. Railway age gazette . roximate horsepower a locomotive is developing forthe known draw bar pulls and speeds on a dynamometer test. Let HP = horsepower, F := tractive effort or draw bar pullin pounds, and V = speed in miles per hour. Then HP = FV-i- 375. A series of horsepower lines on ordinary rectangularcross section paper would be a series of hyperbolas, as this To make chart it is only necessary with logarithmic paperto plot two points for each of the equations Z = J^Y^ andU = YiW Thus, draw a straight line through the points .2, .02and .4. .08 for the first and one through the poin
. Railway age gazette . roximate horsepower a locomotive is developing forthe known draw bar pulls and speeds on a dynamometer test. Let HP = horsepower, F := tractive effort or draw bar pullin pounds, and V = speed in miles per hour. Then HP = FV-i- 375. A series of horsepower lines on ordinary rectangularcross section paper would be a series of hyperbolas, as this To make chart it is only necessary with logarithmic paperto plot two points for each of the equations Z = J^Y^ andU = YiW Thus, draw a straight line through the points .2, .02and .4. .08 for the first and one through the points .3, .009 and6, .072 for the second. This chart could be used as it stands,or it could be used to prepare a nomogram similar to that onpage 381 of the .August 29, 1913, issue of the Railway Age a chart to represent these equations were made on ordinarycross section paper, a series of points would have to be found 1000 Ibi. Drayv-Bar Pull or TracHfe EfforA i 7 8 9 ZO 4C SO SO 70 80 90 100,000 FbrZ^Y^ .OE . . .OS .06 .07 .08 .09 .1 Square .006 .007 . Cubic Inches . . .4 .S .6 .7 .a .9 .OS .oe .07 .08 .09 ./ I Chart Illustrating the LIses of Logarithmic Paper equation is of the form xy = c, x ^ F, y = V, and c = would be a laborious task to construct a large number ofthese; also they would not be very accurate unless a considerablenumber of points were plotted for each. On logarithmic paper,on the contrary, these horsepower lines are all straight andparallel to each other, makmg angles of 45 deg. with the makes it necessary to find only one point for each line tomake the chart as shown. for each of the equations and curves drawn through these points,as shown. Mr. Pomeroys tractive effort chart, in the RaiKvay AgeGazette, Mechanical Edition, August, 1913, page 436, is a com-bination of graphical division and multiplication, for which pur-pose logarithmic paper is ideal. Another advantag
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroa, bookyear1913
