278 ELECTRIC PROPULSION OF MERCHANT SHIPS. 



applied to such a ship, and, for comparison, an equipment with triple-expansion 

 engines is shown in Plate ii8. It will be observed that in this design the motor is 

 placed as far aft as convenient, affording space for disassembling and for removal 

 of the tail shaft. The generating unit and controlling equipment are placed near 

 the boilers in such a manner as to afford a maximum convenient saving of cargo 

 space, the condenser being suspended below the turbine in the same compartment 

 with boilers. The auxiliaries are distributed in convenient locations in the turbine 

 room and in the space below near the condenser. 



The weight of this equipment, including generating unit, motor, controlling 

 mechanism, and direct current exciter, will be about 67 tons. 



Auxiliaries. — In connection with such equipments it is proposed to use, as 

 much as possible, electrically driven auxiliaries. It is necessary to maintain an 

 electrical supply independent of the main generator for purposes of excitation and 

 lighting. The losses involved in the operation of larger auxiliary generating equip- 

 ment are relatively much less, and there is no increase of complications. With 

 such an equipment it is proposed to install two 1 50-kilowatt, turbine-driven, di- 

 rect-current auxiliary generating units, one being required for service and the other 

 installed as a spare. Excitation and lighting will only amount to 40 kilowatts, leav- 

 ing 1 10 kilowatts available for any possible auxiliary uses. A little more than half 

 of this should be sufficient for normal conditions. While the ship is at sea, for rea- 

 sons of simplification and economy, it is proposed to exhaust the auxiliary generat- 

 ing unit into one of the lower stages of the main turbine at a pressure somewhat 

 above the atmosphere, so that some of this exhaust steam will be available for feed 

 heating if that obtained from steam-driven auxiliaries is insufficient. In port these 

 auxiliary units would be exhausted into an auxiliary condensing plant which would 

 be idle while the ship was at sea. 



Motor Compartment. — The motor carries the thrust bearing and is also 

 equipped with a simple, slow-moving oil pump which maintains automatic lubrica- 

 tion in the motor compartment. This lubrication can be arranged with a storage 

 tank and with an emergency drip supply to the low-speed bearings contained in the 

 after compartment, so that, even if the oil pump should fail, many hours might 

 elapse before injury could result to any of the bearings. With such an arrange- 

 ment the self -lubrication of this compartment becomes entirely simple and safe, 

 and with occasional inspection it should be operated without an attendant and with- 

 out any passage connecting it with the engine-room ; in fact, there is nothing that 

 an attendant can do in this compartment, and there would be quite as much reason 

 for keeping an attendant on the truck of an electric locomotive where the electrical 

 and lubricating conditions are far more complicated. 



Space Saving. — It will be observed that the omission of the shaft alley and 

 the diminution of space required for the engine-room materially increases the cargo 

 space and simplifies its shape. This increase amounts to something over 12,000 

 cubic feet, nearly 3 per cent of the total capacity of the ship. The omission of the 

 shaft alley, shafting, and supporting bearings effects a weight saving of about 60 



