A piston ring is a circular band located on the exterior of a piston in an engine that aids in heat transfer, seals the engine combustion chamber and normalizes an engine's consumption of oil. Piston rings are used in both combustion engines and steam engines.

Automotive Piston Rings

There are two types of piston rings in automobile engines, or combustion engines: compression rings and oil control rings. Compression rings seal the combustion chamber of an engine. Oil control rings lubricate the piston and the compression rings with oil.

Piston Ring Wear

Like other interior elements of combustion engines, piston rings are subject to wear. As a piston fires, piston rings move up and down within the piston chamber. Piston rings are made out of iron or steel and are not easily damaged. However, prolonged engine use can cause them to wear down.

Modified Piston Rings

Scraper rings are a type of oil control piston rings that are designed to maximize oil scraping efficiency. Scraper rings use some variation of a design that makes use of a recessed exterior that increases oil control. Examples of scraper rings include the taper faced napier ring and the taper faced closed gap scraper ring.

Care and Maintence of Piston Rings

The best way to prevent engine wear, including the wear of piston rings, is to ensure that the engine has enough oil of a sufficient quality. A dry, unlubricated engine will wear significantly faster than an engine that is well oiled. Piston rings can be treated with chemicals, coated with tin or copper or oxidized to delay wear and tear.

Piston Rings in Steam Engines

In steam engines, piston rings seal the steam compression chamber. The concept of oil control piston rings is not used in steam engine operation.

Source:

Piston Ring Handbook

Hastings Piston Rings

Resource:

Piston Ring Handbook