be 

 attributed to misapprehension and lack of understanding of the gear problem. No gear 

 troubles whatsoever could be attributed to the fact of the gears being double reduction. On 

 the contrary, the difficulty of accurately cutting a gear of large diameter with its possibili- 

 ties of distortion render the double reduction gear the more desirable and is far more eas- 

 ily installed. Presumably Mr. Emmet is relating his experience with the particular type of 

 gear his company has exploited, and which we understand has proven quite unsatisfactory. 



He refers to the uncertainty of gear operations in ships and their being so much less 

 durable than gears on shore. So far as our experience is concerned, there is no differ- 

 ence, but of course it must be reckoned with that misalignment is to be encountered on 

 board ship, and I would not regard any gear as satisfactory for a marine installation unless 

 it were capable of operating perfectly well with the changing position of a hull. Plainly 

 the type of gear with which Mr. Emmet is experienced is unable to conform to such varia- 

 tions as can the well-known floating frame gear, and local concentrated tooth pressures will 

 occur which may readily be destructive. 



