The Works Of Messrs. Schneider And Co.

116 MESSRS. SCHNEIDER AND CO.’S WORKS. for air, and provided with valves within easy reach of the workmen, for regulating the blast. Four electric travelling crânes, constructed ai Creusot, one of 20 and three of 5 tons, serve the shops from one end to another; these crânes are illustrated by Figs. 332 to 334, Plate LXXV. The overhead tracks, formed of cross girders, are carried on one side by the columns, and on the other by stanchions built into the walls. The electi’ic travelling crânes take direct current, at 220 volts, by means of carbon brushes, which slide on naked conductors supported along the track by porcelain insulators. The varions movements of each travelling crâne are independent one from the other ; a dynamo works each one, the movement being controlled from a cabin for the 20-ton ci’ane, and from the floor level for those of 5 tons. The lifting speed can be varied within certain limits, suppliée! at 220 volts by a generating station situated near | the electric construction works. This station, which also supplies current to the ordnance works, contains engines of 700 horse-power in ail, but it was designed with a view of increasing to 1000 horse-power. The overhead uninsulated line ends on an iron standard fixed to the roof of the electric construction works. The lighting of the works is insured by low-tension alternating currents, supplied by transformers which receive the current from the central lighting station above mentioned. The arc lamps which are used are o£ 30 volts and 12 amperes; they are placed along the walls and against the columns, at intervals of about 10 metres (32 ft. 10 in.). They are branched on 50-volt circuits, and a self-induction device placed in series with each lamp absorba the excess current, with hardly any Fig. 331. Plan of Electrical Construction Department. according to the load and the manœuvres required. For lowering loads, the corresponding dynamo is short-circuited under a résistance that can be regulated, thus enabling the speed to be controlled. The handling of these travellers is very simple, and they are foiind quite satisfactory. As they contain hardly any wheel gearing, there is practically no noise or vibration, even when ail the crânes are working simultaneously. Several two-phase current dynamos, which drive varions shafts and machine tools, are supplied from a 2000-volt generating group, situated in the central lighting station 2 kilometres distant. The bare wires which conduct the current are supported on iron columns and run to the primary coils of transformers, placée! in the electric con- struction shops, where the current is reduced to 110 volts, at which it is taken up by the motors. The current necessary for the travelling crânes and other motors, is expenditure of power. Incandescent lamps of 16 candies, on the 110-volt circuit, and provided with metal screens, supplement the lighting. The incandescent lamps for lighting machine-tool work, are made portable. Before final delivery, ail the machines undergo tests, according to the conditions under which they will have to work. These tests are made in a laboratory which adjoins the shops, and which is fitted up completely with ail the most modern appliances. Dynamos and motors are also tested in working, under conditions as near as possible normal. Insulation and overcharge tests are fully carried oui, and the machines are only delivered when ail the tests have been satisfactory. Dynamos and other machines, after testing, are fitted up and painted, and a final test, on the spot, with no load, furnishes the proof that they have been re-erected with ail due care. Much attention is given