A locomotive (from neulat.loco motivus , moving from the spot), also called a tractor or locomotive for short , has been used since its invention to refer to both a track or rail-bound and a freely movable work machine, which after the period of exclusive use has been further developed as a versatile steam locomotive to a predominantly track-bound traction vehicle with different drive technologies.
Differentiation according to the type of drive
Usually a distinction is made between steam locomotives , locomotives with internal combustion engines and electric locomotives according to the type of drive . Other drives , for example using propellers (see rail zeppelin ) or rocket drives , only existed in individual test vehicles . Fireless steam locomotives are found in limited operating railway systems , for example in potentially explosive areas in the chemical industry. Rarely occurring dual-power locomotives are, for example, locomotives that can optionally obtain their traction power from a generator driven by a diesel engine or from overhead lines or busbars .
Steam locomotives get their primary energy from the combustion of the fuels they mostly carry with them , previously often peat or wood , then coal (all on an open grate), as well as coal dust or heavy oil . They are a further development of the steam engine . The fuel required for the drive are in cargo spaces (carbon boxes) or tanks on the locomotive or on an attached Schlepptender carried.
The steam locomotive boiler heated in this way generates the steam pressure for the cylinders from water that is also carried in water boxes on the locomotive or in the attached tender . These transmit the compressive force to the drive rods , which are connected to the drive axle via a drive crank .
The steam locomotive was the original and long prevailing type of locomotive. It has been almost completely replaced by electric and diesel locomotives in the USA since the 1960s, in Switzerland since 1960, in the Federal Republic of Germany with the Deutsche Bundesbahn since 1977 and in the GDR and in Berlin with the Deutsche Reichsbahn since 1988. In Asia, for example in the People's Republic of China , India , Thailand and North Korea , but also on some German narrow-gauge railways , steam locomotives are still in regular service.
Internal combustion engine locomotives
With internal combustion engines powered combustion engines require intermediate systems or transmission, since the internal combustion engine when stationary or at very low speeds can provide no torque. With diesel-electric drive, the diesel engine first drives a generator that generates the electricity for the electric traction motors. With a diesel-hydraulic drive, the motor movement is transmitted to a flow converter gear, the output shaft of which is connected to the axles.
Earlier and small diesel locomotives sometimes also transmit their power via manual transmissions (diesel-mechanical locomotives). Direct power transmission from slow-running engines via crank gears has not become established.
Locomotives with gasoline engines and other forms of combustion engines are only of historical importance . The gas turbine drive has not found widespread use either, despite numerous experiments and occasional use in operations.
Electric locomotives (short electric locomotives, electric locomotives or electric locomotives) have a purely electric drive in contrast to, for example, diesel-electric or electric-steam-powered locomotives. Electric locomotives usually get their primary energy while driving from overhead lines or from a lateral conductor rail via pantographs .
The discontinuous storage of electrical energy in accumulators is also common. Locomotives with electric traction motors that get their power from a generator driven by a diesel engine are commonly classified as diesel locomotives.
Modern electric locomotives only have single-axle drives . The wheel sets together with the traction motor are usually combined in paired bogies with two or three wheel sets each, which support the superstructure.
Last stage of development are three-phase drives , consisting of the alternating or direct current of the catenary or the generator with diesel-electric drives in frequency the phase current to drive the three-phase traction motors win. With this technology, multi-system locomotives can run at different overhead line voltages and frequencies.
Differentiation according to application purposes
In addition to the type of drive, earlier types of locomotives were also divided into express, passenger and freight locomotives, as well as shifter and small locomotives. However, general-purpose locomotives that can pull both fast passenger trains and freight trains are increasingly being used for line operations . In passenger trains, multiple units are increasingly replacing trains with locomotives. A distinction between new and highly standardized locomotives according to their operating mode can only be found in the respective extreme areas, i.e. at very high speeds of over 200 km / h or very high train loads. A relativizing role in these assignments is also played by the fact that the old and still operational locomotive stock is often still used for train services with lower power requirements.
Small locomotives are locomotives with a small size and relatively low drive power for light shunting tasks. Various drives are used for these, including diesel engines , gasoline engines and battery-powered electric motors . Also steam locomotives storage and compressed air locomotives and rail tractors are expected to small locomotives.
- Br (uno) Böhm-Raffay: Comparison of an electric locomotive with a steam locomotive. In: Ludwig Kusminsky (Red.): Journal for electrical engineering . Volume 19 (1901), Issues No. 35 and 36/1901, commission ), Vienna 1901 - part 1/2 (pp. 420-423) online , part 2/2 (pp. 430-434) online . Spielhagen & Schurich (
- Michael Brandhorst, Torsten Dellmann, Andreas Haigermoser, Markus Hecht, Stefan Karch, Günter Löffler, Wolfgang Rösch: Rail Vehicle Manual. Development, production, maintenance . Ed .: Christian Schindler. DVV Media Group, Hamburg 2014, ISBN 978-3-7771-0427-0 ( table of contents online [PDF; accessed on June 8, 2016]).
- Thomas Hornung (Hrsg.): The big book of the locomotives. DuMont, Cologne 2001, ISBN 3-7701-8676-1 .
- dlr.de , September 19, 2012: http://www.dlr.de/dlr: Train with battery on board (December 23, 2016)