Minimum load

To achieve satisfactory operation, spherical roller bearings, like all ball and roller bearings, must always be subjected to a given minimum load, particularly if they are to operate at high speeds or are subjected to high accelerations or rapid changes in the direction of load. Under such conditions the inertia forces of the rollers and cage(s), and the friction in the lubricant, can have a detrimental influence on the rolling conditions in the bearing arrangement and may cause damaging sliding movements to occur between the rollers and raceways.
The requisite minimum load to be applied to spherical roller bearings can be estimated using



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where

Pm=equivalent minimum load [kN]
C0=basic static load rating [kN] (see product data)
In some applications it is not possible to reach or exceed the requisite minimum load. However, if the bearing is oil lubricated lower minimum loads are permissible. These loads can be calculated when n/nr ≤ 0,3 from



Start calculation

and when 0,3 < n/nr ≤ 2 from



Start calculation

where

Pm=equivalent minimum load [kN]
C0=basic static load rating [kN] (see product data)
n=rotational speed [r/min]
nr=reference speed [r/min] (see product data)
When starting up at low temperatures or when the lubricant is highly viscous, even greater minimum loads than Pm = 0,01 C0 may be required. The weight of the components supported by the bearing, together with external forces, generally exceeds the requisite minimum load. If this is not the case, the spherical roller bearing must be subjected to an additional radial load.
NoWear spherical roller bearings have proven to give reliable operation at very low loads. They can with stand longer periods of insufficient lubrication, sudden variations in load and rapid speed changes.