Piston Rings

Piston rings maintain close contact with the cylinder walls through their own spring tension, carrying out such functions as sealing in combustion gases, carrying heat away from the pistons by thermal conduction, and controlling the thickness of the lubricating oil film on the cylinder wall.

They must perform these functions under the severe conditions that occur in combustion chambers, while also playing the important roles of preventing seizure and minimizing wear on cylinder liners.