Ball and Needle Bearing Friction Correlations Under Radial Load Conditions

Experimental friction data for Conrad ball bearings and caged needle bearings rarely appear in the open literature. However, accurate bearing friction estimates are important in identifying the efficiencies of rotating equipment. Analytical friction models for these bearing types are complex, and, if available, reside with the bearing manufacturer. Needle bearings are perceived to have lower friction than ball bearings for the same shaft diameter, although no experimental data were found to substantiate this claim.

To obtain accurate bearing friction values for candidate bearings, a series of friction measurements under different radial load and lubricant conditions was made. From these tests, two new friction correlation equations were developed for radial load and oil-jet lubrication conditions of Conrad ball bearing and caged needle bearings.

These correlation equations provide a guide for the engineer interested in the effect of certain bearing parameter changes on bearing friction.