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EZMG (pronounced EZMG) is a Soviet type of interlocking that has been imported into the GDR by the Deutsche Reichsbahn from the Soviet Union since 1976 . It controls the Soviet pre- and main signal combinations with the HI signal terms . The Russian abbreviation stands for " E lektritscheskaja z entralisazija m alych stanzij G ermanii" ( transcription ; Russian Электрическая централизация малых станций Германии) , translated as "Electrical centralization of Germany"). A total of 77 EZMG signal boxes are said to have gone into operation by 1991.

At the end of 2011 only 14 of them were still in operation, in 2019 there were still 5: Großschönau, Niedercunnersdorf, Pretzsch, Thalheim / Erzgebirge and Nebra. All others were either replaced by other signal boxes, the stations abandoned or the routes closed.



Typical for EZMG signals are the oval signal screens with the elongated barriers against solar radiation. The shunting route signal Ra 12 with two white lights rising to the right is a German specialty that does not otherwise exist in the OSJD light signal system. Most other railway administrations use a white light for this, which could be confused with the German identification light. In order to be able to display the signal aspect Ra 12, the exit signals were equipped with a cantilever between the two signal screens, which carries the second white lantern.

It is also possible to use German light signals of type WSSB , also as a dwarf signal. The adjustment of the operating voltages takes place in a transformer box on the mast. Substitute red is not provided in the interlocking logic, so that the corresponding signal lanterns are not installed in the WSSB signal screens at the bottom right. Light strips are not to be switched on, therefore only the speed levels 40 km / h and route speed can be signaled. Substitute signals on the exit signals were not provided in the original design. The corresponding circuit change was carried out by the Deutsche Reichsbahn.

Signal aspects

The main and distant signals of EZMG interlockings show terms of the Hl signal system , with the original signal screens of the manufacturer the lanterns are arranged in a row one above the other. With a fully equipped main signal, the upper signal screen has a common cast housing for three, the lower one for two light points. Light points that are not required are blindly closed; partial signal screens that are not required can be omitted. Light strips for signaling 60 or 100 km / h are not planned, so there is no green flashing light. Freestanding shunting signals (Ra 11a and Ra 12) can be used both in tall form and as a dwarf signal . The signal transformers were located in the cast iron base of the signal mast. If signals of German design are used, they are housed in a special transformer box, in the case of a tall design on the mast, in the case of dwarf signals on a special concrete post near the signal. Dwarf main signals are also possible. There is no substitute red term, with German main signal screens with assignment according to the rules, the position at the bottom right is always blind.

In addition to the signal terms shown, St. 7, ride at 40 Expect km / h to be shown.

The use of punctiform train control of the German three-frequency resonance design was not originally intended. Therefore, the relay boxes for the track magnet control relays also had to be attached to additional concrete posts behind the respective signal location.

Signal box


In contrast to other relay interlockings of comparable size, the operating and signaling systems are separated from each other on the control table . As a rule, not the position of the individual turnouts is illuminated on the message board, but only the set route for each station head. Accordingly, there is also no single changeover of points as normal operation. A route is always set at each of the two station heads, but not fixed. By setting a different route, it is still possible to switch points individually and on a trial basis. Only in special cases is there a position indicator for individual turnouts at the lower edge of the message board and the option to switch these separately.

Relay system

The relay system is based on N relays (Non-Controlled), but like C relays (Controlled) they have a monitoring function.


The EZMG signal boxes are approved for smaller stations on branch lines. For technical reasons, there are some restrictions in the design of the station. The stations must be on single-track lines and can have up to five station tracks with a maximum of 4 points per station head.

These restrictions can be circumvented to a certain extent by making adjustments:

  • Additional sidings can be connected by key-dependent manual switches.
  • Instead of a switch, two switches or a switch and a track barrier can be coupled, which are treated like one element for the logic and thus also for the operator, but rotate one after the other.
  • Instead of a continuous track, a stub track is also possible or even two stub tracks, if these are connected to the two opposite station heads.

In this way, up to 9 tracks (continuous line track, 4 butt tracks at one station head and 4 more at the other station head) and up to 16 switches are possible.

