. Railway maintenance engineering, with notes on construction . Fig. 83.—Ajax Manganese Guard Rail. is called the lead. This is determined by the switch angle andthe frog angle as shown in Fig. 84. (j = Gauge; p = Theoretical point of frog; D = Toe of frog; C = Heel of switch rail;AC = Length of switch rail;AB = Lesid; /^== Frog angle;a = Switch angle. If we extend PD and AC to intersect at 7, then DI = CI =tangent distance of lead curve. The switch angle is determined by the length of the switchrail and the heel distance. For high speed it is obviously desir-able to make this angle small and
. Railway maintenance engineering, with notes on construction . Fig. 83.—Ajax Manganese Guard Rail. is called the lead. This is determined by the switch angle andthe frog angle as shown in Fig. 84. (j = Gauge; p = Theoretical point of frog; D = Toe of frog; C = Heel of switch rail;AC = Length of switch rail;AB = Lesid; /^== Frog angle;a = Switch angle. If we extend PD and AC to intersect at 7, then DI = CI =tangent distance of lead curve. The switch angle is determined by the length of the switchrail and the heel distance. For high speed it is obviously desir-able to make this angle small and a longer point or switch rail 146 RAILWAY MAINTENANCE is used than for turnouts designed for slow speed. The heeldistance was formerly limited by the room necessary for theangle bars, but where a heel block is used this distance can bereduced somewhat, as previously A a- B Fig. 84.—Diagram of Turnout. Authorities differ as to the definition of the frog American Railway Engineering Association defines it as one-half the co-tangent of one-half the frog angle.* (Fig. 85A.) On
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1915
