The Effect of PISTON DESIGN on PISTON-RING STICKING

Bench tests for pistons, when properly correlated with actual engine operating conditions, can be used for heat-flow and piston temperature determinations, and will be useful in piston design.

Definite control of heat flow to rings is necessary in diesel iron pistons and can best be obtained by limiting the area of the cross-section immediately above the top ring or back of all rings.

Rings are only 65% as effective as lands and the piston skirt for transferring heat from the piston to the cylinder wall.

The thermal break between the piston surface and cylinder wall is the major restriction to heat flow through the piston.

Proper use of ribs in the piston head improves the conductivity of the piston and promotes uniform heat distribution in a cast-iron piston with a minimum of material.