. Elements of transportation, a discussion of steam railroad electric railway, and ocean and inland water transportation . Side Lever Type of Marine Engine. all ocean liners. Double screws were used on war vesselsbefore they were on merchantmen. The Development of the Marine Engine.—The marine en-gines now in use are of two general types: the reciprocat-ing and the turbine. The reciprocating, which is still themore usual form of engine, is one which drives a pistonback and forth; whereas the turbine engine drives or re-volves a drum or shaft in one direction. The reciprocating 212 ELEMENTS OF
. Elements of transportation, a discussion of steam railroad electric railway, and ocean and inland water transportation . Side Lever Type of Marine Engine. all ocean liners. Double screws were used on war vesselsbefore they were on merchantmen. The Development of the Marine Engine.—The marine en-gines now in use are of two general types: the reciprocat-ing and the turbine. The reciprocating, which is still themore usual form of engine, is one which drives a pistonback and forth; whereas the turbine engine drives or re-volves a drum or shaft in one direction. The reciprocating 212 ELEMENTS OF TRANSPORTATION engine has had an interesting technical evolution. Only afew of its main types will be referred to here. The first Cunarders and the other early ocean steam-ships had what were called side-lever engines, which werelike the walking-beam engines, still seen on ferry boats,except that the beam was not placed above the cylinderand wheel shaft, but below and at the side, as is shown inthe illustration. When the screw propellers came into use,. Geared Beam Engine, Constructed in 1855. it was necessary to increase the speed of the revolutionof the shaft, and to accomplish this the geared engine wasintroduced, i. c., an engine which drove a large cog wheelthat geared into a smaller wheel that revolved the pro-peller shaft. The general arrangement of the gearcd-hcamengine is shown in the illustration. Another geared enginefrequently used was tlie one with oscillating piston in this on<!:ine was connected directly withthe crank shaft and as the crank revolved the entirecylinder oscillated upon its central axis of sui)port. The THE STEAMSHIP 213 general design of such an engine is indicated by theillustration. The gearing of the engine caused loss of power; andfi-oni the time the screw propeller was introduced, effortswere made to perfect a direct-acting engine. It was diffi-cult at first to do this, because the vessels were not wideenough to permit the e
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