. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools . Fig. 135.—Stub Switch. the connecting bar (C) fastened to the switch-stand. One greatobjection to the switch is that, in its usual form, when operatedas a trailing switch, a derailment is inevitable if the switch ismisplaced. The very least damage resulting from such a derail-ment must include the bending or breaking of the tie-rods of theswitch-rail. Several devices have been invented to obviate thisobjection, some of which succeed very well mechanically, al-though their added
. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools . Fig. 135.—Stub Switch. the connecting bar (C) fastened to the switch-stand. One greatobjection to the switch is that, in its usual form, when operatedas a trailing switch, a derailment is inevitable if the switch ismisplaced. The very least damage resulting from such a derail-ment must include the bending or breaking of the tie-rods of theswitch-rail. Several devices have been invented to obviate thisobjection, some of which succeed very well mechanically, al-though their added cost precludes any economy in the total costof the switch. Another objection to the switch is the loosenessof construction which makes the switches objectionable at highspeeds. The gap of the rails at the head-block is always con-siderable, and is sometimes as much as two inches. A driving-. FiG. 136.—Point Switch. wheel with a load of 20000 to 30000 pounds, jumping this gapwith any considerable velocity, will do immense damage to the §300. SWITCHES AND CROSSINGS. 339 farther rail end, besides producing such a stress in the construc-tion that a breakage is rendered quite Hkely, and such a breakagemight have very serious consequences. 300. Point switches. The essential principle of a point switchis illustrated in Fig. 136. As is shown, one main rail and alsoone of the switch-rails is unbroken and immovable. The othermain rail (from A to F) and the corresponding portion of theother lead rail are substantially the same as in a stub portion of the main rail (AB) and an equal length of the oppo-site lead rail (usually to 22 feet long) are fastened togetherby tie-rods. The end at A is jointed as usual and the other endis pointed, both sides being trimmed down so that the featheredge at B includes the web of the rail. In order to retain in it as much strength as
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