. 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 . ion by logarithms this becomes (Tab. X. 29) £^= 72 + 1^ = h i9~d) (i^4- ^)sin. i(/^—^y Having thus found R + ^ g, we find R by subtracting ^ g. B F ufound, as in the preceding problem, by the formula 7^ E = fJ — d 3 sin. !(/+ 6) ■ S4 CIRCULAR CURVES. Example, Given g = , d = .42, S = 1^
. 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 . ion by logarithms this becomes (Tab. X. 29) £^= 72 + 1^ = h i9~d) (i^4- ^)sin. i(/^—^y Having thus found R + ^ g, we find R by subtracting ^ g. B F ufound, as in the preceding problem, by the formula 7^ E = fJ — d 3 sin. !(/+ 6) ■ S4 CIRCULAR CURVES. Example, Given g = , d = .42, S = 1^ 20, and F = 7^ to find «. Here i (^ —c/) = i (F-f 5) = 4^ 10 I (Z—5) = 2° 50 sin R + ^g ^ R = 52. Problem. To find mechanically the proper position of a givenfrog. Solution. Denote the length of the switch rail by /, the length of thefrog by/, and its width by w. From B as a centre with a radiusBH= 2/, describe on the ground an arc G H K {fig. 15), and fromthe inside of the rail at G measure G H = 2 d, and from H measureHK such that HK: B H = ^ ic : f ov HK: 21 ^ ^ tv : f; that is, HK = y-. Then a straight line through B and the point K will■-trike the inside of the other rail at F, the place for the point of the. tTOg. For the angle HB K has been made equal to h ^ and if B Mbe drawn parallel to the main track, the angle MBH is seen to beequal to h S. Therefore, MBK = BFC = ^ (F-[• S), and thiswas shown (§ 50) to be the true value of B F C. 53. If the turnout is to reverse, and become parallel to the maintrack, the problems on reversed curves already given will in generalbe sufficient. Thus, if the tangent points of the required curve arefixed, the common radius may be found by § 40 If the tangent pointat the switch is fixed, and the common radius given, the reversingoint and the other tangent point may be found by ^ 37, the change)f direction of the two tangents being here equal to S. Bur. w
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectrailroadengineering
