Background: An abnormal micro/nano step bearing with the film thickness in the inlet zone
lower than that in the outlet zone registered in the patent is introduced based on the physical adsorption
technology. This bearing does not follow conventional hydrodynamic lubrication principles.
Objective: To introduce an abnormal-geometry micro step bearing for application in special cases.
Methods: The operation of the mentioned bearing is based on the physical adsorption of the lubricating
film to the bearing surface. The modified Reynolds equation for the analysis of this bearing is presented,
based on the flow equation for a nanoscale fluid flow.
Results: The calculation results showed that the mentioned bearing has a load-carrying capacity when
the lubricating film thickness and the size of the step of the bearing both are on the 1nm scale. The
physical adsorption of the lubricating film to the bearing surface has a significant effect on the bearing
Conclusion: The abnormal bearing in which the inlet film thickness is lower than the outlet film thickness,
can be developed based on the physical adsorption of the lubricating film. It requires the physical
adsorption of the film to the contacts in the inlet zone stronger than that in the outlet zone. The exemplary
calculation results for the load-carrying capacity of this bearing are presented. This bearing does
not follow conventional hydrodynamic lubrication principles, which rely on the convergent surface
separation or the surface squeezing. The surface separation in this bearing is indeed divergent.