. Automotive industries . ffect the time consumed in covering aroute, even if low gear must be employed in overcomingthem. The grade scale stands for the usual per cent 2 shows that this scale is not strictly proportionateto the drawbar pulls required for hauling loads. The lineAC is the 20 per cent grade, but the line BC is the gradedemanding a drawbar pull twenty times stronger (apartfrom the traction resistance of the surface in both cases)than that required for a 1 per cent grade. AE is the 10per cent grade, and varies so slightly that the differencecan scarcely be illustrated,
. Automotive industries . ffect the time consumed in covering aroute, even if low gear must be employed in overcomingthem. The grade scale stands for the usual per cent 2 shows that this scale is not strictly proportionateto the drawbar pulls required for hauling loads. The lineAC is the 20 per cent grade, but the line BC is the gradedemanding a drawbar pull twenty times stronger (apartfrom the traction resistance of the surface in both cases)than that required for a 1 per cent grade. AE is the 10per cent grade, and varies so slightly that the differencecan scarcely be illustrated, from the grade over which thedistance travelled is exactly ten times the rise of the road,making the needed pull just ten times smaller than theweight hauled. The discrepancy grows progressively asthe grade gets steeper but is unimportant and not evensufficient to balance against another small discrepancyarising from the fact that the low gears required for thesteeper grades nearly always are slightly less efficient than. Fig. 1—Graph of resistances to vehicle movementsdue to grades and irregular or soft road surface.;Each square represents a total resistance deteimined by its vertical and horizontal distance fromlIn zero point at the lower left corner. Thelight area at this corner therefore represents good roads having light grades and favorable surfaces. The adjoining area in shading repre- ,./,- common roails. anil the rest of the sqitarei difficult and unusual conditions increasing inverity toward the upper, right comer. The oblique linesshine the total resistance which can hi OVelcme on each of the (our gear speeds of a loadedI, nek and hjl the sami Irucl; ichcu pulling a loaded trailer the higher gears. These matters, while worth watchingid serious errors, sink into insignificance compared to the li ness in estimates of grades, surface resistances and distribution of weight and loads which can never beavoided in practice. The scale of surface resistance in the graph, F
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectaeronautics, bookyear
