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Traction motor
 
 
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A traction motor is a type of electric motor
Electric motor

An electric motor uses electrical energy to produce mechanical energy, nearly always by the interaction of magnetic fields and current-carrying conductors....
 used to power the driving wheels of a vehicle such as a railroad locomotive
Locomotive

A locomotive is a Rail transport vehicle that provides the motive power for a train. The word originates from the Latin language loco - "from a place", Ablative case of locus, "place" + Medieval Latin motivus, "causing motion", and is a shortened form of the term locomotive engine,....
, electrical multi-unit
Multiple unit

The term multiple unit or MU is used to describe a self-propelling train unit capable of coupling with other units of the same or similar type and still being controlled from one cab....
 train (such as a subway
Rapid transit

A rapid transit, subway, underground, elevated railway or metro system is an railway electrification system public transport rail transport in an urban area with high capacity and frequency, and which is grade separation from other traffic....
 or light rail vehicle
Light rail

Light rail or light rail transit is a form of urban rail transit public transportation that generally has a lower capacity and lower speed than Passenger_rail_terminology#Heavy_rail and rapid transit systems, but higher capacity and higher speed than street-running tram systems....
 train), a tram
Tram

A tram, tramcar, trolley, trolley car, or streetcar is a railroad car, of lighter weight and construction than a train, designed for the transport of passengers within, close to, or between villages, towns and/or cities, on tracks running primarily on streets....
, or an automobile
Automobile

An automobile or motor car is a wheeled motor vehicle for transportation passengers, which also carries its own car engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally f...
.

itionally, these are DC
Direct current

Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as battery , thermocouples, solar cells, and commutator-type electric machines of the dynamo type....
 series-wound 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
Alternating current

In alternating current the movement of electric charge periodically reverses direction. An electric charge would for instance move forward, then backward, then forward, then backward, over and over again....
 induction motor
Induction motor

An induction motor is a type of asynchronous AC motor where power is supplied to the rotating device by means of Electromagnetic induction. Other commonly used name is squirrel cage motor due to the fact that the rotor bars with short circuit rings resemble a squirrel cage ....
s known as asynchronous traction motors.






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Encyclopedia


A traction motor is a type of electric motor
Electric motor

An electric motor uses electrical energy to produce mechanical energy, nearly always by the interaction of magnetic fields and current-carrying conductors....
 used to power the driving wheels of a vehicle such as a railroad locomotive
Locomotive

A locomotive is a Rail transport vehicle that provides the motive power for a train. The word originates from the Latin language loco - "from a place", Ablative case of locus, "place" + Medieval Latin motivus, "causing motion", and is a shortened form of the term locomotive engine,....
, electrical multi-unit
Multiple unit

The term multiple unit or MU is used to describe a self-propelling train unit capable of coupling with other units of the same or similar type and still being controlled from one cab....
 train (such as a subway
Rapid transit

A rapid transit, subway, underground, elevated railway or metro system is an railway electrification system public transport rail transport in an urban area with high capacity and frequency, and which is grade separation from other traffic....
 or light rail vehicle
Light rail

Light rail or light rail transit is a form of urban rail transit public transportation that generally has a lower capacity and lower speed than Passenger_rail_terminology#Heavy_rail and rapid transit systems, but higher capacity and higher speed than street-running tram systems....
 train), a tram
Tram

A tram, tramcar, trolley, trolley car, or streetcar is a railroad car, of lighter weight and construction than a train, designed for the transport of passengers within, close to, or between villages, towns and/or cities, on tracks running primarily on streets....
, or an automobile
Automobile

An automobile or motor car is a wheeled motor vehicle for transportation passengers, which also carries its own car engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally f...
.

Motor types

Traditionally, these are DC
Direct current

Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as battery , thermocouples, solar cells, and commutator-type electric machines of the dynamo type....
 series-wound 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
Alternating current

In alternating current the movement of electric charge periodically reverses direction. An electric charge would for instance move forward, then backward, then forward, then backward, over and over again....
 induction motor
Induction motor

An induction motor is a type of asynchronous AC motor where power is supplied to the rotating device by means of Electromagnetic induction. Other commonly used name is squirrel cage motor due to the fact that the rotor bars with short circuit rings resemble a squirrel cage ....
s known as asynchronous traction motors. Synchronous AC motor
Synchronous motor

A synchronous electric motor is an AC motor distinguished by a Rotor spinning with coils passing magnets at the same rate as the alternating current and resulting magnetic field which drives it....
s are also occasionally used, as in the French TGV
TGV

The TGV is France's high-speed rail service. It was developed during the 1970s by GEC-Alsthom and SNCF, the French national rail transport operations, and is now operated primarily by SNCF....
.

