what is a piston ring
The piston ring (PR) is a split band pressed against the wall of the cylinder by springs (S) mounted in the inner junk ring (JR). The tongue (T) maintains the seal as the ring expands and splits apart. Spring-loaded piston rings. A pair of piston rings mounted on a 47mm two-stroke cycle scooter piston.A piston ring is a split ring that fits into a groove on the outer diameter of a piston in a reciprocating engine such as an internal combustion engine or steam engine. Sealing the combustion chamber so that there is no transfer of gases from the combustion chamber to the crank. 2  Supporting heat transfer from the piston to the cylinder wall. 3  Regulating engine oil consumption.