Purpose Nowadays, the use of Newtonian fluid as a lubricant is diminishing day by day, and the use of non-Newtonian fluids has gained importance. This paper presents an analysis of the static characteristics of Rayleigh step slider bearing lubricated with non-Newtonian Rabinowitsch fluid, which has not been studied so far. The purpose of this paper is to derive the modified Reynolds equation for Rabinowitsch fluids for two regions and to obtain the optimum bearing parameters for the Rayleigh step slider bearings. Design/methodology/approach The governing equations relevant to the problem under consideration are derived. The modified Reynolds equation is derived, and it is found to be highly non-linear and hence small perturbation method is adopted to find solution. Findings From this study it is found that there is an increase in the load-carrying capacity, pressure and frictional coefficients for dilatant fluids as compared to the corresponding Newtonian case. Further, for dilatant lubricants the maximum load-carrying capacity is attained for the slightly larger values of entry region length of Rayleigh step bearing as compared to Newtonian and pseudoplastic lubricants. Originality/value Rabinowitsch fluid is used for the study of lubrication characteristics of Rayleigh step bearings. The author believes that the paper presents these results for the first time.

In this paper, a theoretical study of the effect of surface roughness on the static characteristics of inclined plane slider-bearing lubricated with Rabinowitsch fluid is analysed. Christensen's stochastic theory for the lubrication of rough surfaces has been used for the derivation of generalised stochastic Reynolds-type equation. The two types of one-dimensional roughness patterns (Longitudinal and Transverse) are considered. Expressions for pressure, load carrying capacity, frictional force and coefficient of friction are obtained. It is found that the presence of transverse roughness pattern on the bearing surface increases pressure and load carrying capacity. Results are well agreement with smooth case.

In this paper the effect of surface roughness on squeeze film lubrication between circular stepped plates is analysed. The modified non-linear averaged Reynolds type equation is derived on the basis of Christensen's stochastic theory for rough surfaces for Rabinowitsch fluid model. Accordingly two types of one-dimensional surface roughness patterns, viz., azimuthal roughness pattern and radial roughness pattern are considered. Averaged non-linear Reynolds equation is solved by using the small perturbation method. Expressions are obtained for the load carrying capacity, squeeze film time. It is observed that the effect of azimuthal (radial) surface roughness pattern on squeeze film lubrication between circular stepped plates with Rabinowitsch fluid is to increase (decrease) the load carrying capacity and squeeze film time significantly as compared to the smooth case and the squeeze film performance improves (suffers) due to the use of dilatant (pseudo plastic) lubricants.