Railway switch
railway switches are track constructions, which make the transition of a track to another for rail-mounted vehicles possible without Fahrtunterbrechung.
Table of contents
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fundamental ideas
technical is “switch” the generic term for most different designs. Simple switches and crossing switches are most frequent.
Switch field one calls a group of switches, which connect several parallel tracks.
components of a switch
 simple one switch with following crossing |
a switchwith hand placing weight and Weichenlaterne |
| on the left of the heart, with intermediate and Flügelschienen, on the right of a Radlenker |
interior elbow switch |
| double switch |
| a double crossing switch with tongues on the inside |
one by means of Gleisverschlingung shifted switch of a streetcar (actual switch is farther back on height of the railway catenary mast) |
| mobile heart |
 three-rail switch - unification of a normal and a oneNarrow-keep in track-strain with Jindřichův Hradec in Tschechien |
| switches in three-rail track |
 rack railway switch (Wengernalpbahn) |
 Gleiswender (Pilatus course) |
a switch is compound from special rails. The switch can be changed over by movement of the Weichenzungen. The Zwischenschienen lead from the Weichenzungen to the heart, where them beside the heart point as Flügelschienenend. One calls the rails, against which the Weichenzungen rest, stock rails. For the guidance of the wheels in the heart Radlenker are needed.
The mobile part of the Weichenzungen rests upon sliding chair plates, also ribbed slabs mentioned. Because of high maintenance costs become within the range of the German course AG todayincreases maintenance-poor tongue roll devices of different design inserted.
Switches lie on special switch ties. These are longer than normal thresholds and can consist of wood, steel or steel (stretching) concrete. With the today's new buildings in the area of the railways AG concrete sleeper switches are inserted with priority. A concrete sleeper switch draws throughtheir substantially higher dead weight with a higher Lagestabilität opposite the others out.
At the point of the switch the placing device (Weichenantrieb or hand placing device with switches localposed) is attached, with which the Weichenzungen are moved and held in the end position. The Weichenzungen become by the point catchfixed. With long switches is here an additional central catch and possibly. a fork catch necessarily. With the placing device often a Weichensignal is connected that the situation of the switch makes from a distance recognizable. If switches localposed must become secured against unintentional changing over, these are by a switch lock,Hand catch or Weichenriegel secured. If a switch is equipped with a mechanical Weichenantrieb, also here a Weichenriegel is necessary depending upon placing distance.
A red-white peg, delimiter mentioned, shows up both on the master and on the Zweiggleis the place, in that, conditions on both tracksVehicles, these would affect.
Beyond that also a switch heating can be installed. This is in the tongue range and within the range of mobile hearts, and is to prevent a Zusammenfrieren of the mobile parts (tongue and stock rail).
All switches inserted today are prefabricated in the switch work, on which building site transportsand there on a free surface from the many individual parts to majorities pre-mounts. In such a way provided switch majorities (tongue range, central range and heart range) are then lifted, aligned and welded with a crane into the track. In some cases the switch majorities become already complete in the switch work (along orprefabricated without additional equipments such as drives, linkages,), pre-mounted switch heaters etc. and can be inserted immediately. Transport is made by the road or the track. The installation takes place via a crane or a special switch transport and installed equipment.
simple one switches
in a simple switch branchesa Zweiggleis from a main track . If the main track is straight, one speaks of a straight switch, otherwise of an elbow switch. If the main track is curved into the same direction as the Zweiggleis, it concerns an interior elbow switch. The main track the Zweiggleis is oppositebent, one calls the switch external elbow switch or Y-switch. There are several Zweiggleise to a side of the main track, which penetrate each other, then one speaks of a double switch. This space-saving type of switch finds use however rarely. The symmetrical variant with the name three-way switch is still many rarerand today in the range of the railway probably any longer one does not build. With streetcars it is however still usual.
With the German course AG the switches are standardized and become as straight switches with the branch track radii 190m (40 km/h), 300 (50), 500 (60),760 (80), 1200 (100) and 2500m (140 km/h) as well as symmetrical external elbow switch with 215m (40 km/h) manufactured. In that clammy one is indicated the permissible in each case maximum speed on the branching strand. Interior elbow switches and other external elbow switches are made not than rule switches, but produced by bending of these.
crossing switches
a simple crossing switch is a crossing, which was supplemented in such a way by switches that at least in a driving direction the transition of a track is possible on the other one, also half Englishman mentioned. A double crossing switch makes transitions possible to both directions. These switcheswith new buildings due to the higher wear in exceptional cases for example with restrained conditions are only inserted. With both types between the crossing switches with tongues on the inside (usually occurring design, also Englishman mentioned) and those with external tongues (system Baeseler, very rarely) differentiated. Thoseexternal tongues make possible larger turning radii and thus higher speeds, are however more aufwändiger.