Transmission types

Before the mid-20th century, a single large motor was often used to drive multiple driving wheel
Driving wheel

On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons . On a conventional, non-articulated locomotive, the driving wheels are all coupled together with side rods ; normally one pair is directly driven by the main rod which is connected to the end of the piston rod; power is transmitted to th...
s through connecting rod
Connecting rod

In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. The connecting rod was invented sometime between 1174 and 1200 when a Inventions in medieval Islam, Timeline of Islamic science and engineering and Artisan named al-Jazari built five machines to pump water for the kings of t...
s that were very similar to those used on steam locomotive
Steam locomotive

A steam locomotive is a locomotive powered by steam. The term usually refers to its use on railways, but can also refer to a "road locomotive" such as a traction engine or steamroller....
s. It is now standard practice to provide one traction motor driving each axle through a gear drive.

Usually, the traction motor is simply suspended between the truck (bogie
Bogie

A bogie is a wheeled wagon or trolley. In Machine terms, a bogie is a chassis or framework carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a swivel, as on a railway carriage or locomotive, or sprung as in the suspension of a caterpillar tracked vehicle....
) frame and the driven axle; this is referred to as a "nose-suspended traction motor". The problem with such an arrangement is that a portion of the motor's weight is unsprung, increasing forces on the track. Occasionally, other mounting arrangements are made. In the case of the GG1
PRR GG1

The Pennsylvania Railroad's GG1 class of electric locomotives were built between 1934 to 1943 at the PRR shops in Altoona, Pennsylvania, with a total of 139 units constructed....
, two truck-mounted motors drove each axle through a quill drive
Quill drive

A quill drive is a Mechanism that allows a drive shaft to shift its position relative to its driving shaft. It consists of a hollow driving shaft with a driven shaft inside it....
. The "Bi-Polar" electric locomotives built by General Electric
General Electric

The General Electric Company, or GE is a multinational corporation United States technology and Service s conglomerate incorporated in the State of New York....
 for the Milwaukee Road had gearless motors. The rotating shaft of the motor was also the axle for the wheels. In the case of the TGV power units, a motor mounted to the power unit’s frame drives each axle; a "tripod" drive allows a small amount of flexibility in the drive train allowing the trucks (bogies) to pivot. By mounting the relatively heavy traction motor directly to the power unit rather than to the truck (bogie
Bogie

A bogie is a wheeled wagon or trolley. In Machine terms, a bogie is a chassis or framework carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a swivel, as on a railway carriage or locomotive, or sprung as in the suspension of a caterpillar tracked vehicle....
), better dynamics are obtained allowing much-improved high-speed operation.

Traction control

Control of the power supplied to traction motors is, nowadays, made by complex electronic circuitry. An important part of this circuitry is a wheel speed sensor
Wheel speed sensor

A Wheel speed sensor or vehicle speed sensor is a type of tachometer. It is a sender device used for reading the speed of a vehicle's Revolutions per minute....
.

Rating

In diesel-electric
Diesel-electric

A number of vehicles use a diesel-electric powertrain for providing Motion . A diesel-electric powerplant includes a diesel engine connected to an electrical generator, creating electricity that powers electric motor traction motors....
 and gas turbine-electric locomotive
Gas turbine-electric locomotive

A gas turbine-electric locomotive, or GTEL, is a locomotive that uses a gas turbine to drive an electric generator or alternator. The electric current thus produced is used to power traction motors....
s the horsepower
Horsepower

Horsepower is the name of several non-International System of Units units of power . It was originally defined to allow the output of steam engines to be measured and compared with the power output of draft horses....
 rating of the traction motors is usually 81% that of the prime mover
Prime mover (locomotive)

In locomotives, the prime mover is the source of power for propulsion. The term is generally used when discussing any locomotive powered by an internal combustion engine....
. This assumes that the electrical generator
Electrical generator

In electricity generation, an electrical generator is a device that converts mechanical energy to electrical energy, generally using electromagnetic induction....
 converts 90% of the engine's output into electrical energy and the traction motors convert 90% of this electrical energy back into mechanical energy. Calculation: 90% x 90% = 81%.

Cooling

Because of the high power levels involved, traction motors are almost always cooled using forced air.

Manufacturers


See also

  • Air cooling
  • Electric vehicle battery
    Electric vehicle battery

    An electric vehicle battery is a rechargeable battery used in electric vehicles, making them battery electric vehicles .Batteries are usually the most expensive component of BEVs, although batteries from old or wrecked electric cars can be bought for battery-to-grid mini-power plants....
  • Induction
    Induction

    Most common meanings * Inductive reasoning, used in science and the scientific method* Mathematical induction, a method of proof in the field of mathematics...
  • Rare earths
  • Torque and speed of a DC motor
    Torque and speed of a DC motor

    The torque of an electric motor is independent of speed. It is rather a function of Magnetic flux and Armature current....
  • Virtual transmission

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