Piston Ring : An Essential Auto Part

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An internal combustion engine is a heat engine in which combustion (burning of fuel) takes place inside the cylinder which generate a high temperature and pressure force which further used for useful work. This function of IC engine achieved by various parts working together. These parts are bolted together and the combination of all these parts is known as engine. Piston ring is one of the essential auto part. Today I am going to tell you about this ring, its function, its types any many other facts related about it. So lets start.

Piston is a major part of an IC engine. It forms a movable boundary. When fuel burns inside the cylinder, it applied a pressure force on the piston which moves it downward and converts thermal energy into mechanical energy.

Pistons are equipped with some metal rings which performs many functions. These rings are known as piston rings. Today we will learn about requirement, function and types of these rings.

Piston Ring : Requirements, Functions and Types

Piston Rings:


Piston forms a movable boundary into an engine cylinder. If the piston is too tight, it does not move freely inside the cylinder when the pressure force applied during power stroke and if it is too loose it would leaks the pressure force. For proper functioning of an IC engine, piston should form a intermediate fit which provide a good sealing fit and less friction resistance between piston and cylinder wall. These requirements fulfilled by piston rings.
It consist mainly three rings. The first one is known as compression rings, middle one is known as wiper ring or intermediate ring and the last one is known as oil rings. These rings are mainly made by cast iron of fine grain and sometimes by alloy steel.

Function of Piston Rings:

  • To provide good sealing between piston and engine cylinder.
  • To regulate the amount of lubricant into engine cylinder.
  • To provide proper lubrication.
  • To transfer heat of piston through engine wall and fins.
  • To minimize friction between piston and engine wall.


As we previously mentioned, piston rings consist three types of rings. These are:

Compression Ring: It is upper most ring which is closest to the piston head. It provides a proper sealing between piston and engine cylinder. When the charge ignited, it applied a pressure force on piston. These combustion gases forces the piston toward crankshaft. They travel through the grooves created into compression ring where it forces the compression ring toward cylinder wall to form an air tight seal.

Intermediate or Wiper Ring: As the name implies, it is placed into groove cut between compression ring and oil ring. There are mainly two function of wiper ring. The first one is to help compression ring to create proper sealing and the other one is to wipe out excess lubrication oil provided by the oil ring.

Oil Ring: It is the bottom most ring in the set of these rings. The oil ring provides lubrication oil through its grooves to reduce friction between piston and cylinder. Oil ring is provided in four stroke engineTwo stroke engines does not contains oil ring due to mist lubrication system.

This is all about piston rings requirements, functions and its types. If you have any query regarding this article, ask by commenting. If you like this article, don’t forget to share it with your friends. Subscribe our website for more informative articles.

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