Bearings for railway applications

The most commonly used bearing types in rail vehicle gearboxes are cylindrical roller bearings, tapered roller bearings, angular contact ball bearings, four point contact ball bearings and deep groove ball bearings. In traction motors, most typical are cylindrical roller bearings and deep groove ball bearings. Often these bearing types are electrically insulated, with a corresponding coating on the outer or inner ring. For particularly demanding applications, hybrid variants are available.

The rolling elements of hybrid bearings are made from heavy duty silicon nitride (Si3N4), an extremely hard wearing ceramic. Bearings for gearboxes and traction motors can also be customised and produced to special specifications, for example higher thermal resistance or more stringent tolerance ranges.

"Our design of electrically insulated cylindrical roller bearings and deep groove ball bearings includes an oxide ceramic coating," says Klaus Grissenberger, application engineer with NKE in Steyr, Austria. "This offers simple, effective protection against bearing damage from current passing through the bearing.

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