PRIN. OF INTERNAL COMBUSTION ENGINES - OD1619 LESSON 1/TASK 1
FIGURE 14. CONTROLLING PISTON EXPANSION.
(c) A variation of the splitskirt piston is the Tslot piston. The Tslot
piston is similar to the splitskirt piston, with the addition of a horizontal slot
that retards heat transfer from the piston head to the piston skirt.
(d) Some aluminum pistons have steel braces cast into them to control
expansion.
(4) Cam Grinding (figure 15 on the following page). By making the piston egg
shaped, it will be able to fit the cylinder better throughout its operational
temperature range. A piston of this configuration is called a camground piston.
Camground pistons are machined so that their diameter is smaller parallel to the
piston pin axis than it is perpendicular to it. When the piston is cold, it will
be big enough across the larger diameter to prevent rocking. As it warms up, it
will expand across its smaller diameter at a much higher rate than at its larger
diameter. This will tend to make the piston round at operating temperature.
Virtually all pistons in automotive applications are camground.
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