Lubricating properties
Hydraulic fluids - Influencing factors

These are the most difficult properties to assess, given the complexity of the factors involved. A machine to be lubricated represents a highly complex set of problems, and the interaction of parameters gives each case its own specific character. Compounding the problem is the fact that lubrication itself is not a well-known phenomenon. There are three basic types of lubrication associated with oil film thickness [4][9]:

• Hydrodynamic lubrication, which assumes a thick film;

• Elastohydrodynamic lubrication, when film thickness can be reduced under high applied loads;

• lubrication in smooth or boundary conditions when the film is thin.

Although the three types of lubrication are distinct, there is no clear dividing line between...