. American engineer and railroad journal . , and it will, perhaps, surprisesome to know that under certain conditions the increase isvery great. In order to determine what this variation would amount toin actual practice, calculationswere made on a locomotive ofthe consolidation type, with 20by 24-inch cylinders, 150 pressure, drivers,and having a total weight ofengine and tender of 105 heating surface was 1,774square feet, and the grate area31 square feet. The maximumcut-oif permitted by the valvegear was 90 per cent, of thestroke, and as the most eco-nomical cut-
. American engineer and railroad journal . , and it will, perhaps, surprisesome to know that under certain conditions the increase isvery great. In order to determine what this variation would amount toin actual practice, calculationswere made on a locomotive ofthe consolidation type, with 20by 24-inch cylinders, 150 pressure, drivers,and having a total weight ofengine and tender of 105 heating surface was 1,774square feet, and the grate area31 square feet. The maximumcut-oif permitted by the valvegear was 90 per cent, of thestroke, and as the most eco-nomical cut-off for a single ex-pansion engine is at 25 or 30per cent., deductions were maueat 30, 60 and 90 per cent, cut-offs, at speeds of 5 and 10 milesper hour. As the boiler was notlarge enough to supply steam atthe 90 per cent, cut-off at ahigher speed than 10 miles perhour, the computations for 15miles an hour were made for30, 45 and 60 per cent, each of the three speedswe have, therefore, determinedthe consumption of fuel at the. point of greatest fuel economy, the point of greatest powerwhich the engine can exert at the given speed, and at a pointintermediate between the two. The coal consumption for eachpoint was calculated from the cylinder volume at point of cut-off, the cut-off pressure, mean effective pressure and weight ofsteam, allowing 25 per cent, for cylinder condensation at 30 percent, cut-off, and 10 per cent, at 90 per cent, cut-off. The rateof combustion and corresponding rate of evaporation were alsofigured, and also the tractive power of the engine and the loadwhich it would haul (back of tender) on a level, on a one percent, grade and on a two per cent, grade. From these datathe pounds of coal per 100-ton-miles were readily following table explains the method followed, giving thevalues at 10 miles per hour: Data figured at Cylinder volume Cut-off pressure Mean effective pressure Mean available pressure ...Weight per cu. ft.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
