The choice of whether to use grease or oil should be based on the speed and operating temperature of the application. Axial-radial cylindrical roller bearings are typically lubricated by an oil bath or circulating oil system. Grease is normally reserved for lower speed and lower temperature applications.
Grease or oil can be introduced into the bearing via the lubrication holes in the bearing rings. Note that if the bearing is over-lubricated, excessive frictional heat increases bearing operating temperature.
The technical specifications of the standard grease in greased axial-radial cylindrical roller bearings (designation suffix G) are listed in table 1.
To achieve the lowest frictional moment and temperature, axial-radial cylindrical roller bearings need to be properly run-in. A typical running-in procedure consists of rotating the bearing for one hour at different speed steps, starting from an initial value of ~ 15% of the maximum operating speed and increasing by steps of 10% each time. During running-in, the bearing operating temperature should not exceed 70 °C (160 °F).