Safety driving circuit

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A Sifa pedal in the IC control car . To the right of the foot switch for the macro microphone .

The safety driving circuit , or Sifa for short , (not to be confused with the dead man's device ) is a device built into locomotives that brings a train to a standstill by means of emergency braking if the driver becomes incapacitated during the journey.

In particular, it complements the train control systems that work from the outside, such as punctual train control , liner train control or the European Train Control System, and enables one-man control of locomotives.

In Switzerland , the safety driving circuit is referred to as a safety control .

description

The Sifa in the driver's cab consists of one or more operating devices, which must be operated continuously and briefly released and pressed again at certain time intervals. Emergency braking takes place if it is not operated. Depending on the railway company and vehicle, different control elements are provided:

  • Pedal (most common)
  • Pushbutton on the side windows (if the driver is standing there when leaving the station)
  • Heads of travel switches and brake levers
  • Pull handle under the rotating drive switch, e.g. B. at the SNCF
  • Push buttons on the armrests
  • alternatively also actuation of individual operating elements such as driving switches or PZB / Indusi
The Sifa indicator light in ICE 3

In Germany the time-time Sifa is common. With this, the train driver holds down a pedal or a button , whereby the pressure must be briefly interrupted at least every 30 seconds. The safety driving circuit thus receives confirmation that the engine driver is still able to react. If one of the actuation elements of the driver is pressed for more than 30 seconds, the system warns the driver optically, after 2.5 seconds also acoustically and after a further 2.5 seconds the brake of the train is activated by the safety driving circuit. The braking effect is canceled as soon as the pedal has been released and pressed again; in addition, the drive switch must be moved to the zero position once. The time-dependent Sifa has the disadvantage that the release is independent of the distance covered.

With the time-distance Sifa, as it is used in most vehicles in Switzerland, for example , the time and the distance covered since the last operation are included in the process. This has the advantage of actively intervening even when slowly rolling away.

In Austria a way-way-Sifa is mostly used. As with the time-time sifa, the pedal must be pressed continuously and briefly released every 900 meters at the latest. If this does not happen, an acoustic warning is given after another 75 meters. If there is still no response, the traction vehicle automatically initiates a power cut-off or an emergency brake. In newer vehicles such as the Taurus family or the Talent , a time-time Sifa based on the German model is already installed. If, for example, a city ​​shuttle push-pull train , which normally has a path-way sifa, is hauled by a Taurus, the composition of the train includes both time-time sifa and distance-way sifa, depending on the direction of travel. Sifa, which is why train drivers need to be trained for both systems. A special position in Austria was the 1012 series , which automatically switched from distance-way-Sifa to time-time-Sifa at speeds over 160 km / h.

In Sweden , the pedal must not be fully depressed, but must be held in a central position, otherwise the Sifa will also respond. When driving with the train protection switched on, the pedal must not be released. In addition to the Sifa pedal, the MTAB locomotives have a push button on a helical telephone cord , which enables the driver to get up while driving.

In most countries, the safety control is active as soon as the vehicle drives faster than 3 km / h. In the Netherlands, this is already active at a standstill as soon as a driving direction is selected.

In electrical drive trains such as U- and S-webs was the DSD long time with the operation of the automatic driving switching mechanism connected. This is where the term dead man's button first became established. If the button was released (driver falls asleep etc.) there was an emergency brake.

The function of the Sifa must be checked at least once a day in every driver's cab , the operational readiness must also be checked continuously while driving.

With the introduction of the Railway Construction and Operating Regulations on May 8, 1967, the equipment of leading vehicles with safety driving gear was made mandatory in Section 28 (5) .

Description of selected Sifa designs in Germany

RZM-Sifa

This pre-war design was specified by the Reichsbahn-Zentral-Maschinenamt. After the Second World War , it was still used in the pre -series machines of the DB series V 200.0 .

The RZM safety driving switch must be operated continuously while driving. Periodic letting go is not required. It therefore offers no protection in the event that the driver collapsed over the actuating elements and was unable to act.

All actuating elements are electrically connected in series. The monitoring circuit must be interrupted by actuating at least one element. When the circuit is closed, a solenoid valve is fed, which begins with the venting of a delay air tank. The pressure in the delay tank keeps the main air line closed via a valve . As soon as the delay tank is vented after approx. 8-10 seconds, the safety reaction begins, as air can now escape from the main air line. The automatic braking can be canceled by interrupting the circuit to the solenoid valve and thus refilling the delay tank. The RZM-Sifa only becomes effective above 15 km / h, as a speed sensor basically keeps the monitoring circuit open up to this speed.

Time-Path Sifa type BBC

BBC type Sifa on a locomotive. The red lever is used to switch on and off

With this Sifa, a detector lights up after 30 seconds of uninterrupted actuation, after another 75 meters a buzzer sounds, after another 75 meters there is an emergency brake. This Sifa was very common in the first series of new post-war locomotives.

The path dependency of the Sifa is produced by a drive worm driven by the gear set. While the time relay expires, the worm wheel, which is attached to a lever and provided with a return spring, is lifted out of the engagement of the drive worm by an electromagnet. After the 30 seconds have elapsed, it falls onto the drive screw and is rotated. After 75 meters, a contact on the worm wheel feeds the buzzer. After another 75 meters, the toothing of the worm wheel ends, so that the lever falls on the outlet valve. The main air line is vented. The pressure drop also opens a pressure switch. In the case of electric locomotives, this causes the motor contactors to fall off. In diesel locomotives, the control air system is vented electrically so that the engine idles and the hydraulic transmission is emptied.

