Pistoncylinder

A pistoncylinder refers to a mechanical assembly consisting of a cylindrical chamber (the cylinder) and a movable element (the piston) that travels within it. The pair is used to convert energy between fluid or gas pressure and linear motion, or to convert linear motion into pressure. The cylinder typically includes the bore, end caps, and ports for fluid entry and exit; the piston, mounted on a rod, slides inside the bore and is sealed by rings or other seals to minimize leakage and reduce friction.

Operation relies on pressure acting on the piston area. Pressurized fluid or combustion gases apply a force equal to pressure times piston area, generating linear motion. In internal combustion engines, expanding combustion gas pushes the piston, with motion transferred via a connecting rod to a crankshaft to produce rotary motion. In hydraulic or pneumatic systems, external devices receive the piston's linear motion to perform work.

Types of pistoncylinders include single-acting cylinders, where pressure produces motion in one direction and movement is reset by external forces, and double-acting cylinders, which use pressure on both sides to create bidirectional motion. Cylinders vary in bore size, stroke length, mounting, and sealing arrangements, and are found in a wide range of machinery beyond engines, such as hydraulic actuators, pneumatic actuators, and pumps.

Materials and design considerations emphasize strength, wear resistance, and heat management. Common materials include aluminum alloys for light-duty applications and steel or cast iron for higher strength. Proper lubrication, sealing, and alignment are essential to minimize wear and ensure reliable performance.