A piston ring is a split ring that fits into a piston groove in a reciprocating engine such as an internal combustion engine.

The three main functions of piston rings in reciprocating engines are:

Sealing the combustion chamber so that there is no transfer of gases from the combustion chamber to the crank. Supporting heat transfer from the piston to the cylinder wall. Regulating engine oil consumption

Piston rings are small and relatively inexpensive parts working in a complex and very expensive engine. Unless the piston ring is functioning perfectly, the engine will lose efficiency with consequential reduction in power and increased fuel consumption.

Piston rings have a wide range of industrial applications. Regardless of whether they are used in aircraft, locomotive, car or a compressor they are responsible for the performance of the system in which they are used.