Traction Motors

Traction motors (TM, for short) are electric motors that vehicles with electric transmissions come equipped with. Traction motors are typically positioned around individual wheel axles, and rely on electricity to be spun and to propel vehicles.

When throttle is operated on electric vehicles, desired electrical power is sent from the power source to the traction motors. On diesel-electric vehicles, this indirectly adjusts fuel injection and engine spin rate in order to output the required electrical power from the generators.

At very low speeds traction motors receive high electric current, producing high torque. As 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 needs to be supplied to maintain the same acceleration.

When a loaded electric vehicle accelerates, it can be exposed to high current for a prolonged period. Over time, this will warm up the traction motors . Depending on the session difficulty settings , traction motors may trip the respective 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 .

At low speeds, especially when climbing positive grades under load, it is crucial to operate the throttle gently, notch by notch and keep the current at a nominal level, by carefully observing the ammeter and traction motor temperature gauges and not letting any go into red.

Electrical powertrain damage can result in individual traction motors seizing to work. Since electric vehicles usually have more than one motor, power will then be distributed to the remaining operational ones. With fewer driving axles on a vehicle, wheelslip is easier to occur, however.

Number of traction motors on a electric vehicle can be supplemented by adding a slug , in order to improve traction .

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 speed up to a certain amount, usually indicated red on the speedometer. Going above that speed can result in catastrophic failure , regardless of whether the traction motors, or the reverser , are engaged or not.

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

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