A diesel electric locomotive is the most common type of locomotive, or train engine, currently in use on railroads around the world. In this type of locomotive, a diesel engine provides power to an electric generator. The electricity generated then provides the power to engines connected to the locomotive's wheels, turning the wheels and allowing it to move.
In a diesel electric locomotive, the engine is not a drive engine turning the wheels and moving the train, as is frequently believed. The diesel engine is basically a power source. This is useful because diesel engines have several advantages. They are extremely reliable, easy to start, and are much simpler to repair than other types of engines. By having its own power source, the diesel electric locomotive is able to run on any kind of track.
The engine in the diesel electric locomotive provides power to an electric generator. In this way, the locomotive provides electricity to separate motors that move the locomotive's wheels. These are called traction motors. The traction motors are located inside the locomotive, and move the axles connected to the locomotive's wheels. This action moves the locomotive's wheels, causing the locomotive to travel down the track bringing the rest of the train along with it.
The diesel electric locomotive was first used in Sweden in the year 1913. It combined diesel engine technology created in 1892 by Dr Rudolf Diesel in Germany, with technology created in 1866 by Frank Sprague for use in electric street cars in the United States. The diesel electric locomotive was soon in use in several European countries. Use in the United States came a little later when General Electric began working on a design during World War I, but soon decided to just build the electric portions. Other companies built the bodies, and by the late 1920s, several companies were producing diesel electric locomotives for several railroad lines in the United States.
Once production began, the diesel electric locomotive was adopted rapidly by railroads. It had several advantages over earlier steam locomotives. Steam locomotives took a long time to start and frequently needed expensive maintenance and repairs. They also needed to stop often to pick up fuel, using enormous amounts of coal and water. In contrast, diesel electric locomotives were able to run much longer between stops and were far less expensive to maintain, making them a cost effective choice for modern railroads.