The Works Of Messrs. Schneider And Co.

STATIONARY ENG-INES. 111 The Corliss inlet valves have been replaced by balanced cylindrical slide valves, with alternating rectilinear motion. These slide valves are double ported, as also are the exhaust valves. The engine is horizontal, working a crankshaft that rests on two bearings cast in one piece with the foundation plate ; the engine is therefore self-contained, and easily transported and erected. The foundations required are not of great importance. According to circumstances, these engines work the dynamos either direct or through Inter- mediate transmissions, and in order to drive two dynamos, the crankshaft carries a flywheel pulley at each end. The governor is fitted inside one of the flywheels, according to the American principle ; it consists of two weights balanced by two helical springs, which act on the eccentric that works the admission slide valves by modifying the stroke, the lead at the admission remaining practically constant. In order to simplify lubrication of the governor, and to keep it free from dust, all the mechanical parts are closed in. The special eccentric that moves the exhaust valves is fixed and keyed on the motor shaft. The cylinder body, bottom, and cover are steam-jacketed. A standard type of this engine, when running at 250 revolutions, can develop on the piston 200 indicated horse-power, with a steam pressure of 7 kilogrammes (99.561 Ib. per square inch). This represents a piston speed of about 4.150 metres (13 ft. 7f in.) per second. A long series of experiments have been made with these engines, especially as regards the regularity of working and the consumption of steam. The former quality leaves nothing to be desired. The governor is so sensitive that the speed is maintained almost constant, the variations being below 2 per cent., and the greatest variations in the loads producing hardly any oscillations. Consumption trials have been made with a non- condensing engine, working dynamos under a constant load. These varions trials lasted each a minimum of six hours, and gave excellent results as regards efficiency. We need not enter into the details of these trials, and shall simply state the following figures : Initial Pressures on Steam Piston. 5.300 kg. = 73.382 Ib. per sq. in. 6.200 „ = 88.183 7.000 „ = 99.561 8.000 „ = 113.784 Steam Consumption per Indicated Hokse-Power per Hour. 12.350 kg. = 27.227 Ib. 11.450 „ = 25.243 „ 10.950 „ = 24.140 „ 10.350 „ = 22.817 „ With condensing engines the above figures of steam consumption would be reduced by 15 to 20 per cent. Rolling Mili Engines.—The vertical Corliss engine, which is illustrated by Figs. 314 to 318, Plate LXVIIL, was designed in the Construction Department to work a series of rolling milis. Owing to the small space available, Messrs. Schneider and Co. were obligée! to adopt a vertical type. A certain number of these engines have been built by them for their own rolling mille and for rolling mills in Russia. They have one steam cylinder, the steam distribu- tion being on the Corliss system, and the four valves and gear being arrangée! in the same way as with the horizontal Corliss engines built at Creusot. The condenser air pump is vertical, single-acting, and is worked by a cast-iron beam fitted to the top of the steam piston-rod. Two floor plates give free access to the varions parts that require attention and lubricating. The four frames that carry the steam cylinder, and on which are fitted the slides, are hollow and of rectangular section. They are firmly secured to the foundation plate, which also carries the motor shaft plumber-bloek ; they are, moreover, firmly secured together. When running at a speed of 70 revolutions, which Messrs. Schneider and Co. have adopted for various installations, they work very satisfac- torily and develop under the most advantageous conditions from 900 to 1,000 horse-power. The steam cylinder is 1 metre (39j in.) in diameter, the stroke being 1.600 metre (63 in.). These vertical engines for high powers and speed are mueh in favour at Creusot ; they give great satisfaction as regards wear of steam cylinder, piston, glands, and rods ; their first cost, however, is higher than that of horizontal engines of equal power. Steam Draining Pumps.—Messrs. Schneider and Co. put down in 1869 at their St. Laurent pit (see pao'e 14, ante) a steam draining pump to discharge all the water from the lowest deptbs of their Creusot coal mines. The water is lifted from a depth of 420 metres (1,378 ft.) at the rate of 150 cubic metres (5,298 cubic feet) per hour. The engine placed at the pit’s mouth is on the Woolf system, with two single-acting cylinders, variable expansion, and is provided with a condenser. The large cylinder piston is connected direct to the main pump rods, which works the shaft pump placed at the bottom of the pit, and the series of five forcing pumps placed one above the other down the pit shaft. The main rod is of wood strengthened by fiat iron bars. The total résistance to be overcome lifting the water, added to frictional losses, amounts to 88 tons. The total weight of the rods and plungers, with their accessories, plus the columns of water in the pumps, amounts to 148 tons. To counterbalance the difference between this weight and the forcing résistance, two corn- pensating pumps have been erected in the shaft on the top levels, and a counterweight has been placed at the end of the lever beam, opposite the end which holds the plunger rods. The stroke in the smaller cylinder is 2 metres (6 ft. 6|£in.); that in the expansion cylinder, which is also that of the whole series of pumps, is 4 metres (13 ft. in.). The speed is 3| strokes per minute. The duration of admission in the small cylinder varies from /o0« to the total stroke, according to the steam pressure. x