After a bearing has been running for a period of time, there will be obvious stress marks on the working surface. Not all marks indicate that the bearing is broken. The bearing will also leave stress marks when used under normal conditions.
The bearing runs under load, and the contact surface of its raceway is dull and black in appearance. But this does not mean that it is wear and tear, and it has nothing to do with life. The stress mark is called a force trace of the bearing. This trace varies with its operation and load conditions, and its appearance varies. Careful inspection can help us determine whether the bearing is operating under normal conditions.
Radial bearings, ball bearings, spherical surfaces, and double-row balls only bear radial force and can bear a small amount of axial load. Bearing amage is usually caused by excessive axial force.
(1) Unidirectional radial load: two cases, one is the inner ring rotation; the other is the inner ring fixed.
(2) One-way axial load: inner ring or outer ring rotates.
(3) Combination of unidirectional radial load and axial load.
(4) The radial load rotates synchronously with the inner ring, and the outer ring is fixed.
(5) The radial load rotates synchronously with the outer ring, and the inner ring is fixed.