. The Street railway journal . inutes and following horizontally to Hast-ings the average speed between these two stations is seen to be18 miles per hour. (5) The weight of every train arriving or leaving the GrandCentral Station on a given day was obtained and its averagespeed between stops determined from the above curves. Know- In Column 11 the product of pounds per ton, times totaltonnage of train. In Column 12 the average horse-power required to haul a train,exclusive of the locomotive, from Grand Central Station to 125thStreet; this value was obtained from Fig. 18 and is5227 X =
. The Street railway journal . inutes and following horizontally to Hast-ings the average speed between these two stations is seen to be18 miles per hour. (5) The weight of every train arriving or leaving the GrandCentral Station on a given day was obtained and its averagespeed between stops determined from the above curves. Know- In Column 11 the product of pounds per ton, times totaltonnage of train. In Column 12 the average horse-power required to haul a train,exclusive of the locomotive, from Grand Central Station to 125thStreet; this value was obtained from Fig. 18 and is5227 X = 458 hp. No stop being made at 138th Street, Columns 13, 14, 15 and 16are blank. In Column 17 the average speed from 125th Street to Junctionis found as above. In Column 18 average pounds per ton draw-bar pull overthis run. In Column 19 the average total draw-bar Column 20 the average horse-power required at the draw-bar over this run. The horse-power required for each scheduled train over each Sflee J in M,/eBfertfaur. il 1! ism 31 11 i FIG. 17.—SPEED IN MILES PER HOUR a 1 FIG. 18.—HORSE-POWER EXERTED AT DRAW-BAR ing, therefore, the average draw-bar pull in pounds required tohaul a train, and the average speed at which this draw-bar pullwas exerted, the horse-power at the draw-bar becomes H. P. =r foot pounds per minute/33,000. = draw-bar pull X miles per hour X 5280/33,000 X draw-bar pull X miles per hour/375. This formula is represented graphically in Fig. 18, from which,knowing the draw-bar pull and speed, the horse-power or kilo-watts corresponding thereto is determined. Thus, for example,if the draw-bar pull is 4300 lbs. at a speed of 36 miles per hour,to find the horse-power or kilowatts corresponding thereto at4300 lbs. on the ordinate at the left of the figure, follow the dottedline to the right until it intersects the required speed curve, thencedownward to the base line, thus obtaining 410 hp. If the efficiency01 the motor is taken at 70 per cent, by
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
