Hydrodynamic Lubrication:

Cont oil film due to moving surfaces. Film due to motion of the moving parts. Journal bearing

Hydrostatic Lubrication:

Oil film doesn’t form naturally but pressure needs to be applied externally. Crosshead bearing

Boundary Lubrication:

Thin film between closely met surfaces. Contact might have been there.

Electrohydrodynamic lubrication:

Oil wedge thickness changes due to elastic deformation of the mating surfaces. Between gears

1. *Boundary Lubrication*:

   – This occurs when a thin layer of lubricant is present between two surfaces, preventing direct metal-to-metal contact. It is common in conditions where full fluid lubrication is not achievable, such as during start-up or shutdown.

2. *Hydrodynamic Lubrication*:

   – In this type, a full film of lubricant separates the moving surfaces completely. This film is maintained by the movement of the surfaces, creating a pressure that supports the load. It is typical in high-speed rotating machinery like main engines and shaft bearings.

3. *Electrohydrodynamic Lubrication*:

   – This lubrication occurs in rolling contacts, such as those found in ball and roller bearings. The lubricant film is thin, but due to the elastic deformation of the surfaces, it can still carry high loads.

4. *Mixed Lubrication*:

   – This is a combination of boundary and hydrodynamic lubrication, where both thin and thick films of lubricant coexist. It usually occurs during the transition between boundary and hydrodynamic lubrication phases.

5. *Grease Lubrication*:

   – Grease is used where oil lubrication is impractical or where the machinery is exposed to the elements and contamination. It is commonly used in bearings, seals, and other components that require infrequent lubrication.

6. *Oil Mist Lubrication*:

   – This method involves dispersing a fine mist of oil into the air, which then lubricates the machinery as it condenses on the surfaces. It is often used for high-speed or high-temperature applications where traditional lubrication methods might fail.

7. *Splash Lubrication*:

   – In this system, parts of the machinery splash oil from a reservoir onto moving components. It is commonly used in small engines and gearboxes.

8. *Forced Lubrication*:

   – Oil is pumped under pressure to critical parts of the machinery to ensure consistent lubrication. This type is typically used in large engines and complex machinery where reliable lubrication is crucial.