Sifa 86

After serious accidents caused by drivers who fell asleep and who regularly pressed the corresponding pedal even when they were asleep, a further developed Sifa design ( Sifa 86 ) was used on the Deutsche Reichsbahn in the GDR . With this so-called request Sifa, the driver has to confirm a visual signal by pressing a button after a period of time determined by the system at random between 40 and 50 seconds. Previously performed operator actions had no influence. If more than 400 meters (for vehicles with a maximum speed of less than 100 km / h) or 800 m (for vehicles with a maximum speed of 100 km / h) have been covered since the last activation, the system also prompts you for a new one, regardless of the previous time Actuation on.

Safety control in Switzerland

Excerpt from the vigilance control flow chart. After 1600 m a warning signal sounds, after another 200 m rapid braking is initiated.
The BDe 4/4 was the first SBB vehicle to be fitted with a vigilance control as standard.

The device in which the driver has to continuously press a pedal is referred to in Switzerland as a safety control . If the pedal is released, an acoustic signal sounds after 3 seconds at the latest. Unless it is actuated again, an emergency brake is triggered. With certain vehicles (e.g. SBB Re 420, SBB Re 620) the warning is given after 50 m and the emergency braking after another 50 m. This monitoring mode is also known as "high speed". The response of the safety control can be deactivated at speeds below 15 km / h in order to improve the overview when maneuvering . The safety control is mandatory for all adhesion and trams .

Large-scale introduction of electric operation in the 1920s made it possible to drive vehicles in principle without leader assistant to lead. In order to bring the train to a stop automatically if the locomotive driver is unable to work, the safety control system was introduced as early as the 1920s. Originally, the locomotives equipped with safety controls mainly carried passenger and freight trains. Express trains over longer distances and night trains continued to be operated by two men.

Vigilance control

The introduction of driver's cabs for seated operation led to the search for solutions that not only monitor the presence of the locomotive driver, but also his ability to act. After several years of testing, the safety control with vigilance control, also known as "slow speed", was introduced in 1950. The driver has to confirm his readiness for duty at certain time or distance intervals. After no more than 500 to 1600 meters or 30 to 60 seconds (depending on the vehicle) he must z. B. briefly release the pedal or operate the drive or brake control. Otherwise the main switch is automatically switched off after another 200 meters and an emergency brake is initiated. All adhesion, cogwheel and trams must be equipped with the vigilance control. In the past it was only required for vehicles with seated service.

Norms

  • The safety driving circuit is regulated by DIN VDE 0119-207-5.
  • UIC641 contains the conditions for safety driving circuits in international traffic.
  • Implementation provision of the Railway Ordinance (AB-EBV) AB 55.1 regulates the implementation of safety control in Switzerland.

References and comments

  1. ↑ a b The engine driver can, for example, faint , suffer a stroke or make an operating error due to fatigue or distraction .
  2. ↑ a b c Ernst Anderegg: Safety controls for traction vehicles .
    Schweizerische Bauzeitung, Volume 68 (1950), Issue 15 (E-Periodica, PDF 3.0 MB)
  3. ↑ a b c d e Federal Department of the Environment, Transport, Energy and Communication: Implementation Regulations for the Railway Ordinance (AB-EBV) , as of July 01, 2016
  4. ↑ loksim.de , last accessed on March 16, 2015
  5. ^ Ernst Kockelkorn: Effects of the new railway building and operating regulations (EBO) on railway operations . In: The Federal Railroad . tape 41 , no. 13/14 , 1967, ISSN  0007-5876 , pp. 445-452 .
  6. ↑ If the engine driver leaves his position, for example to watch the train on the other side while it is leaving, he can press a push button there as an alternative.
  7. ↑ a b c Bruno Lämmli: Security is a top priority , accessed on April 20, 2013
  8. ↑ Initial trials were in 1927 with 30 Ae 3/6 I made. ( Schweizerische Bauzeitung, Volume 89, 1927, Issue 15, p. 202 ).
  9. ^ A b Hans Schneeberger: The electric and diesel traction vehicles of the SBB . Volume I: years of construction 1904-1955. Minirex AG, Lucerne, 1995. ISBN 3-907014-07-3 , pp. 16-17.
  10. ↑ In the introductory phase, this meant that locomotives without safety control completed longer mileages than vehicles that had already been converted.
  11. ↑ Hans Schneeberger: The electric and diesel traction vehicles of the SBB . Volume I: years of construction 1904-1955. Minirex AG, Lucerne, 1995. pp. 92 and 102.
  12. ↑ Moving the control panel and applying the brakes are common actions of the engine driver, each time waking up. The warning horn only sounds when the vehicle has rolled 1600 meters without any manipulation.
  13. ^ Karl Meyer: The locomotives series Re 4/4 II and Re 4/4 III of the SBB .
    Schweizerische Bauzeitung, Volume 88 (1970), Issue 14 (E-Periodica, PDF 11.3 MB), p. 330
  14. ↑ Implementing provisions for the Railway Ordinance (AB-EBV) DETEC , July 1, 2016 (PDF; 3 MB). AB 55.1  Safety control and train control