Bearing damage caused by overheating is as follows: Severe discoloration of bearing components*). The raceway/rolling element plastic deformation is serious. The temperature changes sharply. Bearing sticks several times, see Figure 77. The hardness is lower than 58HRC. Reason: Failure of bearings due to overheating is usually no longer detected. Possible causes: The working clearance of the bearing is too small, especially insufficient bearing lubrication at high speed Excessive radial preload lubricant due to external heat sources Impeded operation due to cage fracture Remedy: Increase the bearing clearance if there is an external Heat source, to ensure slow heating and cooling, that is, to make the entire set of bearings evenly heated to avoid lubricant accumulation and improve lubrication. Evaluation of running characteristics and damage on the removed bearing Rolling Contact Mode 77: Deep adhesive indentations on the raceways of an overheated cylindrical roller bearing. *) Explanation of discoloration: When the bearing takes on a tempered color, it is related to overheating. The appearance of brown and blue is related to the temperature and duration of overheating. This phenomenon is very similar to the coloration of the lubricating oil due to its high temperature (see chapter 3.3.1.1). Therefore, it is not possible to judge whether the operating temperature is too high only from the discoloration. It can be judged from the discoloration area whether it is caused by tempering or grease: the latter usually only occurs in the load-bearing areas of the rolling elements and rings, and the former usually covers a large area of u200bu200bthe bearing surface. However, the only identification measure for the presence of high temperature running bearings is hardness testing.