An engineering drag losses model for rolling bearings

Rolling bearing friction is an important measure of bearing performance. With increasing industrial trends of energy savings and CO 2 footprint reduction, rolling bearing friction has become a very important parameter in the machinery design and selection process. Particular importance have high-speed applications like spindles or electrical vehicle traction drives and gearboxes. Since handling thermal effects has become an important problem to solve in these applications, oil lubrication is gaining interest due to its cooling capacity. Bearing friction is made of rolling, sliding and drag losses components in oil lubricated bearings. In this paper the emphasis is given to the drag losses component, which becomes the most critical in oil bath in medium and high-speed applications. An engineering model is derived for the calculation of this component for medium and potentially high speeds. The results are compared with experimental measurements (in-house and literature). In general, good agreement is found between the engineering model and the experimental results.