Hydro Static Bearing

Hydro static lubrication is essentially a form of hydrodynamic lubrication in which the metal surfaces are separated by a complete film of oil, but instead of being self-generated, the separating pressure is supplied by an external oil pump as shown in the fig below.

Hydro static lubrication depends on the inlet pressure of lube oil and clearance between the metal surfaces, whereas in hydrodynamic lubrication it depends on the relative speed between the surfaces, oil viscosity, load on the surfaces, and clearance between the moving surfaces.

Hydro static bearings require an external pressurized supply system and some type of flow restrictor. Also, under dynamic motions, hydro static bearings may display a pneumatic hammer effect due to fluid compressibility. However, and most importantly, the load and static stiffness of a hydro static bearing are independent of fluid viscosity; thus making this bearing type very attractive for application with non-viscous fluids, including gases and cryogenics.