Lubrication modes hydrodynamic

This dimensionless term is known as the hydrodynamic factor , where Fig. 8.2 represents the Stribeck curve in the log scale and shows that a compromise must be made with respect to lubricant viscosity, between the friction losses in the region of hydrodynamic (HD) lubrication, and bearing wear when passing through the regime of mixed friction. Both hydrodynamic and hydrostatic bearings operate with infinite service life below some critical value of load and above a critical value of speed assuming other modes of wear such as corrosion and erosion are not experienced. 

In this book we shall begin with an examination of hydrodynamic lubrication. If there is a mode of real lubrication behavior which approaches the ideal, it is simple hydrodynamic lubrication. There is no contact of the solid surfaces and therefore no wear in the generally accepted sense the friction is that arising from the viscous shear of the lubricating fluid. The part that the viscosity and the density of the lubricating fluid plays in hydrodynamic lubrication leads us from engineering physics to the physical chemistry of liquids. 

---