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Tanker Herman Falk—Single Screw—Twin Geared Diesel Drive—Owned by Oil Transport Co. Geared Diesel Drive Installed Two 8-Cylinder Engines Geared to Single Propeller Shaft in Tanker Herman Falk—Vessel in Service Operates with Success N ORDER to obtain maximum | propeller and_ hull propulsive efficiency it is necessary to keep the propeller revolutions comparative- ly low. In other words for the usual type of cargo ship, if it were con- veniently possible to do so, the idea! number of revolutions would be _ be- tween 70 and 80. For a direct con- nected drive it is not possible for certain types of motive power to keep the revolutions at so low a _ point. This obviously applies with great force to the turbine. It also applies with much less force to the diesel engine. However, the builders of diesel engines recognizing the require- ments of the naval architect have turned out slow speed engines in or- der to furnish power to the propeller at speeds that will approximate maxi- mum efficiency. The road to reduction in weight and higher engine efficiency unquestion- ably lies along the line of increased speed. This is clearly demonstrated by the wonderful development of in- ternal combustion engines for the automobile and the airplane. As long as the marine engine builder is re- stricted to the comparatively low rev- olutions for his engine which is re- quired for maximum propulsive ef- ficiency when it is direct connected to the propeller there is little oppor- tunity to reduce weight and to im- prove the efficiency of the engine it- 20 self. Consequently in order not to restrict either the engine builder or the naval architect in their respective requirements much work has_ been done in developing means of speed reduction between the engine and the propeller. A number of vessels, from small river boats to ocean tankers have been fitted with diesel electric drive where comparatively light high speed engines are direct connected to electric generators. The current so generated is then applied to an elec- tric motor direct connected to the propeller. In this case a very defi- nite variation of speed is possible for the propeller and it can be arranged to have maximum power delivered at ideal propeller revolutions. A Practical Reduction Gear Though possessing many advan- tages, there are certain objections to the use of electric power in this manner solely for speed reduction. In other words engineers recognize that if it were possible to obtain speed reduction by mechanical means of absolute reliability that this would serve the purpose where the matter of speed reduction alone is the de- termining factor. It was to solve this problem that the Falk corpo- ration with many years of experience in gear design and construction after a long period of study and prelim- -inary development work offered the interesting twin diesel engine reduc- tion geared drive now installed and in service in the tanker, HERMAN FALK, owned by the Oil Transport Co., Baltimore. The work was carried out at the CROSS SECTION—FALK DIESEL ENGINE Sparrows Point plant of the Bethle- MARINE REVIEW—December, 1927