The bearing damage caused by overheating is as follows: the bearing parts are severely discolored*). The raceway/rolling body has serious plastic deformation. The temperature changes drastically. The bearing has stuck several times, see Fig. 77. The hardness is lower than 58HRC. Reason: usually no longer detect failed bearings due to overheating. Possible reasons: The working clearance of the bearing is too small, especially the insufficient lubrication of the bearing at high speed. The radial preload caused by the external heat source is excessive. The operation is blocked due to the fracture of the cage. Remedial measures: Increase the bearing clearance if there is external The heat source should ensure slow heating and cooling, that is, make the whole set of bearings evenly heated to avoid accumulation of lubricant and improve lubrication. Evaluate the running characteristics and damage of the disassembled bearing. Rolling contact mode 77: The rollers of the overheated cylindrical roller bearing left deep adhesive impressions on the raceways. *) Description of discoloration: When the bearing shows a tempered color, it is related to overheating. The brown and blue appearance is related to the temperature and the length of overheating time. This phenomenon is very similar to the phenomenon of coloring due to high lubricating oil temperature (see section 3.3.1.1). Therefore, it is not possible to judge whether the operating temperature is too high from the discoloration alone. From the discoloration area, it can be judged whether the discoloration is caused by tempering or grease: the latter usually only appears in the load-bearing area of u200bu200brolling elements and rings, while the former usually covers a large area on the bearing surface. However, the only measure to determine whether there is a bearing running at high temperatures is hardness testing.