Bearings - an indispensable part of almost all, without exception, the rotating parts of different mechanisms. From tiny to almost gigantic proportions, from high-speed to low-speed but the most accurate, they perform one main task - to provide a rotation or twist one part relative to another. But no matter how safe was not bearing, whatever favorable conditions it did not work there is always the probability of a sudden its failure, not to mention those that operate in harsh environments with periodic or permanent overloads. And after the sudden failure or another problem may arise in the determination or selection of necessary bearing.