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Difference between revisions of "Poppet valve"
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==Internal combustion engine== | ==Internal combustion engine== | ||
[[Image:Four stroke engine diagram.jpg|thumbnail|right|175px|Components of a typical, [[four stroke cycle]], DOHC piston engine:<br>(E) Exhaust [[camshaft]],<br>(I) Intake camshaft,<br>(S) [[Spark plug]],<br>(V) Valves,<br>(P) [[Piston]],<br>(R) [[Connecting rod]],<br>(C) [[Crankshaft]],<br>(W) Water jacket for coolant flow.]] | [[Image:Four stroke engine diagram.jpg|thumbnail|right|175px|Components of a typical, [[four stroke cycle]], DOHC piston engine:<br>(E) Exhaust [[camshaft]],<br>(I) Intake camshaft,<br>(S) [[Spark plug]],<br>(V) Valves,<br>(P) [[Piston]],<br>(R) [[Connecting rod]],<br>(C) [[Crankshaft]],<br>(W) [[Water jacket]] for coolant flow.]] | ||
''Poppet valves'' are used in most [[piston engine]]s to open and close the intake and exhaust [[cylinder head porting|ports]] in the [[cylinder head]]. The valve is usually a flat disk of metal with a long rod known as the ''valve stem'' out one end. The stem is used to push down on the valve and open it, with a spring generally used to close it when the stem is not being pushed on. [[Desmodromic valve]]s are closed by positive mechanical action instead of by a spring, and are used in some high speed [[motorcycle]] and auto racing engines, eliminating '[[valve float]]' at high [[RPM]]. | ''Poppet valves'' are used in most [[piston engine]]s to open and close the intake and exhaust [[cylinder head porting|ports]] in the [[cylinder head]]. The valve is usually a flat disk of metal with a long rod known as the ''valve stem'' out one end. The stem is used to push down on the valve and open it, with a spring generally used to close it when the stem is not being pushed on. [[Desmodromic valve]]s are closed by positive mechanical action instead of by a spring, and are used in some high speed [[motorcycle]] and auto racing engines, eliminating '[[valve float]]' at high [[RPM]]. | ||