DISCUSSION ON MAY MEETING PAPERS. 23 



methods of burning the fuel, and rotational speeds up to 1,500 revolutions per minute are 

 perfectly practicable and have been demonstrated. The engine is high compression and 

 auto-ignition. 



This new engine is not limited to the use of the higher priced Diesel oils but runs on 

 the cheapest grade of boiler fuel oil. It does this without the use of a spray air compressor. 

 The combustion chamber being about 30 per cent of the piston displacement and approaching 

 a hemisphere in shape, makes possible the use of the simplest form of solid injection system. 



It will be seen from the above statements that a real, serious attempt is being made to 

 produce a light, compact and efficient prime mover, the commercial introduction of which will 

 mark an epoch in the development of the Diesel engine in this country. This engine is in 

 an advanced stage of development, and commercial construction on several applications is 

 already under way. 



In connection with the development of this engine, and in order to provide any Diesel 

 type of engine with speed flexibility approaching that of the steam engine, there has been 

 developed an electro-magnetic clutch operating on an entirely new principle, rugged in design 

 and construction, consisting of but few parts and capable of being built to transmit practically 

 any range of horse-power. This new type of clutch transmits torque entirely through air 

 gaps and has no mechanical contact whatever between the driver and driven. It is capable 

 of remote control and may be operated at any speed from zero to full engine speed, the 

 torque being imder full control. The power required to operate the clutch at full load is but 

 a fraction of 1 per cent of the power transmitted. On direct drive the clutch has a unique 

 feature of being magnetically locked together and transmits full engine power without slip 

 and with an enormous increase in pull-out torque. 



Mr. Benjamin G. Fernald, Member: — This discussion was prepared jointly by my 

 associate, Mr. C. O. Tappan, who is not a member, and myself. 



The Society is to be congratulated on having secured the presentation of these two papers. 

 The authors of both papers occupy a leading position in the marine engineering field and are 

 connected with companies which either build or furnish all types of propelling machinery, 

 and are therefore well qualified to discuss the subject authoritatively and without bias. 



Relative to Mr. Warriner's paper, we are in substantial accord with the author's conclu- 

 sions throughout, and our only criticism of any of his statements on the foregoing points 

 is that in the last paragraph of page 14 he limited his imputation of "lack of knowledge of 

 gears and their requirements" to the engine-room stafif. In our opinion the trouble experi- 

 enced with marine reduction gears was due as much to "lack of knowledge of gears and 

 their requirements" on the part of the designers and constructors as to the operating staff, 

 although the latter certainly contributed their quota. It would be possible to discuss the 

 whys and wherefores of gear troubles at sufficient length to fill a volume of the Society's 

 transactions ; however, we believe that those who have been in close touch with the situation 

 are satisfied that geared turbines of both the single and double reduction type, which will 

 operate with reasonable reliability and quietness, are now procurable for any type of vessel 

 for which such equipment could be considered. 



The ultimate efficient life of reduction gears is not as yet established, and we believe 

 it is doubtful if either turbines or gears of any type can be expected to furnish useful service 

 for such periods of time as slow-speed reciprocating engines. This deficiency, however, could 

 be taken care of by applying a more liberal amortization percentage to such installations 

 when comparing them with more durable types of propelling machinery. 



