Some switches are designed to be forced to the proper position without damage. This is sometimes known as running through the switch. In a trailing-point movement (running through the switch in the wrong direction while they are set to turn off the track), the flanges on the wheels will force the points to the proper position. This both allows for remote control and for stiffer, strong switches that would be too difficult to move by hand, yet allow for higher speeds. However, most are now operated by a remotely controlled electric motor or by pneumatic or hydraulic actuation, called a point machine. Historically, this would require a lever to be moved by a human operator, and some switches are still controlled this way. Only one of the points may be connected to the facing track at any time the two points are mechanically locked together to ensure that this is always the case.Ī mechanism is provided to move the points from one position to the other ( change the points). If the right point is connected, the right wheel's flange will be guided along the rail of that point, and the train will continue along the straight track. In the illustration, if the left point is connected, the left wheel will be guided along the rail of that point, and the train will diverge to the right. When the wheels reach the switch, the wheels are guided along the route determined by which of the two points is connected to the track facing the switch. Only in extreme cases does it rely on the flanges located on the insides of the wheels. The switch mechanism, shown in black, may be operated remotely using an electric motor or hand-operated lever or from a nearby ground frame.Ī railroad car's wheels are guided along the tracks by coning of the wheels. In this animation, the red track is the one travelled during a facing-point movement. In many cases, where a switch is supplied to leave a track, a second is supplied to allow the train to reenter the track some distance down the line this allows the track to serve as a siding, allowing a train to get off the track to allow traffic to pass (this siding can either be a dedicated short length of track, or formed from a section of a second, continuous, parallel line), and also allows trains coming from either direction to switch between lines otherwise, the only way for a train coming from the opposite direction to use a switch would be to stop, and reverse through the switch onto the other line, and then continue forwards (or stop, if it is being used as a siding).Ī straight track is not always present for example, both tracks may curve, one to the left and one to the right (such as for a wye switch), or both tracks may curve, with differing radii, while still in the same direction. Sometimes a switch merely divides one track into two at others, it serves as a connection between two or more parallel tracks, allowing a train to switch between them.
In many cases, such as rail yards, many switches can be found in a short section of track, sometimes with switches going both to the right and left (although it is better to keep these separated as much as feasible). Right-hand switches have a diverging path to the right of the straight track, when coming from the point blades, and a left-handed switch has the diverging track leaving to the opposite side. The handedness of the installation is described by the side that the diverging track leaves. Passage through a switch in this direction is known as a trailing-point movement.Ī switch generally has a straight "through" track (such as the main-line) and a diverging route. Unless the switch is locked, a train coming from either of the converging directs will pass through the points onto the narrow end, regardless of the position of the points, as the vehicle's wheels will force the points to move. it will be directed to one of the two paths, depending on the position of the points) is said to be executing a facing-point movement. A train moving from the narrow end toward the point blades (i.e. These points can be moved laterally into one of two positions to direct a train coming from the point blades toward the straight path or the diverging path. Abt switch used in 1895 built Dresden Funicular Railway (photo of 1985)Ī railroad switch ( AE), turnout, or points ( BE) is a mechanical installation enabling railway trains to be guided from one track to another, such as at a railway junction or where a spur or siding branches off.Ī switch (points) consist of a pair of linked tapering rails, known as points ( switch rails or point blades), lying between the diverging outer rails (the stock rails).
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