Compounding and Superheating in Horwich Locomotives
M.\RCH 1910. 399 COMPOUNDING AND SUPERHEATING IN HORWICH LOCOMOTIVES. BY MR. GEORGE HUGHES, Member. CHIEFMECTI~NICAL EXGINEER, LANCASHIRE AND YORESHIRERAILWAY, HORWICH. When using the diagrams, tables, and illustrations given in this Paper it should be remembered that the Lancashire and Yorkshire Rail way is made up of severe gradients, numerous junctions, many goods depots and sidings, and that it runs through a very thickly populated district, consequently, with densc traffic, it is extremely difficult to operate. COMPOUNDING. For many years the compounding of locomotives has been a siibjcct of controversy, and to-day opinions are divided. Even a very important element, the ratios of volume of the high and loa-pressure cplinders, is debatable, for we find them as low a5 1 to 1.69, and as high as 1 to 3, and even more. It appears to the autlior, when comparing the area of a simple engine cylinder with that of the low pressure of a compound, if the back-pressure on the low-pressure piston iR not proportionatdy lower than in the Downloaded from pme.sagepub.com at UNIV NEBRASKA LIBRARIES on June 4, 2016 400 ('OXPOGNDING ATZD SUPERHEATING. ~IAI:CHl!ll(J. simple engine, it is better not to over-cylinder a compound on the low-pressure side. The question of boiler pressures is another point upon which much diversity of opinion exists, as pressures varying from 140 to 230 lb. per square inch are in use, or have been tried. On tbis point, the author considers that steam-pressure should not be raised simply for compounding, because per se this produces greater efficiency at the cost of increased boiler maintenance.
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