Spherical and Conical Spiral Groove Bearings—Part I: Theory

Abstract

The performance of spherical and conical spiral groove bearings lubricated with a Newtonian, incompressible liquid is investigated. This work covers both complete and incomplete filling of the bearing gap with a liquid. In an incompletely filled bearing gap a gas-to-liquid interface occurs. Under radially eccentric operating conditions the location of the interface is related to the pressure distribution in the lubricating film. Part I treats a theory based on the smooth pressure concept. A perturbation method serves to determine the pressure distribution and, in the case of an incompletely filled bearing gap, also the location of the gas-to-liquid interface. From the pressure distributions, different for the two cases, formulas have been derived for the radial and axial load capacity. Comparison of the results obtained with this perturbation method with the results obtained with a numerical method lead to the conclusion that the former results can be used in practice as long as practically no cavitation occurs in the bearing. Previously reported experiments with spiral groove journal bearings confirm this. In spiral groove bearings the groove dimensions which lead to a satisfactory operation of the bearing are generally such that even with fairly marked eccentricities there is practically no occurrence of cavitation. Part II will treat the results obtained with the theory of Part I.