. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . 0° curve onthe main track the errors are not large. It has been found to bea needless refinement to compute the precise mathematicalproperties of the switch-rails from a curved main track, any-more than as given by the two principles stated above: There-fore (a) the length of the lead is assumed to be the same as that fora straight track, using the same frog, and (6) the degree of curve of the switch-rails is found a
. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . 0° curve onthe main track the errors are not large. It has been found to bea needless refinement to compute the precise mathematicalproperties of the switch-rails from a curved main track, any-more than as given by the two principles stated above: There-fore (a) the length of the lead is assumed to be the same as that fora straight track, using the same frog, and (6) the degree of curve of the switch-rails is found as statedabove—in principle (6). As the curvature of the main tracksharpens, the curvature of the switch-rails becomes less untilthey become straight. For still sharper main track, the centerof curvature is on the same side. This is illustrated in Fig. 145,if we consider the sharper curved track to be the main trackand the easier curve the switch. The above rule is still appli-cable, the algebraic sign of the result showing the location of thecenter. 307. Design for a turnout from the INNER side of a curvedtrack. As in the previous section, Fig. 145 illustrates^ the dia-. FiG. 145, gram for circular lead rails. It may be shown that the degreeof the turnout {d) is nearly the sum of the degree of the main §308. SWITCHES AND CROSSINGS. 349 track (D) and the degree (d) of a turnout from a straight trackwhen the frog angle is the same. The discrepancy in this case issomewhat greater than in the other, especially when the curva-ture of the main track is sharp. If the frog angle is also large,the curvature of the turnout is excessively sharp. If the frogangle is very small, the liability to derailment is great. Turn-outs to the inside of a curved track should therefore be avoided,unless the curvature of the main track is small. j 308. Connecting curve from a straight track. The con-necting curve is the track lying between the frog and the side ^j ^-¥ \ \ N N \ f 1 f7 11 — Q —
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Keywords: ., bookauthorwebbwalt, bookcentury1900, bookdecade1920, bookyear1922
