PRIN. OF INTERNAL COMBUSTION ENGINES - OD1619 LESSON 1/TASK 1
(b) The Oil Control Ring. The oil control ring prevents the engine's
lubrication oil from getting into the combustion chamber.
(3) Configurations. Piston rings are arranged on the pistons in three basic
configurations. They are:
(a) The threering piston (figure 20, view A) has two compression rings near
the head, followed by one oil control ring. This is the most common piston ring
configuration.
FIGURE 20. CONFIGURATIONS OF PISTON RINGS.
(b) The fourring piston (figure 20, view 8) has three compression rings near
the head, followed by one oil control ring. This configuration is common in diesel
engines because they are more prone to blowby, due to the much higher pressures
generated during the power stroke.
(c) The fourring piston (figure 20, view c) has two compression rings near
the head, followed by two oil control rings. The bottom oil control ring may be
located above or below the piston pin.
This is not a very common configuration in current engine design. In addition to
the configurations mentioned, there are some diesel engines that use five or more
piston rings on each piston to control the higher operating pressures.
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