A Rational Approach for Determining Permissible Speed for Needle Roller Bearings

For most rolling element bearings used in practical applications, the permissible speed is defined as the bearing speed corresponding to a certain assumed limiting operating temperature in the bearing. Prediction of bearing permissible speed requires a thermal balance analysis considering 1) bearing heat generation (or torque) and 2) the heat dissipation of the bearing system, which is a function of ambient temperature, housing material and geometry and its heat transfer parameters.

Recent results of running torque measurement of needle roller bearings and other types of roller bearings have been reviewed and compared with the well known Palmgren's prediction. The experimentally based formula for bearing power loss for needle bearings is used in the heat balance analysis for determining bearing reference and permissible speed. The calculated reference speed is compared with the DIN calculated reference speed using Palmgren's formula. A simple heat dissipation analysis of bearing housing/shaft is also used in calculating permissible speed. Using this reference speed value for a particular bearing as input, the bearing permissible speed (for a particular set of operating conditions, i.e. load, oil flow rate and viscosity) can be determined using a computer program.