Characteristics of Outwardly Pumping Spherical Spiral Groove Bearings : Part 2 Stability

Abstract

The stability characteristics of outwardly pumping spherical spiral groove bearings lubricated with incompressible liquid are investigated. The resultant bearing forces induced by small vibrations of a rotor under radially unloaded conditions are obtained. The bearing parameters have been optimized in search of the maximum axial load capacity, and then in search of the maximum radial stiffness. The stability characteristics of outwardly pumping spherical spiral groove bearings are compared with those of inwardly pumping ones. Experimental results are in good agreement with the theoretical ones. The conclusions are as follows. Although the maximum axial load capacity of outwardly pumping bearings is a fraction of that of inwardly pumping ones, outwardly pumping bearings are as stable as inwardly pumping ones. Generally, the stability threshold when a grooved member is rotating is higher than when a smoothed member is rotating.