International Correspondence Schools · Scranton, Pa. : The Colliery engineer co. · leaf 515
is 15inches, and the width b of the mouth is 7 inches, then thefrog number is 88 -=- (15 -f 7) = 4. Frogs are known bytheir numbers. That in Fig. 523 is a No. 4 frog. 1680. The Frog Angle.—The frog angle is the angle formed by the gauge lines of the rails, which form itstongue. Thus, in Fig. 523,… … to the middle point b of the heel c d., we form a right-angledtriangle, right-angled at b. The perpendicular line a b. TRACK WORK. 1105 bisects the angle c7, and, by rule 5, Art. 754, we have tan a =: ifa b The dimensions of the frog point given in Fig. 524 are not the same as those given in Fig.…
Railroad engineering
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