Functions
> Lubrication reduces static and dynamic friction to a minimum and prevents wear.
> Remove heat, generated either within the bearing or from an outside source.
> Protect against corrosion
> Flush away contaminants.
> Dampen noise.
> In some cases, act as a sealant
Types of Lubrication
> Hydrodynamic Lubrication:- It is a full fluid film lubrication. The lubricant separates the rubbing surfaces by creating a very thin film Lubrication between the rubbing surfaces which are separated by a continuous unbroken oil film of adequate thickness. The pressure self generated due to the motion of the moving surfaces.
Example:Lubrication for Journal Bearing, Bottom End Bearing, Tilting Pad Thrust Bearing
> Hydrostatic Lubrication:- It is also a full thick film lubrication, similar to hydrodynamic lubrication except that the oil pressure is supplied by an external source.
Example: Lubrication for Crosshead Bearings, with attached pump
> Boundary Lubrication:- This type of lubrication is applied when a full-fluid film lubrication is not possible. The sliding surfaces are separated by only a thin film of lubricant. High friction between the surfaces and some degree of metal to metal contact occurs. Lubricant oil film decreases, until asperities of mating surfaces touch
> Elasto-hydrodynamic Lubrication:- Applies to line contact or nominal point between rolling or sliding surfaces, such as rolling contact bearings and meshing gear teeth. Thin film or squeeze film lubrication limits metal to metal contact. Elastic deformation of the metals occurs, and there is an effect of high pressure on the lubricant.
You can answer following questions
> What is the lubrication of crosshead bearing? (imp)
> Explain the different lubrication methods in marine engine
> What is the lubrication method of journal bearing? (Imp)