. Field-book for railroad engineers. Containing formulas for laying out curves, determining frog angles, levelling, calculating earth-work, etc., etc., together with tables of radii, ordinates deflections, long chords, magnetic variation, logarithms, logarithmic and natural sines, tangents, etc., etc . 78 ProblenB. Having run a curve A B (Jig. 29) of radius li , terminating in a tangent B D, to Jind the radius IV ordeflection angle D of a curve A C, that shall terminate in a given paralleltangent Fig. 29. A K iSolution. Since the radii Z? F and CG are perpendicular to the par-allel tangen
. Field-book for railroad engineers. Containing formulas for laying out curves, determining frog angles, levelling, calculating earth-work, etc., etc., together with tables of radii, ordinates deflections, long chords, magnetic variation, logarithms, logarithmic and natural sines, tangents, etc., etc . 78 ProblenB. Having run a curve A B (Jig. 29) of radius li , terminating in a tangent B D, to Jind the radius IV ordeflection angle D of a curve A C, that shall terminate in a given paralleltangent Fig. 29. A K iSolution. Since the radii Z? F and CG are perpendicular to the par-allel tangents CE and B L>, they are parallel, and the angle A GG =Therefore, A C G, the half-supplement of A G C, is equal t«4 m CIRCULAR CURVES. A B F, the half-supplement of A F B. Hence A B and B C are in thesame straight line, and the new tangent point C is the intersection olA B produced with C E. Represent AB by c, and A C = c -\- B C by c. Measure B C, or, ifmore convenient, measure D C and find B C by calculation. To calculate D C B C from D C, we have B C =^ ^-^^ j^^^ (Tab. X. 9), and the angle DBC = ABK= BAK, the total deflection from .4 to B. Then the triangles AFBandAG C give A B : AC = BF: C G,oy c : c = R:R; ,.R = 50 50 Sub- To find Z), we have (§ 10) /vl = ^^^, , and R = ^^^ -sdtuting these values in the equation for R, we have gj^ jy, = 50 TX 50sin. D . sin. D = -, sin. D. 79. Problem. Given the length of tico equal chords A C and B C[Jig. 30), and the perpendicular CD, to
Size: 1668px × 1498px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, booksubjectrailroadengineering
