Pre-tensioning vehicle

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Biasing locomotive of the series 35 and motive power of the 01 series with a steam special on the inclined plane
ÖBB 1110 leader locomotive in front of a 1044 in Sankt Valentin station

A pre-tensioning motor vehicle or a pre-tensioning locomotive is an additional serviced motor vehicle at the head of a train .

definition

One speaks of pre-tensioning motor vehicle, leader or pre-tensioning service in railway operations when at least two working motor vehicles occupied by locomotive drivers run at the head of a train and no multiple control is available or used. A machine can also be placed in front of a double or multiple unit.

commitment

Illumination of the vehicles of a train with a leader locomotive in Switzerland
Illumination of vehicles with multiple traction

Preamble is used when different series with or without compatible multiple control are used. In the absence of multiple controls, steam locomotives usually use pre-tensioning locomotives when the tractive effort of a locomotive is no longer sufficient. The foremost traction vehicle is considered to be leading the train, the engine driver of which observes the route, emits whistling signals and operates the train brake. In the past, prestressing services were often performed. Leading locomotives were kept in reserve, especially on sections with inclines. Like real multiple traction, preload avoids pulling and compression in the train, as opposed to being pushed forward, but the load capacity of the couplings sets limits, especially in the Western European network.

Four-stream TEE multiple unit of the SBB with an Ae 6/6 as a leader

The reasons for using a pre-tensioning vehicle are:

  • Increasing the pulling force
  • Avoidance of empty runs of locomotives. In some cases, the additional locomotive is only allowed to develop enough pulling power to carry itself. If it is not possible or useful to provide a machine to be transferred as a leader locomotive, it can also be set as the final locomotive at the end of the train.
  • Increase in the braking force available on the train ( braking hundredths ).
  • Protection locomotive in front of the control car when there is a risk of avalanches . On the Gotthard mountain route , it is customary to harness a leader locomotive in front of light vehicles at the Zugspitze to prevent derailment when snow slides onto the tracks. The four-stream TEE multiple units each ran with a leader. In the snowy winter of 1999, the Cisalpino-Pendolini received an Ae 6/6 or a Re 4/4 II as a protection locomotive.

Procedure

Opening credits can be scheduled or unscheduled. Unscheduled preamble is necessary when a train is heavier than usual so that the locomotive alone is not able to move it as planned or when one locomotive is not sufficient due to special operating situations. Scheduled leader takes place when the train is regularly so heavy that a locomotive is unable to move it on schedule.

See also

literature

Web links

Remarks

  1. ↑ So it was possible for a train driver to request a leader locomotive while driving. For the Prussian State Railways , the procedure is described as follows: The train driver threw a 5 × 10 cm large, appropriately labeled wooden plaque to the local staff at an occupied station that was being driven through, and the local staff preceded the request for the moving train. At the next station that had a locomotive available, the train could be stopped and the locomotive pre-tensioned (Announcement No. 447, p. 376. In: Eisenbahndirektion Mainz (ed.): Collection of the published Official Gazettes 7 (1903). Mainz 1904. Official Gazette of August 1, 1903. No. 40).

Individual evidence

  1. ↑ Swiss Driving Regulations (FDV) A2016 Federal Office of Transport (FOT), July 1, 2016 (PDF; 3 MB). R 300.5, section  1.3.4  pre-tensioning service
  2. ↑ Snow chaos in the Alps . In: Swiss Railway Review . No. 4 . Minirex, 1999, ISSN  1022-7113 , pp. 125-135 .