After the mounting has been completed, a running test should be conducted to determine if the bearing has been mounted correctly. Small machines may be manually operated to assure that they rotate smoothly. Items to be checked include unfavorable running caused by foreign matter, visible flaws, indentation, and overlarge rotation torque caused by improper mounting or an improper mounting surface. If there are no abnormalities, load-up operation may be started.

Large machines which cannot be turned by hand shall conduct inertial rotation upon immediate stop of power after no-load rotation, and then we can confirm if there is abnormal vibration before going to power operation.

Powered operation starts from low speed and no load, and then gradually increase the speed, load, etc. to their normal levels. Items to be checked during the test operation include the existence of abnormal noise, excessive rise of bearing temperature, leakage and contamination of lubricants, etc. If any abnormality is found during the test operation, it must be stopped immediately and the machine should be inspected. If necessary, the bearing should be dismounted for examination.

Although the bearing temperature can generally be estimated by the temperature of the outside surface of the housing, it is more desirable to directly measure the temperature of outer ring using oil holes for access.

The bearing temperature should rise gradually to the steady state level within one to two hours after the operation starts. If the bearing or its mounting is improper, the bearing temperature may increase rapidly and become abnormally high. The cause of this abnormal temperature may be an excessive amount of lubricant, insufficient bearing clearance, incorrect mounting, or excessive friction of the seals.

The sound of a bearing may be checked with a noise locator or other instrument. Abnormal conditions are indicated by a loud metallic sound ,or other irregular noise, and the possible cause may include incorrect lubrication, poor alignment of the shaft and housing, or the entry of foreign mater into the bearing.