Imágenes de páginas





1. Let the heavy parallels in the figure represent the rails of the main track.





2. Stick a pin or drive a spike at A, the toe of switch, at a distance from the gauge side of the main-track rail equal to the throw of the switch-rail. Lay off the distances AC and A B (if a double turnout), taken from the foregoing tables, and place the frogs C and B, or mark those points. Stretch the cord from A to B, and from B to C. Mark the middle points of those stretches at H and P. Catch the cord at H with your forefinger, and pull it outwards until your finger, at E, lines with the switch-rail, and also with the right gauge side of frog B. Stick a pin at L, half-way between H and E. Let the cord spring in against L, so that it shall stretch straight from A to L, and from L to B. Opposite the middle points, V, of those stretches, stick pins on the outside at a distance from the cord equal to one-quarter of HL. In like manner, catch the cord at P, the point midway between B and C; stretch it to F, in line with the gauge sides of the frogs; and stick a pi

3. Next lay off the proposed line of the near rail of the side track, X D. Mark the point G on that line where the range of the proper gauge side of frog C strikes it. Measure C G. Set off G D, equal to CG, along the side-track line, and drive a pin at D. Stretch the cord from C to D. Mark the middle point of it at K, and drive a pin at N, half-way between K and G. Stretch the cord from C to N, and from N to D. Stick pins outside the middle points, M and O, of those stretches at a distance from those points, M and O, equal to one-quarter of KN.

4. These three sets of pins will fix the line of one rail of the turnout. The corresponding rail of a double turnout can be laid off from them, if required, by symmetrical measurements.

5. In the case of a singie turnout, stretch the cord from the toe of switch, as above, to the point of frog, located by the foregoing tables ; catch it at the middle, and pull it outwards to a point in range with the line of the switch-rail in one direction, and the gauge side of frog in the other direction. Half-way between that point and the middle of the cord, when straight, stick a pin. Measure that half-way distance, and divide it by 4; call the quotient the “ quarter-distance.” Stretch the cord from the pin just set to the toe of switch in one direction, and to the point of frog in the other. Outside the middle points of these short stretches, lay off the “quarterdistance," as above found, and stick two other pins. These three pins will sufficiently mark the line of the outer rail of the turnout. 6. The same methods will apply in practice to turnouts from

In the latter case, the distance C G is to be calculated as follows:

Multiply the distance Y D, between the nearest rails of the parallel tracks, by the number of the frog, taken from the foregoing table. Thus, on the full gauge, with a space between tracks of 7 feet and a No. 6 frog, the distance CG would be 7 X 6= 42 feet. Lay off CG, in range of the gauge side of the frog, and stick a pin at G. Measure out GD, equal to CG, and set another pin at D, making D Y the proper distance between tracks. Then stretch the cord from D to C, and pro





1. Having located frogs B and C by the preceding methods, stretch the cord any convenient distance, C D, in the range of

[merged small][ocr errors][merged small][merged small][merged small][merged small]

the outer gauge side of the frog C. Set off EF parallel to CD, and distant the gauge-width from it. The intersection of said parallel at F with the near rail of the side track marks the spot for point of side-track frog; the curve F G, thence to toe of switch, corresponds to AC on the main track, and may be staked out in like manner.



1. Having located frogs B and C by the preceding methods, set off the width of gauge, CD, from point of frog C, and square to its outer gauge side. Stick a pin at D.

2. Next calculate the distance D E to the point of side-track

tance, HI, between the gauge sides of the nearest rails of tho main and side tracks; multiply the remainder by the number


of the frog, taken from foregoing tables. The product will be

« AnteriorContinuar »