Minimum Load-Thrust Ball Bearings
In order to keep bearings working in a good condition, a minimum load must be imposed on bearings, particularly on bearings working at high speeds, high accelerations, or with the load direction changing frequently, because under these working conditions, inertial force of balls and cage and lubricant friction will have bad influence on the rotation of bearings, and detrimental sliding movement may be caused.
The minimum load of a thrust ball bearing can be obtained from
A M inimum load constant, see bearing dimension tables
N speed, r/min
When bearings are started at low ambient temperatures or in the condition where the viscosity of lubricant is very high, a larger minimum load is required. Usually, the weight of the bearing supporting parts plus the load on the bearing have been over the minimum load. If the weight cannot be up to the minimum load, then extra radial load must be exerted on this type of bearing in order to meet the requirement of minimum load. The requirement can be met through preloading in axial with springs.