ELECTRIC PROPULSION OF MERCHANT SHIPS. 297 



Mr. Fernald spoke of my optimistic views concerning gears in, electric drive. It will 

 never do the gears any good to try to explain that trouble does not exist. I think and hope 

 that gears can be made, that we will make them big enough to stand up; but the point is 

 that the record to date has not shown it, and they must be made bigger. If made bigger, 

 it is harder to make them compete with the electric drive. In the first place, the bigger 

 gears are less efficient; they cost more and weigh more. 



The matter of air supply has been mentioned and the difficulty of possibly getting salt 

 water into the machinery. One experience we have had on board ship is that we get much 

 cleaner air. Carbon dirt and metal dirt which come out of the streets of a city is what 

 bothers us in generators. In the case of the battle cruiser, which is by many times the 

 largest electrical job ever done in the world — in the case of building the machinery for these 

 battle cruisers, we are not talking the air from outboard. We are going to circulate the 

 air locally and cool it and use it over again, we carry it through coolers somewhat similar to 

 the way in which it is done in the case of automobile radiators, and it may be done in a very 

 surprisingly compact space and with a very slight increase in the running temperature of 

 the motor, and the motor will be cool at all times, except when the ship is in very warm 

 water. This is entirely practicable, and is a tremendous simplifier in the application of this 

 machinery to a warship, for the reason that the difficulty of getting these immense ducts in 

 and out of the machinery space is very great ; besides, there is very great risk in the impair- 

 ment of ventilation by damage to these ducts, or danger to the ship by water going down 

 them in case they are damaged by gunfire or other causes. 



As to the matter that Mr. Allen mentioned concerning tooth pressure, he implied that 

 our designs had been criticised before we made them. But I do not think that he meant 

 that. As a matter of fact, no such question ever arose that I know of — they were running 

 ships for a year and a half, and praises were being showered on us in regard to the per- 

 formance of the gears before we knew we were in trouble or had any idea of it. The trouble 

 came all at once, and very rapidly, when a large number of ships began to navigate the 

 Atlantic at the beginning of the war. Of course, if we could have foreseen that, we would 

 have made the gears a great deal bigger, but we would not have known at any time how big 

 to make them, and I do not know today how big we would have to make them, but maybe, 

 if we made them big enough, it would be all right. 



Mr. Elmer A. Sparry, Member (Communicated) : — As usual, Mr. Emmet, in his 

 paper, "Electric Propulsion of Merchant Ships," has given us much food for thought. It 

 is true that, in the installation and operation of new machinery of almost any kind, unfore- 

 seen problems arise. The problems connected with reliability of gears used in ship propul- 

 sion are very perplexing. These gears are produced by different makers on both sides of 

 the Atlantic. They are designed with a wide range of tooth velocities and tooth loads. 

 Some have been very successful and others have given serious trouble. The trouble seems 

 to be so indiscriminately distributed among the different makes as to baffle analysis. Gear 

 sets of identical make, and seemingly under identical installation conditions, are divided be- 

 tween the very successful and the very unsuccessful. • Some of these gear sets give serious 

 trouble. 



It is known in the engineering profession that nothing of this kind happens without a 

 reason, and usually the greater the mystery which surrounds the difficulty the greater and 

 more outstanding is the reason when it is finally run down and located. In solving some of 