Extensive changes also allow it

  • to set up a parallel shunting route for each station head parallel to the main line or
  • another outgoing single-track line

to be integrated into the signal box. Special solutions are then created.

Switch locks and drives

Point machine with internal lock. The thick rods move the tongues, the thinner ones are the tester rods
Point drive with clamp point lock, only one control rod and lifting translator.

The point machines are integrated into the interlocking logic with two wires. Accordingly, the point machines are not compatible with the four-wire turnout circuits commonly used in Germany . This means that these drives cannot be used on German interlocking designs, and neither can German drives on EZMG interlockings. The control voltage is 160 V =, the monitoring voltage 24 V ~. Some of the point machines have drive-on clutches. Their holding force, however, is so great that the switch tongues are bent when the switch is opened. Accordingly, the drives are declared as »not openable«. Initially, the points were only secured with the internal locking of the point machines. For this purpose, special connection plates are screwed to the holes in the switch blades. Each tongue is moved by its own control rod and its position is checked by a tester rod. If such a switch has to be tied off in the event of a fault, both tongues must be secured individually. In addition, every widening of the track immediately causes the tongue to gap. There were several reasons for using the (clip) lace closures known in Germany. In this case, drives with only one control rod are used, which were originally used for track closures. Because of the difference in the travel range, the drive offers only 160 mm, while the locking mechanism of the clamp-tip locks requires approx. 220 mm, a stroke translator is installed that only extends the movement of the control rod. The tester bars are not translated because the actual travel of the switch blades does not change.

Route block

The RPB-T type track block was also imported from the Soviet Union. This transmits significantly more information with only two wires than the line block designs common in Germany with significantly more cable wires. The license change takes place by getting the license from the neighboring train registration office . The operating status of the section block is displayed in the message section of the control and signaling desk. For this purpose there are two arrows pointing away from each other and in the middle of them a message field with the inscription "Route free". If an exit is set, the "Route free" field becomes dark and the arrow in the direction of the neighboring train registration office changes its illumination from white to red. At the opposite point of the route block, the arrow pointing to this operating point also changes from white to red. Only after the train has left the starting point does the "route free" indicator go out at the destination. The train is thus completely pre-blocked, which means that the destination operating point is informed that the train has left the opposite station. The back block is triggered by an automatic train end message. For this purpose, an electromagnetic wagon inductor was hooked into the tow hook at the end of the train, which was recognized by a track control point. The actual inductor disk of the wagon inductor was about 40 cm above the top of the rail. This presupposed that there were always enough wagon inductors at the end of the route. In the case of railcars, they were carried in the vehicle when they were not in use; for freight trains, they were stored in the stations along the route. This technology was used on the Gotha – Leinefelde railway line, among other places . If the track control point is not triggered, the "Check train end" indicator lights up in the signaling desk. In this case, block back manually after the final train test. This technique was later abandoned and the route block was adapted accordingly. The wagon inductors and the track control points could thus be omitted. The block design was then called RBP-To (o for without). The "Check train end" indicator now always lights up when a train arrives. The back block must therefore be submitted manually. Due to the lack of terminal interlockings in stations with EZMG interlockings, it was not possible to check the end of a train by looking at both station heads. Axle number reporting systems (AMA) or remote monitoring systems were used in order not to generate any additional personnel costs . The driving service regulations of the DR even made it possible to waive the final train test for passenger trains under certain conditions. The semi-automatic block design RPB-To was used, for example, between Erdmannsdorf-Augustusburg and Annaberg-Buchholz lower station. On this route, which previously had no route block, existing cables were also used, in particular by crossing safety systems.

It is also possible to adapt German section block designs such as field block form C and single-field relay block. Use was made of both options.

See also


  • Hans-Jürgen Arnold et al .: Railway safety technology. 3rd, edited edition. Transpress, Berlin 1980.
  • Signals from the German railways. With all the new features of the current DB signal book. GeraMond, Munich 2007, ISBN 978-3-7654-7068-4 .
  • Carsten Weber, Ulrich Maschek: Das EZMG-Stellwerk, 2006, Chair for Traffic Safety Technology at TU Dresden, DVD

Web links

Individual evidence

  1. sachsen-stellwerke.de: "Track diagram signal box type EZMG" , as of November 24, 2011