PRIN. OF INTERNAL COMBUSTION ENGINES - OD1619 LESSON 1/TASK 1
fit, shortening the breakin period, and an increase is overall engine longevity.
(b) The piston is anodized to produce a harder outside surface. Anodizing is
a process that produces a coating on the surface by electrolysis. The process
hardens the surface of the piston. This helps it resist picking up particles that
may become embedded in the piston, causing cylinder wall damage.
b.
Piston Rings.
(1) General (figure 18). Piston rings serve three important functions:
FIGURE 18. PURPOSE OF PISTON RINGS.
(a) They provide a seal between the piston and the cylinder wall to prevent
the force of the exploding gases from leaking into the crankcase from the
combustion chamber. This leakage is referred to as blowby. Blowby is detrimental
to engine performance because the force of the exploding gases will merely bypass
the piston rather than push it down. It also contaminates the lubricating oil.
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