Trajectory phenomenon of misalignment of failed bearings: For FAG ball bearings, the load trajectory of the stationary ring is not vertical, but inclined in the axial direction, see Figures 38 and 39. For roller bearings, the track on one side of the raceway is clearer than on the other side in the inclined state, see Figure 40. Reason: Shaft flexure split bearing housing or vertical bearing housing misalignment The two surfaces of the adjacent structure are not perpendicular. There is dirt between the adjacent surface and the bearing ring during installation. The bearing clearance that is subjected to moment and load at the same time is too large . Remedy: Refer to installation instructions for permissible inclination, see FAG catalogue to ensure cleanliness during installation. 26 Pair of removed bearings to evaluate running characteristics and damage. Rolling contact mode 38: Misalignment Bearing a: Wrong housing When centered, the inclination of the inner ring relative to the outer ring b: The relative deflection of the two inner rings when the shaft is deflected c: The trajectory of the deep groove ball bearing with the inner ring rotating during misalignment d: The FAG deep groove when the outer ring rotates during misalignment Trajectories of ball bearings 3.3.2 Indentation failures on raceway and rolling element surfaces Indentations often appear in the rolling contact area of u200bu200bbearing components, and the occurrence of dents may arise from a variety of reasons. If these indentations are numerous and evenly distributed, then when analyzing the trajectory (section 3.3.1) it is necessary to consider whether they are caused by the cyclic movement of foreign particles in the bearing. The following is mainly related to ferrules. Evaluation of running characteristics and damage on the removed bearings Rolling contact mode 39: Inclined trajectory on the inner ring raceway of a deep groove ball bearing 40: Inclined trajectory on the inner ring raceway of a FAG tapered roller bearing 3.3.2.1 Fractured bearing during cyclic motion , the material of the raceways and rolling elements is subject to constant alternating stress. So the failure mode approximates the fatigue of the mating part under bending stress: the propagation of fatigue fracture. In rolling bearings these fracture areas develop largely parallel to the raceway surface and eventually lead to surface spalling, also known as: fatigue failure, surface spalling, cratering, pitting, microscopic cratering, etc.