Traction motor

Traction motor refers to an electric motor providing the primary rotational torque of a machine, usually for conversion into linear motion (traction).

Traction motors are used in electrically powered rail vehicles such as electric multiple units and electric locomotives, other electric vehicles such as electric milk floats, elevators and conveyors as well as vehicles with electrical transmission systems such as diesel-electric, electric hybrid vehicles and battery electric vehicles. Additionally, electric motors in other products (such as the main motor in a washing machine) are described as traction motors.

Transportation applications

Railroad

Traditionally, these were series-wound brushed DC motors, usually running on approximately 600 volts. The availability of high-powered semiconductors (such as thyristors and the IGBT) has now made practical the use of much simpler, higher-reliability AC induction motors known as asynchronous traction motors. Synchronous AC motor are also occasionally used, as in the French TGV.

Before the mid-20th century, a single large motor was often used to drive multiple driving wheels through connecting rod that were very similar to those used on steam locomotives. Examples are the Pennsylvania Railroad DD1, FF1 and L5 and the various Swiss Crocodiles. It is now standard practice to provide one traction motor driving each axle through a gear drive.

Usually, the traction motor is three-point suspended between the bogie frame and the driven...
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