In order to ensure satisfactory performance, needle roller/angular contact ball bearings, like all ball bearings and roller
bearings, must always withstand a certain minimum load acting on the radial and axial directions, especially if they are to be operated at high speed or Subject to rapid acceleration or rapid changes in load direction. Under these conditions, the inertial forces of the rolling elements and the cage and the friction of the lubricant may have a detrimental effect on the rolling condition of the bearing arrangement and may cause destructive sliding between the rolling bodies and the raceways.
The minimum necessary radial load applied to a radial needle bearing can be estimated using the following formula:
Frm = 0.02 C
The minimum necessary axial load for angular contact ball bearings can be calculated using the following formula:
In the middle
Frm = lowest radial load, kilonewton
Fam = lowest axial load, kilonewton
C = basic dynamic load rating (see product table), kilonewton
C0 = basic static load rating (see product table), kilonewton
Dm = average diameter of the
bearing
= 0,5 (d + D), mm
n = speed, rev / min
Higher loads are required even at low temperatures or when the viscosity of the lubricant is very high. The weight of the components supported by the bearing plus the external force generally exceeds the necessary minimum load. If this is not the case, additional radial and/or axial loads must be applied to the needle/angular contact ball bearings.
