Category:Piston

Pis"ton, n. Etym: [f. piston; cf. It. pistone piston, also pestone a Large pestle; all fr. L. pinsere, pistum, to pound, to stamp. See Pestle, pistil.] (mach.)

Defn: a sliding piece which either is moved by, or moves against, Fluid pressure. It usually consists of a short cylinder fitting Within a cylindrical vessel along which it moves, back and forth. It Is used in steam engines to receive motion from the steam, and in Pumps to transmit motion to a fluid; also for other purposes. Piston Head (steam eng.), that part of a piston which is made fast to the Piston rod. -- piston rod, a rod by which a piston is moved, or by which it Communicates motion. -- piston valve (steam eng.), a slide valve, consisting of a piston, Or connected pistons, working in a cylindrical case which is provided With ports that are traversed by the valve.