special designs
Rückfallweiche
Rückfallweichen are used frequently at single-railed distances, z. B. in the course guidance enterprise. These switches are fixed on a driving direction, however provided with a lever weight;they can be changed over like a switch localposed. When driving on the heart the rail-mounted vehicle presses the Rückfallweiche with its flanges into the other situation. Afterwards it is reset assistance of a return spring - usually after a deceleration time - automatically into the basic position. In stations alsoat least two Rückfallweichen are possible for course crossings without manual switch operation.
switch with mobile heart
with the conventional switches is briefly not led the wheel at the heart or only very little laterally. The side guidance is manufactured by Radlenker, which can lead to strong impacts.If on a distance of vehicles with differently broad flanges to be used (e.g. Streetcar vehicles on railroad lines), this solution can not be used. With switches for high-speed traffic the problem places itself that switches, which will drive on branching with high speeds (high-speed landing gear oaks), due to the flatCrossing angle very long hearts and concomitantly long heart gaps possess. In both cases switches with mobile hearts are used, which are clearly more expensive however because of/the additional drive (e) in procurement and maintenance.
For the heart mechanism there are two different types:
- mobile heart point, like oneWeichenzunge to the respective (being certain) Flügelschiene is moved (see picture)
- mobile Flügelschienen, those against (being certain) the heart point to be bent
sand switch
a sand switch has Weichenzungen similarly a simple switch, the branching strand ends however already before the heart. Becomes a sand switch in more branchingPosition traveled, leads this to a derailing. In addition, sand switches work thus similarly as track barriers and serve as this as flank protection device, may into tracks driven on of courses be built.
Schleppweiche
with the Schleppweiche does not give it passing external rails. The Weichenzungen are straightand at the Weichenspitze mobile stored, the placing device is because of the internal end of the Weichenzunge and shifts the tracks on the straight or the branching strand. The first railway switches were Schleppweichen. Since they were not reliable in service at higher speeds in particular, they became on the railways soonby other designs replaces. With Feldbahnen there are this very day individual copies.
tongueless switch
of tongue lots switches at the beginning and at the end of a three or a four-rail track are used. Whether the switch in the straight or in the branching strand will drive on, hangs of the track widthoff. Tongue lots switches have a heart, Flügelschienen and on the side of the broader trace a Radlenker. In case of a four-rail track a further heart is needed. With early horse route courses also switches without tongue were used, whereby by the course direction of the horse the driving direction was determined.
switch in the multi-rail track
in the process of three or four-rail tracks switches present are special constructions with mostly several hearts. The number of the necessary hearts depends on the kind of the multi-rail track. Also the layer (side) of the narrower trace within a three-rail track works itself in this connectionout. Further there are differences concerning the kind of the branching track. Here it can concern either around one of the two track widths or also a multi-rail track.
rack railway switch
switches, which lie in a track section with rack, require a special design. To thatPlaces, in which the rack crosses the rail, are necessary mobile pieces of rack, which are changed over with the Weichenzungen.
Gleiswender
with rack railways with a rack system punch are more conventional because of the horizontally lying gear wheels crossings between rail and rack and thus the useSwitches not possibly. Here Gleiswender are used. These consist of a framework, at which on the top side a track for the straight strand is attached and on the lower surface a track for the branching strand. The framework is swivelling around 180°, so that in both situationsRails and rack are constant. Originally instead of switches sliding stages with rack railways punches were inserted system, on which straight lines and branching strand next to each other were attached and which will likewise continuous drive on could.
strassenbahnweichen
strassenbahnweichen, which are on a distance section with own track body, differentiateonly by the substantially closer radii in branch-end yourself track of the switches usual on railways. With distance sections, which lie in the road subgrade level, there - under the special requirements - are special designs, those on railways does not occur.
simple one switch
the Spurführungtaken place with a switch, which lies in the road subgrade level, by the groove rail. Therefore no Radlenker and Flügelschienen are necessary with switches in the road subgrade level. Since with streetcars the bearing surface of the wheels is usually narrower than with Vollbahnen, this supplies in particular within the range of the heartsstronger impacts, since the bearing surface of the Rades is smaller. With switches therefore the groove rail is designed frequently as flat groove, with which the flange in the groove rolls.
With the early horse route courses tongueless switches were usual, when pointed driving on became over the course direction of the horse bottom plate thoseDriving direction on the switch determines. With the use of streetcar motor coaches tongues became necessary the controlling of the driving direction, whereby frequently switches were equipped with only one tongue.
switches know
or confine preferred Zungenvorrichtung special with streetcars also within the range of traveled roads curveslie. In order to minimize the susceptibility to interference, this frequently by means of short Gleisverschlingungen by such some meters are away continued to put to an unfavorable place. This design is also admits under the term preferred Zungenvorrichtung.
pre-sorting switch
with a pre-sorting switch is so far extended the Gleisverschlingung thatit for example over the complete length of a stop is enough, and several courses into it to bring in can. This makes possible to bring it in the streetcars slowly into the stop, whereby the switch position can be controlled exactly. Driving out from the stop can take place now faster, there also withclose sequences by several courses no more switch to be placed must.
