Traction Motors

Motorized rail vehicles with electric drivetrains are propelled by traction motors. These are electric motors that are typically positioned around vehicles' axles, and rely on electricity to run.

When throttle is operated on electric vehicles, electrical power is delivered from the power source to the motors, through a series of different components. On diesel-electric vehicles the response may be a bit delayed, because the engine needs to spool up in order to generate the required power.

At very low vehicle speeds traction motors produce high torque with high electric current. As the speed increases, however, traction motors produce increasingly more counter-electromotive force. This force opposes the supply voltage, causing both current and torque to drop. The faster the vehicle goes, the more power it needs to maintain the same acceleration.

For this reason, it is crucial to add the throttle notch by notch, and always keep the current at a nominal level, by carefully observing the ammeter and traction motor temperature gauges, and not letting any go into red.

When an electric vehicle accelerates under heavy load, it can be exposed to a high current for a prolonged period. This can warm up the traction motors . Depending on the session difficulty settings , traction motors may trip their breaker when they overheat, or much worse - short-circuit and set the vehicle on fire. A very high current surge can trip the breaker even before it comes to overheating, although still at a risk of damage.

Damage to electrical powertrain can result in individual traction motors seizing to work. Since electric vehicles usually have more than one motor, power is automatically distributed to the remaining operational ones. With fewer driving axles on a vehicle, wheelslip is more likely to occur, however.

An electric vehicle's traction can be improved by adding a slug .

On some electric vehicles, traction motors can dynamically reconfigure their circuits to better optimize load on the generator. This is called “transition”, and results in brief disengagements of traction motors at certain speeds. This is normal behavior.

Traction motors can only withstand speeds up to a certain amount, usually indicated red on the speedometer. Going faster than that can result in catastrophic failure , even if traction motors are in no way engaged.

For the traction motors to be operational, respective breakers need to be enabled.

Installing an amp limiter , or overheat protection gadgets, makes it easier to manage traction motors' load and temperature.

One of the advantages of traction motors is their rheostatic and regenerative braking ability.