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Online Encyclopedia
Originally appearing in Volume V24, Page 964 of the 1911 Encyclopedia Britannica.
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O'. 0000 oli' °" oil oil fj 0 0 0 Oi; 0 0 0 9gO io; o O O ~~ • O O 0 0 ,011 0'; o OO 0:01:0 0 0 o o 1: o o O O O lo :o 0 O o o ;o;; 0 0 0 0 , ,p-O o 19.0.0 :O-," O b O-' '"•__-_iO„O - .._% O O ~ O O Q O, OHO .O~ 0 O.O.,OF_O 'O --- -O I.O 0 0-O 000; d i °i' 0001 I 1 ivp'; PLAff M :C bOol-D . PLATS q: M ( n fah °II ° o o o o: toiln Outside i0:' Strake. 4, 0 0 0: '; - f 0001 i3O• to R I o o oi- .APFEp sun ti ,l Ol OI 0, O 000 101 O •01! -------0 b o o. o 0 o 0.' OoQQb o 00OoOt ooOo0 ,Oo000,;,OooOlO 0Oo00;O-Oo0 0 0 0 91010 0 0 0 0 " 6.0 _0 -o 0 I, 0 0 0 0 0 0 0 0 0 0 i00 0 0 0 0 .0ff; 0 O O 0 O t010 0 0 0 0:0 0 0 0 0 10 1 1t0J1 001 FOi: O;I 0 O O '0 !; ~l toll Inside o9 Strake, jo,j urPEo Tr~ 0 0: 000 1° to' i°,i o 0 0 Cranes . are to be found in these yards for the purpose. As an example mention may be made of the overhead cranes fitted at the Union Ironworks of San Francisco. A framework of wood is built up over the entire building berth, the structure being well braced in all directions for carrying two travelling girder cranes. There are four building berths fitted in this manner, and the latest has a length of 408 ft., a clear breadth of 8o ft., and clear height of 72 ft. A swing crane of 50 ft. spread at each end of the erection increases its effective length to 500 ft. Each of the travelling girders carries a trolley, with motion transverse to the ship; five tons can be so lifted, and parts of the ship's structure not exceeding this weight can be taken from the ground anywhere in the neighbourhood of the structure and conveyed to any desired spot in the ship. The driving power is electric. The longitudinal travel of the girders is 18o ft. per minute; the transverse travel of the trolley last two of steel. The largest is 700 ft. long. One trestle structure, or and speed of lift, each 90 ft. per minute. A manila rope is used for I gantry, serves two building berths, and runs longitudinally between AIL PRAMS loll Ol, c .. marked upon them before they are taken to the machines where arranged, being on the cantilever travelling-crane principle. There the shearing, punching, drilling, shaping, &c., are carried out, after I are five such structures in the yard; three of them are wood, the which they are taken to their proper position in the ship. _ ~Im In many shipyards great attention has been given E Section shewing Ordinary Type of Plating alp to the questions of the economical handling of the o material,and very costly and novel appliances Section shewing, Joggled Plating. Section shewing boggled Frames. the two. On the gantry is mounted a double cantilever crane, having an effective reach of 95 ft. on each side of the centre; this outreach is sufficient for a ship 7o ft. broad on each side of the trestle. The height of the cantilever above the ground is some 90 ft., the load that can be raised is 15 tons, and if necessary a bulkhead up to that weight can be lifted bodily into place. The speed of lift for this weight is ioo ft. per minute, and for lighter loads 700 ft. per minute. The speed of the trolley along the cantilever is 400 to 800 ft. per minute, and of the whole crane longitudinally is 400 to 700 ft. per minute. All movements are made by electric power. Similar gantries and arrangements are used in other American shipyards. The view shown in fig. 8o (Plate VIII.) represents one of these structures as fitted in Messrs Cramp's shipyard in Philadelphia. At the yard of Messrs C. S. Swan & Hunter, on the Tyne, similar structures have been erected since 1894; besides carrying cranes, these have standards and stiffening girders, from which ships under construction are shored for fairing. Roofs and sides are fitted to protect the ship, and the workmen engaged in building her, from the weather. The side supports are three in number, and serve for two berths; they are formed of steel lattice-work, with standards mostly 20 ft. apart. The clear height of roof is 83 ft., and clear breadth of berths 68 ft. and 73 ft.; a roadway on the ground level is left free on each side of the berths inside the standards. Two revolving 3-ton electric cranes travel along paths suspended from each roof ; their jibs have sufficient radius to lift material from the roadways and deposit it at the centre of the ships building. The longitudinal speed of these cranes is 300 ft. per minute; speed of lift, ioo ft. per minute. A third berth is served by a travelling cantilever crane on top of the adjoining roof. At Messrs Harland & Wolff's yard at Belfast another modification was introduced in 1897 (see fig. 81, Plate VIII.). In this case the structure takes the form of a travelling gantry or bridge over the building berth, the legs running on rails at the ground level. The gantry, which is driven by hydraulic power, has three traversing cranes and four 4-ton swing cranes. It was designed to facilitate the lifting of plates and portions of the structure into position, and also to support the hydraulic riveting machines and other appliances for the carrying out of the work. The success of the appliances, first used in the " Oceanic," has led to a further extension for other ships in hand.
End of Article: REVERSE

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