Electrical currents, generated by asymmetries in a motor’s magnetic circuit, can lead to the premature failure of traction bearings like the ones found in axle boxes. As well as potentially harming bearing elements, lubrication can become contaminated, burn away, or behave unusually under the influence of a passing current.If a suitably insulated solution is not deployed, craters can form on the bearing material itself as fragments of the bearing material break away. Similarly, electric pitting is a common sign of more powerful electrical current damage. As rolling elements pass over these craters or pits, a secondary failure mode, fluting, occurs leaving grey stripe-like patterns along the raceways.

While the continued optimization of rail infrastructure, mainly in motors and overhead power lines helps to alleviate these electrical issues, they are almost impossible to eradicate completely. The most appropriate fortification strategy is to introduce bearings that are comfortable dealing with modern AC technology.

Hybrid Bearings: Best of Both Worlds
Implementing hybrid bearings that combine a steel surface with ceramic rolling elements is one method for extending maintenance intervals and lowering risk of application failure. Having been the preferred choice for high-speed machine tool applications for decades, their light weight and ability to perform under demanding lubrication conditions means they are a solid solution for electric vehicle powertrains too.