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Colonna's Shipyard Inc. (ID: 881)
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Charles J Colonna, Colonna's Founder, designed and built his shipyard just ten years after the War Between the States.His marine railway had a 50 ton lifting capacity and the cradle was pushed up a 4 inch wide wooden track. The railway was powered by one or two horses, depending on the weight of the vessel hauled. The cradle of a railway dry dock is a structure of unique design in that it must have strength and stability and yet at the same time be flexible in longitudinal bending and in torsion to accommodate the irregularities of the track and the ship. Varying local conditions and dry docking requirements affect the type of dry dock best adapted to meet these requirements, be it railway dry dock, floating dry dock or basin dry dock. Hauling machines of railway dry docks have been developed for this particular use. Each consists of a train of gears, usually operated by steam or electric motors, turning one or more toothed chain wheels driving the hauling chains. Electric protectioh has been incorporated in hauling machines to avoid damage when either operating in reverse against the stop pawl, or forward with the cradle against a head wall. This is extremely important, since replacement of large gears will take several months. The use of automatic brakes in our modern hauling machines protects against cradles running away, due to human failure or electrical failure. Enclosed oil bath speed reducers are being used to eliminate unnecessary noise, danger of open high-speed gears and to insure adequate lubrication with maximum cleanliness. Many steam-operated hauling machines have been converted to electric drive. The electric motor permits the use of electric brakes, limit switches and overload protection, Each hauling chain is arranged, in conlunction with a smaller 'backing chain," in an endless system attached to the cradle. The hauling chain passes around its chain wheel and the backing chain through a submerged sheave. which steam does not normally provide. Also, the electric drive eliminates the need to fire boilers, prior to operation. The steam driven machine still has the advantage of a wide range of speeds and independence from electric power supply. If the railway has a roller system which is in good condition and its chains are properly supported, it is possible to eliminate cradle surging by increasing the hauling speed of the machine. Naturally, the increased speed will require greater horsepower. On the other hand, this increased speed will reduce the hauling and lowering time for the cradle. For small installations air motors have been successfully used, but these are very ineflicient and should be limited to yacht railways. Six-Chain Electrically Operated Railway Dry Dock Hauling Machine We're working hard to bring you an ongoing look at the projects being accomplished by the professionals at Colonna's Shipyard. Since 1875, Colonna's Shipyard has been providing full-service ship repair. Strategically located on the banks of Virginia's Elizabeth River,Colonna's deep water facilities can undertake a wide range of repair jobs for ships up to 800 ft. We're working hard to bring you an ongoing look at the projects being accomplished by the professionals at Colonna's Shipyard. Colonna's Shipyard Inc.