Load Calculations for Slewing Bearings with Eccentric Radial Loads

Single row four point contact ball bearings are routinely used as slewing bearings to take heavy loads under a combination of eccentric axial load and radial load for applications such as excavators, cranes, etc. The calculation method of the equivalent loads for the slewing bearings was introduced in SAE 2010-01- 1892.¹⁾ However, in this previous paper the calculation method could not be applied when an axial load does not exist. The specific case with no axial load but with a moment due to an eccentric radial load is introduced in this paper. When the eccentric radial load is applied, the bearing takes ball loads on both sides of each raceway. As a result, simple equations were obtained to calculate the static and dynamic equivalent loads, as well as the safety factors and bearing lives for slewing bearings under this condition. This method is used for the case when a bearing is mounted on a horizontal axis and loaded by a moment due to an eccentric radial load, such as large wheel change equipment for off-road heavy duty machinery.