Traction motor

Information about Traction motor

A traction motor is a type of electric motor used to power the driving wheels of a vehicle such as a railroad locomotive, electrical multi-unit train (such as a subway or light rail vehicle train), a tram, or an automobile.

Traditionally, these are 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 AC induction motors known as asynchronous traction motors. Synchronous AC motors are also occasionally used, as in the French TGV.

Before large scale dieselization in the mid-20th century, a single large motor was often used to drive multiple driving wheels through connecting rods that were very similar to those used on steam locomotives. 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 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. 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.

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

See also


 •  • [ e]
Electric motors
Broad Motor CategoriesSynchronous motor • AC motor • DC Motor
Conventional Electric Motors Induction • Brushed DC • Brushless DC • Stepper • Linear • Unipolar • Reluctance
Novel Electric Motors Ball bearing • Homopolar • Piezoelectric • Ultrasonic • Electrostatic
Motor ControllersAdjustable-speed drive • Direct Torque Control • Direct on line starter • Electronic speed control • Variable-frequency drive
See alsoBarlow's Wheel • Nanomotor • Traction motor • Lynch motor • Mendocino motor • Repulsion motor • Inchworm motor • Booster (electric power) • Brush (electric)

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electric motor converts electrical energy into mechanical energy. The reverse process, that of converting mechanical energy into electrical energy, is accomplished by a generator or dynamo.
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locomotive is a railway vehicle that provides the motive power for a train. The word originates from the Latin loco - "from a place", ablative of "locus", "place" + Medieval Latin motivus, "causing motion").
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a major revision or rewrite and needs further review. You can help!

This article is about Multiple Units vehicles. For the train control technology, see Multiple-unit train control.

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rapid transit, underground, subway, elevated or metro(politan) system is a railway — usually in an urban area—with a high capacity and frequency of service and grade separation from other traffic.
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Light rail or light rail transit[1] (LRT) is a form of rail transport system that generally uses electric rail cars[2] on private rights-of-way or sometimes in streets. Light rail is a step below rapid transit, which is fully grade-separated.
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tram, tramcar, trolley, trolley car, or streetcar is a railborne vehicle, lighter than a train, designed for the transport of passengers (and/or, very occasionally, freight) within, close to, or between villages, towns and/or cities, primarily on streets.
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automobile (from Greek auto, self and Latin mobile moving, a vehicle that moves itself rather than being moved by another vehicle or animal) or motor car (usually shortened to just car) is a wheeled passenger vehicle that carries its own motor.
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Direct current (DC or "continuous current") is the constant flow of electric charge. This is typically in a conductor such as a wire, but can also be through semiconductors, insulators, or even through a vacuum as in electron or ion beams.
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thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as a switch, conducting when their gate receives a current pulse, and continue to conduct for as long as they are forward biased.
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alternating current (AC) is an electrical current whose magnitude and direction vary cyclically, as opposed to direct current, whose direction remains constant. The usual waveform of an AC power circuit is a sine wave, as this results in the most efficient transmission of
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TGV (train à grande vitesse, French for "high-speed train") is France's high-speed rail service developed by GEC-Alsthom (now Alstom) and SNCF, the French national rail operator, and operated primarily by SNCF.
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Dieselisation or Dieselization (see spelling differences) is generally used for the nowadays increasingly common use of diesel fuel in vehicles, as opposed to gasoline or steam engines.
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twentieth century of the Common Era began on January 1, 1901 and ended on December 31, 2000, according to the Gregorian calendar. Some historians consider the era from about 1914 to 1991 to be the Short Twentieth Century.
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driving wheel is a powered wheel which is driven by the locomotive's pistons (or turbine, in the case of a steam turbine locomotive). On a conventional, non-articulated locomotive, the driving wheels are all coupled together with side rods (also known as coupling rods); normally
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connecting rod or conrod connects the piston to the crank or crankshaft.

Internal combustion engines

In modern automotive internal combustion engines, the connecting rods are most usually made of steel for production engines, but can be made of aluminium (for
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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.
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bogie is a wheeled wagon or trolley. In mechanics 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 train carriage or locomotive, or sprung as in the suspension of a
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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. They remained in service with the PRR's successors until the early 1980s.
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quill drive is a mechanism that allows a drive shaft to shift its position (either axially, radially, or both) relative to its driving shaft. It consists of a hollow driving shaft (the quill) with a driven shaft inside it.
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General Electric Co.

Public (NYSE:  GE )
Founded 1878 in Menlo Park, New Jersey
Founder Thomas Alva Edison
Headquarters Fairfield, Connecticut,[1] USA

Key people Jeff Immelt, Chairman & CEO
Keith Sherin, Vice Chairman, CFO
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Chicago, Milwaukee, St. Paul and Pacific Railroad

Former Milwaukee Road system. Solid red lines are trackage still operated by CP Rail; purple lines are trackage now operated by other railroads; red dotted lines are abandoned.
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bogie is a wheeled wagon or trolley. In mechanics 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 train carriage or locomotive, or sprung as in the suspension of a
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bogie is a wheeled wagon or trolley. In mechanics 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 train carriage or locomotive, or sprung as in the suspension of a
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Torque and speed of a DC Motor

Torque of an electric motor is independent of speed. It is rather a function of flux and armature current.

N=K.(V-IR)/flux

where:
  • N=number of turns
  • K=proportional constant
  • R=resistance of armature (Ohms)

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electric motor converts electrical energy into mechanical energy. The reverse process, that of converting mechanical energy into electrical energy, is accomplished by a generator or dynamo.
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A synchronous electric motor is distinguished by its rotor spinning at the same rate as the oscillating field which drives it. Another way of saying this is that it has zero slip under usual operating conditions.
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An AC motor is an electric motor that is driven by an alternating current. An AC motor consists of two basic parts:
  • An outside stationary stator having coils supplied with AC current to produce a rotating magnetic field, and;

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A DC motor is designed to run on DC electric power.
  • The brushed DC motor will generate torque directly from DC power applied to the motor leads, due to its internal commutation.

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Adjustable speed drive (ASD) or variable-speed drive (VSD) describes equipment used to control the speed of machinery. Many industrial processes such as assembly lines must operate at different speeds for different products.
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Direct torque control is one method used in variable frequency drives to control the torque (and thus finally the speed) of three-phase AC electric motors. This involves calculating an estimate of the motor's magnetic flux and torque based on the measured voltage and current of the
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