Definition:
Lubricants may he defined as any chemical substance introduced between two moving or sliding surfaces with a view to reduce the frictional resistance between them is known as lubricants.
Lubrication may be defined as the “process by which frictional resistance gets reduces; with the use of lubricants is known as lubrication".
Explanation:
- When the moving surfaces are under very high pressure & high load & at high speed, a high temperature is obtained.
- And under these conditions liquid lubricants fails to stick & may decompose & even vaporized.
- To meet these extreme pressure conditions, special additives are added to mineral oils, these are called as extreme pressure additives.
- These extreme pressure additives form more durable film on the metal surfaces, which are capable of withstanding very high load & high temperature.
- Additives are: cl---chlorinated esters
p---tricrysyl phosphate .
s--- Sulphurised oils.
Function of lubricants: / Ideal lubricant:
- It reduces the frictional resistance, wear & tear of surfaces.
- It reduces the wastage of energy, (hereby increases the efficiency of machine
- It acts as coolant, thereby avoids the loss of energy. & maintains the dimension of the metal parts
- It acts as sealant there by avoid the escapes of gases from engine.
- It prevents the attack of the moisture & also acts as cleaner.