pistones

Pistones (pistons) are cylindrical components that reciprocate within an engine cylinder, forming a gas-tight seal with the cylinder wall via piston rings. The up-and-down motion of the piston, driven by combustion or steam pressure, is converted into rotational motion by the connecting rod and crankshaft.

Pistons are typically made from aluminum alloys for light weight and good heat conductance; high-performance or heavy-duty engines may use forged aluminum or steel. The piston crown shape can be flat-topped, domed, or dished to tailor compression ratio and flame front.

Attached to the piston is a piston pin (gudgeon pin) that connects to the connecting rod. Piston rings seal the combustion chamber and regulate oil. Modern engines usually use a three-ring pack: top compression ring, second compression or scraper ring, and an oil control ring. The rings ride in grooves called ring lands.

During operation, pistons experience high temperature, pressure, and thermal expansion; proper lubrication and clearances are essential to prevent scuffing, ring sticking, or seizure. Common issues include ring wear, piston slap in worn cylinders, and piston crown damage from detonation or overheating.

Beyond internal combustion engines, pistons are used in steam engines, hydraulic cylinders, and air compressors. The development of the piston has been central to engine design since the 19th century, with advances in alloy technology, coatings, and manufacturing improving efficiency and durability.