Fig. 142 A.
Let a c b be the angle. Parallel with and two inches from b c draw d e, e being in a c produced. In the same manner fix the point g. At the width of the rail head (from 2¼ to 2½ inches) draw, parallel to a c, L 8. The point 8 is the limit to the solid steel. At double the rail width, or 4½ inches, draw, also, parallel to a c, 16. 6; 5. 6 is the limit of the flat steel, generally about half an inch in thickness. This is the least amount of steel allowable; it is best to steel the whole tongue, and all of that part of the wings acted upon by the wheels. The geometric point is generally very thin, and is omitted to a distance far enough back to make the point a third or half an inch wide, which is rounded off; e L and d k are made two and a half inches; as also f m and g n; k 10 and m 11 are made six or seven inches, and joined to d and f by a curve, abrupt at first, but afterwards more gentle. The distances, 5 a and 6 b must be such that a 9 is three and one eighth inches, (depending upon the breadth of rail base,) o m″ is from three to four inches. At the other end of the frog e h must be enough to make s t at least an inch, when e h and i g are from three to four inches; i m′ being, as at the other end, three or four inches. The steel plates N N are one half inch in thickness. The surface, N, is two inches above the bottom, M. The lower plate, M, is two inches thick. A B, C D, and E F are six or seven inches wide, and one inch thick. The spike holes 11
16 square, the spike being one half inch. The sharp edges, i g, e h, a c, b c, should be rounded off to fit the wheel at A, fig. 142 A. The surface of the tongue N 9 should be formed to a double incline to fit the wheel cone.
Note.—Fig. 142 A gives the shape and dimensions of the largest tires.
Another method of making a frog is to cut and weld the rails a and b of the track, as in fig. 143. The continuations of these rails are bent as shown in the figure.
Fig. 143.
The whole angle is placed upon a firm wooden bearing.
There is no weaker part of the track than the frog. To make up the strength at such places a heavy longitudinal timber twelve feet long will answer a good end.