piston and piston ring

                                  PISTON

It is a cylindrical component which reciprocates inside engine cylinder.It is movable wall.It transmits power produce to crankshaft through connecting rod.It provide seal for the gasses.

Material: For piston desired properties are:

a)Uniform expansion at high temperature

b)Low weight

so aluminium alloy is best choice

                                                                      PISTON RING          

On piston there are gooves which hold piston rings.This include compression ring or gas ring,wiper ring and oil ring.There prime function is to seal the gas and circulate lubricating oil.

compression ring or gas ring:it is located closest to piston hesd.It’s function is to seal the gasses during high pressure.When  the gas is burnt huge pressure is generated.Which can leak to casing.

Wiper ring:It is piston ring with tapered face.It is used to further seal the combustion gass.It wipes out cylinder wall to remove excess oil.Combustion gass escaped from gass ring is stpped here.

Oil ring:It is located farthest from piston head.It provides thin film of oil.It allows flow of excess oil to reservoir.

        Piston ring gaps are placed 120 degree apart.

MATERIAL OF PISTON RING:It is subjected to continuous wear.It is made of fine grain cast iron Cast iron adheres to wall and it can be coated with other material to enhance durability.