Engineering Wonders of the World
Volume III

REMARKABLE MACHINERY. ends of the largest furnaces are operated hydraulically. Coming to actual figures, we may mention that the rolling portion of a 250-ton capacity furnace weighs, with its charge, about 1,000 tons. One of the greatest im- provements in steel-works’ practice was the introduc- Wellman, of mach inery for charging the open hearth fur- nace, and thereby greatly reducing the wages bill while increasing the output Mechanical Furnace Chargers. from the furnaces. Under the old system pigs of iron were fed in one at a time by an implement something like the “ peel ” with which a baker places loaves in his oven and withdraws them. A modern charging- machine will feed in four tons of iron—about 100 “pigs”—at once, at the rate of a load in forty seconds. One man suffices to work the machine, and one is needed to open and close the furnace door. These mechanical chargers are constructed to move either upon rails on the charging platform, or upon overhead runways. We select for detailed description a machine of the second type, as being the more interesting mechanically. At the top is a wheeled girder carriage resting on the runway. Across the carriage, towards and away from the furnaces, travels a trolley, from which depends a structure con- taining a vertical sliding mast. To the bottom of the mast is pivoted a charging-bar, carrying at the end either a box for pigs or a peel for large masses of iron weighing up to eight tons. The bar can be moved vertically and horizon- tally, and be rotated about its own axis, in- dependently of the motions of the trolley 267 TAPPING AN OPEN HEARTH FURNACE. and main carriage. The operators become so skilful as to move the bar in three senses at the same time. To charge the furnace, the box or peel on the bar is loaded ; the furnace door is opened ; the bar passes in and re- volves, depositing its load on the hearth. These machines are worked by very power- ful electric motors and controlled by strong brakes, and so are able to start and stop very quickly. Ihe molten steel, by whatever process made, is always teemed, before being cast, into ladles which are in many cases handled by electric overhead cranes. Some cranes are able to work Cranes, ladles containing 60 tons of molten metal. Their chief feature is a main trolley running on two parallel girders and provided with two sets of motor-operated lifting gear, the chains or ropes of which hang down outside the girders. The ropes or chains support a heavy cross-beam and hooks for holding a ladle. An auxiliary trolley, moving on rails between the girders, and running from end to end, is used to tip the ladle and to lift light loads. For rope suspension as many as sixteen falls of rope in four separate cables are