21 February 2016

What is lubrication? | Purpose | Types

Definition of Lubrication: 

To supply lubricating oil between the moving parts is simply termed as lubrication.

Friction is the force that resists relative motion between two bodies in contact. If friction didn't exist nothing would ever stop moving for this reason lubrication is necessary.

The function of lubricants is to reduce friction and heat. 

Purpose of Lubrication:

  • To reduce the frictional forces between the parts having relative motion 
  • To reduce the wear and tear of moving parts
  • Corrosion prevention
  • To cool the surfaces by carrying away the heat generated due to friction
  • To seal a space adjoining the surfaces such as piston rings and cylinder linear
  • To absorb the shocks 
  • Cleaning agent 
  • To help the piston rings to seal the gases inside the piston cylinder
  • Increase fuel economy by providing low friction surfaces

Advantages of lubrication in the engine parts:

  • Higher efficiency 
  • longer life
  • better reliability
  • less money spent on maintenance 

Parts of Engine Requires Lubrication:

The main parts of the engine which need lubrication are:
  • Main crankshaft bearings.
  • Big end bearings or crank pin.
  • Gudgeon in bearings.
  • Piston rings and cylindrical walls.
  • Timing gears. 
  • Camshaft and camshaft bearings.
  • Valve mechanism
  • Valve guide, valve tappets, rocker arms.
  • Governor and
  • Water pump bearing.
Any substance introduced between two moving or sliding surface with a view to reducing the frictional resistance between them is called lubricants.

Types of Lubricants :

Lubricants are at following three types.

1. Solid: graphic, mica etc
2. Semi-solid: grease
3. Liquid: mineral oil, vegetable oil, animal oil etc.

Graphite is often mixed with oil to lubricate automobile spring. Graphite is also used as a cylinder lubricant.

Grease is used for chassis lubrication.

Mineral oils are almost used for engine lubrication.
Grade of lubricants: Generally, lubricating oils are graded by their SAE (society of automotive engineers) viscosity number. 

5w,10w,20w SAE number lubricating oil are for winter use.
20,30,40 SAE number lubricating oil is for summer use.