TURNOUTS AND SWITCHES.
Thrnortts.—On single-traek railways, on which trains mnst be run in both directions, it is necessary to provide some means whereby one train may turn from the main track to permit another to pass by. Again, it is necessary to provide means whereby one train may be able to pass another p,-oing in the same direction, and in the ease of a double track it will often be regnired to transfer a train from one set of tracks to the other. To meet these requirements, turnouts are provided at various points along the line of the road, their number being regulated by circumstances and by locality. To connect the turnout with the main track, or, in the case of the double track, to connect the two tracks with each other, various devices have been invented, of which, however, the one most commonly used is the switch. From both tracks branch-tracks are laid, curving in opposite directions and connected by a straight piece of track, the entire arrangement being called a tnrnout. The forward part of the device, from the point where the tracks to be united separate into branches at an acute angle to the crossing of the niain rail by the outer one of the turnout,. is designated specially as the switch, while the rail-section at the point where the rails diverge is called the frog,(p. 24, jigs. 33, 34).
Cross-szeitchcs.—Turnouts lying in opposite directions between two tracks to be connected and symmetrically disposed between the two are termed cross-switches (fi/. 2S, fig. 3). Where one track intersects another, we have a crossing. On Plate 24 (fig. 31) is shown a crossing at a very acute angle, in which the transfer of trains from either of the main tracks to the other may be accomplished. In this arrangement, besides the sim ple frogs at the ends of the switch, two double frogs are provided at the central part.
Stub-szeitch.—A simple form of switch in general use is the so-called "stnb-switch," in which the switch-rail (that is, the movable section of rail inserted between the inain and the side track) has blunt or square ends, which can be thrown, by means of a switch-lever, in line with one or the other set of tracks. This arrangement is seen on Plate 25 (fig-. 7). It is
evident that in the event of the displacement of a switch of this kind the train will be derailed.
Point-si-eitch.—In the split-, tongue-, or point-switch the switch-rail is pointed. The operation of this type of switch will best be understood from the diagram (fig. 6), in which the flanges of the rails are omitted for the sake of clearness. The upper part of the fignre exhibits the switch set for the main line; the lower part shows it set for the turnout. The outer two rails of the combination—the so-called " stock-rails "—are continuous, and are spiked to the ties throughout. By means of fish-plates the heels of the two pointed switch-rails are usually fastened to the ends of the rails which lead to the frog. The pointed ends of the switch-rails are left free, to be moved about their heels or fulcrums. The pointed or free ends of the switch-rails are connected with each other by means of connecting bars, and are thrown so as to make communication with either the main line or the turnout by means of the switch-lever (jig. 13). The pointed end or " toe" of each switch-rail permits it to fit close up to the head of the main-track rail, with which it may be in contact. On this account the name " point-switch " is commonly applied to this type of switch. That the weight of the passing; train may not come upon the thinnest portion, where the metal is not strong enongh to bear it, the top of the switch-rail, from the point some distance back, is made somewhat lower, so that the pointed portion shall lie under the head of the main rail. As a. precaution to prevent the possibility of a wheel-flange striking a point, short sections of rail—called " guard-rails "—are laid down opposite the parts, close to and parallel with the main rails.