Traction motor
1081613
225878699
2008-07-15T20:47:05Z
Attilios
428795
/* Transmission types */ That regarded only US
A '''traction motor''' is a type of [[electric motor]] used to power the driving wheels of a vehicle such as a railroad [[locomotive]], electrical [[Multiple unit|multi-unit]] train (such as a [[Rapid transit|subway]] or [[Light rail|light rail vehicle]] train), a [[tram]], or an [[automobile]].
==Motor types==
Traditionally, these are [[Direct current|DC]] 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 [[Alternating current|AC]] [[induction motor]]s known as asynchronous traction motors. [[synchronous motor| Synchronous AC motor]]s are also occasionally used, as in the French [[TGV]].
==Transmission types==
Before the mid-20th century, a single large motor was often used to drive multiple [[driving wheel]]s through [[connecting rod]]s that were very similar to those used on [[steam locomotive]]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]]) 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 [[PRR GG1|GG1]], two truck-mounted motors drove each axle through a [[quill drive]]. The "Bi-Polar" electric locomotives built by [[General Electric]] 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]]), better dynamics are obtained allowing much-improved high-speed operation.
==Rating==
In [[diesel-electric]] and [[gas turbine-electric locomotive]]s the [[horsepower]] rating of the traction motors is usually 81% that of the [[prime mover (locomotive)|prime mover]]. This assumes that the [[electrical generator]] 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.
==See also==
* [[Torque and speed of a DC motor]]
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{{Electric motor}}
== External links ==
* [http://www.associatedrewinds.com/english/deconstructingmotor.html "Deconstructing a traction motor - Associated Rewinds (Ireland) Limited"]
* [http://www.nycsubway.org/perl/show?7591 Image of a nose mounted traction motor on an [[R46 (New York City Subway car)|R46]] New York City Subway car. The motor can be clearly seen behind the axle with the gear box with the writing on it in the center.]
* [http://www.nycsubway.org/perl/show?5029 Another nose mounted traction motor on a wrecked [[R38 (New York City Subway car)|R38]] Subway car.]
* [http://www.nycsubway.org/cars/yards_coney_truck.html Coney Island Truck Repair shop; many pictures regarding traction motors]
* [http://www.nycsubway.org/perl/show?6149 Detached truck with Traction Motors.]
=== Manufacturers ===
* [http://www.acpropulsion.com/technology/gen2.htm AC Propulsion] makers of AC traction drive systems
* [http://www.adcmotors.com/ Advanced DC] makers of DC traction motors
* [http://www.automation.siemens.com/mc/mc-sol/en/03a8aecf-0d29-49c6-b52d-92309b23f4fc/index.aspx Siemens drive technology] makers of AC traction drive systems
[[Category:Battery electric vehicle components]]
[[Category:Electric motors]]
[[Category:Locomotive parts]]
[[de:Fahrmotor]]
[[ru:Тяговый электродвигатель]]
[[zh:牽引電動機]]