The Works Of Messrs. Schneider And Co.

ENGINES AND AIR COMPRESSORS. 113 pressure cylinders, the distribution is effected by four cylindrical valves of the Corliss type, without any device for varying the degree of expansion. AU these valves and connections work very smoothly, though they are of large size and comparatively quick-acting. Expansion in the small cylinders is regulated by hånd. A governor prevents the engines running at a higher speed than 72 revolutions ; moreover, in order to prevent an excessive strain on the working parts in case the air pressure should rise to a too high degree, a special governor slackens the speed when the pressure exceeds 8 kilogrammes (113.8 Ib. per square inch). These three means of regulating the engines, though independent one of the other, act on the same expansion device. The eccentrics that work the distribution valves, and the cams which act on the compresser valves, are fitted to a special sliaft, carried by the compressor lower valve chambers, and worked by the crankshafts through two vertical shafts and four sets of toothed wheels. Each engine is fitted with two flywheels, keyed to the crank- shaft couplings. The crankshafts of the four engines are placée! in the same line ; the frames that carry the steam cylinders and compressors, and to which are fitted the piston slides, are strongly fixed together by hollow cast- iron cross-beams. Three platforms of perforated plates, one above the other, and provided witli ladders, surround the engines, and give free access to all the mechanical parts. The whole of the condensera, air, feed, and drain pumps, are conveniently placed below the engine-room floor level, in a space 3.700 metres (12 ft.) deep, well lighted, and free of access. Each engine is provided with a condenser, placed in the same vertical plane as the large steam cylinder, and two vertical single-acting air pumps worked by east-iron balance levers fitted to the piston heads of the small and intermediate steam cylinders. The feed and drain pumps are placed on the air pumps, and are worked by crossheads fitted to the air-pump rods. Brass valves and india-rubber flaps are fitted in the compressor valve chambers, for the admission and delivery of air; these valves open freely, owing to the difference of air pressures, but are closed mechanically in order to prevent all shocks. Two of the three compressing cylinders draw in the air, and force it, in an intermediate wrought-iron reservoir placed parallel with the engines, and carried by cast-iron columns ; the third cylinder draws the air from the intermediate reservoir, inereases its degree of compression, and forces it in the main reservoirs of the works. Air is drawn in through the louvres on the roof ; these are in communication, through the box girders and hollow pillars that support them, with the low-pressure com- pressors. Special pumps, with valves worked mechanically on the Riedler system, independent of the main engines, deliver the water necessary for cooling the air in the compressors and intermediate reservoirs. The illustrations, Figs. 324 to 330, Plate LXXIV., show the detailed arrangement of these engines. The following are some further data concerning them : Normal power of each engine 2,000 2,000 ,, revolutions per minute horse-power. 60 horse-power. 60 Pressure of compressed air ... 8 kilogs. 113.8 Ib. per Steam pressure in bollers 12 kilogs. sq. in. 170.7 Ib. per Diameter of high-pressure steam cylinders ... ... .900 m. sq. in. 354 in. Diameter of intermediate steam cylinders 1.400 m. 55| in. Diameter of low-pressure steam cylinders 2.000 m. 1 78J in. Diameter of low-pressure compressors 1.100 Hl. 4;i| in. ,, high-pressure ,, Stroke ... .780 in. 30}} in. 1.400 m. I 55j in. Diameter of flywheels 5.500 m. 18 ft. ,, air pumps Stroke of air pumps ... 0.800 ni 31| in. 0.550 in. 21j in. Diameter of intermediate reservoirs 1.600 m. 63 in. Length of ,, ,, 9.000 m. 29 ft 6 in. Several efficieney and coal consumption trials have been made with these engines ; below are given the results obtained during one of them : Average number of revolutions per minute 59.635 59.635 Mean pressure in boilers Mean pressure at the high-pressure 11.050 kilogs. 157.2 Ib. per sq. in. cylinder valve Mean vacuum in condenser in centi- 10.290 kilogs. 146.4 Ib. per sq. in. metres of mercury ... 71.63 28^ in. f Low pressure Air pressure at J 2.300 kilogs. 32.7 Ib. per sq. in. compressors ) High ,, Temperature of air on entrance in 7.200 kilogs. 102.4 Ib. per sq. in. low-pressure compressors ... Temperature of air at outlet of high- 4.82 deg. Cent. 40 deg. Fahr. pressure compressor Mean ( Before passing through 20.6 deg. Cent. 69 deg. Fahr. temperature feed water heater ... of feed water ( A fter ditto 17 deg. Cent. 63 deg. Fahr. 60 deg. Cent. 140 deg. Fahr. Averagb Wokk on the Steam Pistons given by the Diagrams. High-pressure cylinder, top... ,, ,, bottom Intermediate cylinder, top ... „ ,, bottom Low-pressure cylinder, top ... „ „ bottom kilos. Ib. per sq. in. 3.025 43.0 3.055 43.4 1.203 17.1 1.209 17.1 .632 9.0 .572 8.1 Indicated Horse-Power on the Steam Pistons. High-pressure cylinder, top... ,, „ bottom Intermediate cylinder, top ... „ ,, bottom Low-pressure cylinder, top ... ,, ,, bottom Total indicated horse-power....... Rough coal consumed during the 8 hours’ trial ............. Slack and ashes „ ,, percentage ... Coal burnt during trial, difference ... ,, per hour ... Steam lost per hour through leakage and condensation ... CoiTesponding amount of coal lost per hour Amount of coal consumed per hour in working the engine Amount of coal consumed per hour and per indicated horse-power on , • , 1170.32 the steam pistons = = ... 1996.0 308.8 308.8 309.8 340.1 340.2 366.6 331.0 1996.5 kilogs. tons 309.8 340.1 340.2 366.6 331.0 1996.5 cwt. qr. Ib. 10,424 10 5 0 24 555 10 3 19 5.32 9,869 9 5.32 14 1 5 1,233.62 1 4 14 569.67 11 0 24 63.3 1 0 27 1,170.32 1 3 0 6 .586 1.29 Ib. per I.H.P. per hour.