Lesson 1/Learning Event 1
Piston Rings
The rings on pistons do more than prevent gases from leaking between the piston and cylinder wall. They also
assist in cooling the piston and keep lubricant from entering the combustion chamber. They cool the piston by
transmitting heat from the piston to the cylinder block. Two types of rings, compression and oil-regulating, are
used.
FIGURE 22. PISTON RINGS.
Compression Rings. The main job of the compression rings is to prevent pressure in the combustion chamber
from leaking past the piston into the crankcase. Since the high pressures are created above the piston,
compression rings are located in the top piston ring grooves. Generally, at least two compression rings are
used.
Oil- Regulating or Oil-Control Rings. When an engine is running, a large amount of oil is being sprayed and
splashed on the cylinder walls and pistons. This oil is needed for cooling and lubricating purposes, but if it gets
into the combustion chamber, mechanical problems will develop. Oil that gets into the combustion chamber
will be burned and passed out the exhaust
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