To achieve satisfactory operation, double row cylindrical 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, and the friction in the lubricant, can have a detrimental effect on the rolling conditions in the bearing arrangement and may cause damaging sliding movements to occur between the rollers and the raceways.
The requisite minimum load to be applied to double row cylindrical roller bearings can be estimated using
|Frm||=||minimum radial load [kN]|
|kr||=||minimum load factor (→ product table)|
|n||=||operating speed [r/min]|
|nr||=||speed rating [r/min] (→ product table)
|dm||=||bearing mean diameter [mm]
= 0,5 (d + D)
When starting up at low temperatures or when the lubricant is highly viscous, even heavier loads may be required. The weights of the components supported by the bearing, together with the external forces, often exceed the requisite minimum load. If this is not the case, the double row cylindrical roller bearing must be subjected to an additional radial load.
Bearings to tolerance class SP specifications, when mounted, are under preload, so that it is normally not necessary to perform the above calculation.