Screw-propeller steamers Steamship

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francis pettit smith 1836 patent propeller design fitted archimedes.


the key innovation made ocean-going steamers viable change paddle-wheel screw-propeller mechanism of propulsion. these steamships became more popular, because propeller s efficiency consistent regardless of depth @ operated. being smaller in size , mass , being submerged, far less prone damage.


james watt of scotland given credit applying first screw propeller engine @ birmingham works, steam engine, beginning use of hydrodynamic screw propulsion.


the development of screw propulsion relied on following technological innovations.


steam engines had designed power delivered @ bottom of machinery, give direct drive propeller shaft. paddle steamer s engines drive shaft positioned above waterline, cylinders positioned below shaft. ss great britain used chain drive transmit power paddler s engine propeller shaft - result of late design change propeller propulsion.



image of stern tube , propeller shaft in lighthouse ship.


an effective stern tube , associated bearings required. stern tube contains propeller shaft passes through hull structure. should provide unrestricted delivery of power propeller shaft. combination of hull , stern tube must avoid flexing bend shaft or cause uneven wear. inboard end has stuffing box prevents water entering hull along tube. stern tubes made of brass , operated water lubricated bearing along entire length. in other instances long bush of soft metal fitted in after end of stern tube. great eastern had arrangement fail on first transatlantic voyage, large amounts of uneven wear. problem solved lignum vitae water-lubricated bearing, patented in 1858. became standard practice , in use today.


since motive power of screw propulsion delivered along shaft, thrust bearing needed transfer load hull without excessive friction. ss great britain had 2 ft diameter gunmetal plate on forward end of shaft bore against steel plate attached engine beds. water @ 200 psi injected between these 2 surfaces lubricate , separate them. arrangement not sufficient higher engine powers , oil lubricated collar thrust bearings became standard 1850s. superseded @ beginning of 20th century floating pad bearing automatically built wedges of oil withstand bearing pressures of 500 psi or more.








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