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- Les guides de soupape servent à guider précisément les soupapes dans la culasse des moteurs thermiques. Ils permettent ainsi un bon contact entre les soupapes d'admission et d'échappement et leur siège respectif garantissant le bon fonctionnement du moteur. (fr)
- In most types of reciprocating engines, a valve guide is provided for each poppet valve in the cylinder head. Along with the valve spring, it serves to positively locate the valve so that it may make proper contact with the valve seat. A valve guide is a cylindrical piece of metal, pressed or integrally cast into the cylinder head, with the valve reciprocating inside it. Guides also serve to conduct heat from the combustion process out from the exhaust valve and into the cylinder head where it may be taken up by the cooling system. Bronze is commonly used, as is steel; a balance between stiffness and wear on the valve is essential to achieve a useful service life. The clearance between the inner diameter of the valve guide and the outer diameter of the poppet valve stem is critical for the proper performance of an engine. If there is too little clearance, the valve may stick as oil contaminants and thermal expansion become factors. If there is too much clearance, the valve may not seat properly and excessive oil consumption can occur. Over time, the inner diameter of the valve guide and the outer diameter of the valve stem may become worn. In the 1980s, many U.S. production engine remanufacturers began reaming valve guides, rather than replacing them, as part of their remanufacturing process. They found that by reaming all the valve guides in a head to one standard size (typically 0.008 in. diametrically oversized), and installing remanufactured engine valves having stems that are also oversized, a typical engine head can be remanufactured in much less time. Since the reaming process leaves the valve guide with a much better surface finish and shape than typical replacement guides, and since the oversize valves often have chrome plated stems, remanufacturers also discovered that valve train warranty issues are virtually eliminated. Studies have been conducted which show that through the proper selection of the reamer and reaming process, valves guides can be quickly and efficiently reamed to a consistently repeatable size. (en)
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- 3869 (xsd:nonNegativeInteger)
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- Les guides de soupape servent à guider précisément les soupapes dans la culasse des moteurs thermiques. Ils permettent ainsi un bon contact entre les soupapes d'admission et d'échappement et leur siège respectif garantissant le bon fonctionnement du moteur. (fr)
- In most types of reciprocating engines, a valve guide is provided for each poppet valve in the cylinder head. Along with the valve spring, it serves to positively locate the valve so that it may make proper contact with the valve seat. A valve guide is a cylindrical piece of metal, pressed or integrally cast into the cylinder head, with the valve reciprocating inside it. Guides also serve to conduct heat from the combustion process out from the exhaust valve and into the cylinder head where it may be taken up by the cooling system. Bronze is commonly used, as is steel; a balance between stiffness and wear on the valve is essential to achieve a useful service life. (en)
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- Guide de soupape (fr)
- Valve guide (en)
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