In most applications, piston rings
are performing several functions. They contain and regulate
cylinder pressure, prevent oil blow-by, and to help regulate the
control of thermal changes in the unit. Each piston usually has
three types of rings; the compression ring, scraper ring, and oil
control ring. The compression ring prevents pressure lose as
the piston makes its way to the top of it's stroke. While
designed similarly to the compression ring, the scraper rings are
used to minimize oil build up between the compression ring and
oil ring. Finally, the oil control rings help to lubricate the
pistons, cylinder walls, rings and wrist pins, while also
maintaining thermal control by directing oil into the pistons.