ep line
A connection cable between the railway vehicles is called the ep line and is necessary for the operation of the electropneumatic brake (ep brake). This cable is usually located between the pneumatic connections of the main and feed line and, in its original form, has four poles to control the ep brake.
purpose
The system with the ep line is used specifically for train formation consisting of locomotives and passenger cars. The ep line supports the main air line by means of electrical signals when activating the compressed air brake. By simultaneously releasing and applying the brakes electrically controlled in all vehicles carried, u. a. good driving comfort can be maintained.
Standard UIC 541-5
With this standard, the cable was extended to nine poles, with the previous functions being supplemented by the message "Emergency brake pulled" to the leading vehicle and the activation of the emergency brake override (NBÜ). An emergency brake bypass valve can be activated in the vehicle in which a passenger emergency brake was operated via an electrical pulse from the vehicle in front. This blocks the (further) ventilation of the main air line and prevents an undesired stop.
A 120 Ω data line is also available. Instead of the 18-pin UIC cable, this can also be used for the train bus (WTB) or another type of ( push-pull train control ). Train end monitoring is implemented via pilot contacts or pressure switches at the end of the train. The previously four-pole plug devices are compatible with the nine-pole ep cable. However, the function of the emergency brake override and the 120 Ω data line are missing on the four-pole line.
In the case of freight wagons, the ep line can also be used to a limited extent for energy supply.
Standard UIC 541-6
This standard is based on the previous NBÜ2004 standard used in Germany . With the newer system, the wire assignment and the electrical signal parameters for the emergency brake override were changed and the so-called emergency braking requirement was introduced.
The main difference to the UIC 541-5 standard is that the NBÜ valves can now be continuously advanced, especially when driving on open roads. This prevents even a brief venting of the main air line if a passenger emergency brake is activated. This can effectively prevent unintentional braking at low speeds. The transmission of the message "emergency brake applied" to the leading vehicle has also been modified with the standard.
The systems UIC 541-5 and 541-6 are not compatible with each other with the exception of the functions of the ep brake. Even within the UIC 541-6 standard , wire assignments and voltage levels that deviate from the international specification are permissible for the pilot control of the NBÜ valves. For this reason, train compositions must always be composed of individual vehicles that are technically pure in this regard. It is possible to equip vehicles in such a way that they use both or several wiring variants.
Control of the ep brake and the NBÜ via UIC cable
There is also a further system for passenger coaches for the above-mentioned functions, which uses the lines of the 13- or 18-pin UIC cable by means of multiple use of existing lines. The system is mainly used for wagons and locomotives that do not have the ep line according to UIC 541-5 or 541-6. There are also vehicles that have both types of train control lines and can implement the functions via cable routes.
Apart from this, there are other processes that can only be used in train sets that are technically compatible with one another.
Other uses of the term »ep brake«
In railway vehicles, other electropneumatic braking methods are often referred to as ep brakes as soon as solenoid valves are involved in controlling brake pressures . Examples of this are the old railcars of the Berlin S-Bahn, whose single-release compressed air brakes were made multi-release by the electropneumatic control, as well as passenger coaches in the former USSR and its successor states. With these, there was and still is an additional electropneumatic control of the single-release air brake of the Matrossow type.
literature
- Frank Minde: Basics of Railway Brake Technology (PDF; 144 kB). Minden (Westphalia), 2007