Kletterweiche
a Kletterweiche is provisionally usually put because of construction work on the existing track, in order to be able to reroute courses on another track. The Kletterweiche exists out for this firmly connectedSchienenprofilen. Over flattened ends the courses can be driven and rerouted into the auxiliary switch.
switches with special tasks
of Schutzweiche
as Schutzweichen one generally designates switches, whose only task is it to prevent by its diverting position that a course travelby other course or ranking travels one endangers. The diverting strand of the switch leads usually into a short stump track, which is locked by a buffer-stop. In stations one e.g. finds Schutzweichen. as conclusion of crossing or overhauling tracks, and with spur tracks, if this a downward gradient to the Streckengleisexhibits.
In the frontier stations of the GDR Schutzweichen were built, in order to prevent that an engine driver flees including vehicles and passengers from the GDR.
catching switch
task of a catching switch is it to prevent a running away of vehicles into a downgrade. The switch lies inBasic position on the diverting strand, which, similarly as with the Schutzweiche, leads usually into a short stump track with buffer-stop, but contrary to this in the drive of the course lies and before driving on is changed over only briefly. One finds catching switches both in the driving out way of the mountain-lateraland behind the Einfahrsignal of the valley-lateral station.
a switch is localposed to placing devices in the simplest case. At the point of the switch is a placing support, at which the switch with muscle power is changed over. This consists of the Weichenhebel and the Stellgewicht,that the switch in the respective end position holds. Usually the placing support is connected with a Weichensignal. In the early period of the railway there were switches only localposed, which were placed by switch attendants.
For the acceleration of ranking procedures today also electrical switches localposed are used.
Switches remoteposed becomeposed from a signal tower. The oldest signal tower design is the mechanical signal tower. The Weichenantrieb is connected by a drawing wire line with the setting lever in the signal tower. The distance between switch and signal tower is limited, so that in larger stations a multiplicity of mechanical signal towers for the completion of the enterprisewere necessary.
In the 20's the 20. Century with compressed air did not intersperse itself established pneumatic Weichenantrieben in relation to the today common electrical or electrohydraulical drives with an electric motor at the point of the switch and conversion by means of electrical signals. First this drive form became inelectromechanical signal towers uses. Today whole railroad lines or underground systems will have one of the motor coach driver yielding price increase
signal towers from remote controlled
[to work on] control with streetcars streetcars usually. Normally the switch is switched thereby by means of a remote control appropriate in the flight compartment, in emergency orduring ranking travels the switches can be changed over by hand by means of a steel-pipe carried in the streetcar.
To center of the 1990er frequently the control was controlled by means of overhead line contacts for the current collectors, whereby over the power input of the streetcar the switch position could be affected. According to whether thoseStreetcar with river or without river drove rolled, could the position of the switch be changed (as exact, differed between the individual enterprises). This led however frequently to incorrect switch positions, because for example the heating in the winter, the air conditioning system in the summer, or also the driving current back supply when braking the control wrongly to affect could. Also this can be problematic, if a streetcar before a switch came to a halt, like this at stops or before secured sections (z. B. ) Seems to road crossings, since a starting streetcar can drive only heavily “without river”, overto switch the switch. Here then the use of pre-sorting switches was necessary.
Since 1996 may not depend the yielding price increase in Germany because of the fault liability therefore no more on the power input of the car. Modern controls work with inductive reporting transmission, radio or infrared price increase.
driving on ways
A switch will either
- pointedly (start on the Weichenspitze too with for the possibility of deciding for on the left of or right) or
- blunt (opposite direction, without such option)
drive on.
With double-railed distances with advantages driving direction (right traffic in Germany) also track change ranges of leading up places lead an appropriate nomenclature. With itconfusing designation “track change” contains only the possibility, not the necessity for the same.
pointedly traveled track change (two Linksweichen)
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stumpfのbefahrener Gleiswechsel (zwei Rechtsweichen)
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In most streetcar nets only blunt driven on track change was built, because with these the danger of a derailing smalleris, and above all, so that no danger of an unintentional flank travel exists. To a such flank travel it can come, if z. B. the Weichenzunge due to foreign bodies not correctly fits and at least an axle the wrong drive takes. This procedure is called “cutting open”. It is the contrast to the “rear-end collision”, which happens from the heart.
In order to make in the case of a building site during the repair or renewal of a streetcar distance a constant rail traffic possible without pointed turn travel, the intact track is driven on in both directions. Before the building site a Kletterweiche is presented, so thatthe streetcar from the closed track on the opposite side to drive can; after the building site the regularly inserted, now pointedly, is used driven on track changes in order to arrive the right side.
move GW Kletterweiche <------------- building site -----------/<
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