Ring Nomenclature

At Hastings Manufacturing, we know piston rings, and want to pass that knowledge on to you. In this video we’re going to cover the basic ring types and terms, starting with the most basic.

A piston ring is a metal band used to control compression and oil in an engine. The primary function of a top compression ring is to seal compression gas and help in heat transfer. The second groove ring function is to help aid in scraping oil down the cylinder. The function of the oil control ring is to meter the amount of oil in the cylinder walls and provide ventilation for oil drain back. Piston rings are made from cast iron, ductile iron or steel. These rings can be chrome plated, moly inlay, nitride or PVD on the OD face of the rings.

And now for some terms that describe parts of the ring.

The ring diameter refers to the outside diameter of a piston ring when fitted to the engine bore. In comparison, this is the inside diameter or ID of a piston ring when compressed to actual bore size. The radial wall thickness is the material thickness between the inside and outside diameters of the ring.And the ring face is the portion of the ring that contacts the cylinder wall. Ring sides are the top and bottom surfaces of the piston ring. And the axial width is the area across the face of the ring. The free gap refers to the end clearance when the ring is in its free state. A compressed gap is the end clearance when the ring is compressed to bore diameter. And lastly, the side clearance is the distance between the axial width of the ring and the groove width.

Thanks for watching. We hope this video was helpful. Feel free to leave a comment on YouTube. And be sure to watch our other Tough Guy Tech Tip videos to learn more.

Tough Guy Tech Tips: Piston Rings

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