Intermediate locomotive

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Union Pacific Railroad heavy freight train with four locomotives in the lead and six intermediate locomotives traveling over the Soldier Summit in Utah.

Intermediate locomotives , formerly also medium locomotives , are single or multiple working locomotives that are lined up between the wagons of a train. Intermediate locomotives are operated manually or remotely controlled by the train-carrying locomotive via radio . An intermediate locomotive must be arranged in such a way that no impact forces have to be transmitted. The use of intermediate locomotives is called intermediate service .

Intermediate locomotives are used in particular on freight trains when the trailer load exceeds the permitted drawbar load . In doing so, they take over part of the pulling force to move the mass of the wagon and prevent the train from separating . Intermediate locomotives are to be distinguished from:

  • Sliding locomotives may be transmitted impact forces and attached to the other car
  • non-working locomotives that are placed on the train as wagons in addition to the locomotive for transfer.

Adding and detaching an intermediate locomotive requires extensive track systems and more time than coupling and uncoupling a sliding locomotive . Advantages over push-pull locomotives are the higher tractive forces and the avoidance of strains and compression in the train.

Intermediate locomotives pull part of the trailer load so that the permitted drawbar load is not exceeded.

In Switzerland, intermediate locomotives were used on the Gotthard and Lötschberg mountain routes and occasionally on the Rhaetian Railway . When BLS and SBB introduced the pushing service on the two Alpine railways at the beginning of the 1990s , the intermediate service was only necessary for freight trains with a trailer load of 1,600 to 2,000 tons . Although the use of intermediate locomotives is still permitted, hardly any more of them are used.

In the English-speaking world, remote-controlled intermediate and push locomotives are known as Distributed Power Units . In addition to the additional traction force, they allow the main line pressure to be reduced at the same time , so that the compressed air brakes act simultaneously at several points on the train.
→ Main article: Distributed Power Unit

A second part of the train with the actual locomotive was placed in front of the train, which was formed with a view to the permitted draw hook load and pulled by the two intermediate locomotives.

Commuters in Vienna's local transport

A Purkersdorf commuter in 2007, recreated for historical reasons , pulled or pushed by a machine of the 1062 series

As the successor to the Viennese Stadtbahn or the forerunner of the Vienna S-Bahn , so-called commuters , officially known as short trains , used to run around the Austrian capital . These were special push- pull trains in which a smaller steam, diesel or electric locomotive was wrapped between two pushed two-axle platform wagons at the front and another two pulled two-axle platform wagons at the rear . Both the first and the last car were equipped with track clearers and headlights. The route was monitored from the locomotive in the middle, but the driver also stood at the door to the foremost platform, where he had to operate the emergency brake if necessary . The maximum permissible speed was only 40 km / h.

A classic example of this mode of operation was the so-called Purkersdorfer commuter on the Westbahn , which commuted between Hütteldorf-Hacking and Unter Purkersdorf from 1931 to 1972 . Other areas of application for such sets were the so-called bath trains on the Franz-Josefs-Bahn between Vienna Franz-Josefs-Bahnhof and St. Andrä-Wördert - there also with steam powered rail cars of the DT1 series - as well as the Südbahn .

S-Bahn Munich

In the Munich S-Bahn drove during the 1972 Summer Olympics at the special line S25 between the Munich East train station and the Munich Olympic Stadium station four trains, each consisting of twelve to fourteen n-car passed. Because only a maximum of ten cars were permitted in push-pull train operation, these sets had a control car at both ends, with the class 140 locomotive in the middle.

literature

  • Swiss Driving Regulations (FDV) A2016 Federal Office of Transport (FOT), July 1, 2016 (PDF; 3 MB). R 300.5, Section  1.3  Aligning the locomotives
  • Paul Winter: Our locomotives . Orell Füssli Verlag, Zurich 1963, p. 47 .
  • Heinrich Fäh: Pushing service on the Gotthard route. In: Swiss Railway Review. No. 5. Minirex, 1992, ISSN 1022-7113, pp. 212-213.

Web links

Individual evidence

  1. ^ Alfred Moser: The steam operation of the Swiss railways 1847-1966. Birkhäuser, Basel 1967, p. 383
  2. ↑ Swiss Driving Regulations (FDV) A2016 Federal Office of Transport (FOT), July 1, 2016
  3. ↑ Locotrol® Distributed Power System. General Electric , accessed April 1, 2017 .
  4. ↑ Local history museum - commuters. On: purkersdorf-online.at. Retrieved October 9, 2017.