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class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Piston ring</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 24 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-24" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">24 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AD%D9%84%D9%82%D8%A9_%D9%83%D8%A8%D8%A7%D8%B3" title="حلقة كباس – Arabic" lang="ar" hreflang="ar" data-title="حلقة كباس" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%9F%D0%BE%D1%80%D1%88%D0%BD%D0%B5%D0%B2%D1%8B%D1%8F_%D0%BA%D0%BE%D0%BB%D1%8C%D1%86%D1%8B" title="Поршневыя кольцы – Belarusian" lang="be" hreflang="be" data-title="Поршневыя кольцы" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-bo mw-list-item"><a href="https://bo.wikipedia.org/wiki/%E0%BD%A6%E0%BE%B2%E0%BD%B4%E0%BD%96%E0%BC%8B%E0%BD%82%E0%BD%91%E0%BD%B4%E0%BD%96%E0%BC%8D" title="སྲུབ་གདུབ། – Tibetan" lang="bo" hreflang="bo" data-title="སྲུབ་གདུབ།" data-language-autonym="བོད་ཡིག" data-language-local-name="Tibetan" class="interlanguage-link-target"><span>བོད་ཡིག</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Segment_(mec%C3%A0nica)" title="Segment (mecànica) – Catalan" lang="ca" hreflang="ca" data-title="Segment (mecànica)" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/P%C3%ADstn%C3%AD_krou%C5%BEek" title="Pístní kroužek – Czech" lang="cs" hreflang="cs" data-title="Pístní kroužek" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Olieskrabering" title="Olieskrabering – Danish" lang="da" hreflang="da" data-title="Olieskrabering" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Kolbenring" title="Kolbenring – German" lang="de" hreflang="de" data-title="Kolbenring" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Segmento_(mec%C3%A1nica)" title="Segmento (mecánica) – Spanish" lang="es" hreflang="es" data-title="Segmento (mecánica)" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%B1%DB%8C%D9%86%DA%AF_%D9%BE%DB%8C%D8%B3%D8%AA%D9%88%D9%86" title="رینگ پیستون – Persian" lang="fa" hreflang="fa" data-title="رینگ پیستون" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Segmentation_(m%C3%A9canique)" title="Segmentation (mécanique) – French" lang="fr" hreflang="fr" data-title="Segmentation (mécanique)" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%ED%94%BC%EC%8A%A4%ED%86%A4_%EB%A7%81" title="피스톤 링 – Korean" lang="ko" hreflang="ko" data-title="피스톤 링" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Fascia_elastica" title="Fascia elastica – Italian" lang="it" hreflang="it" data-title="Fascia elastica" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Zuigerveer" title="Zuigerveer – Dutch" lang="nl" hreflang="nl" data-title="Zuigerveer" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%83%94%E3%82%B9%E3%83%88%E3%83%B3%E3%83%AA%E3%83%B3%E3%82%B0" title="ピストンリング – Japanese" lang="ja" hreflang="ja" data-title="ピストンリング" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Pier%C5%9Bcienie_t%C5%82okowe" title="Pierścienie tłokowe – Polish" lang="pl" hreflang="pl" data-title="Pierścienie tłokowe" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Segment_(piston)" title="Segment (piston) – Romanian" lang="ro" hreflang="ro" data-title="Segment (piston)" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9F%D0%BE%D1%80%D1%88%D0%BD%D0%B5%D0%B2%D1%8B%D0%B5_%D0%BA%D0%BE%D0%BB%D1%8C%D1%86%D0%B0" title="Поршневые кольца – Russian" lang="ru" hreflang="ru" data-title="Поршневые кольца" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Piestov%C3%BD_kr%C3%BA%C5%BEok" title="Piestový krúžok – Slovak" lang="sk" hreflang="sk" data-title="Piestový krúžok" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%9A%D0%B0%D1%80%D0%B8%D0%BA%D0%B5" title="Карике – Serbian" lang="sr" hreflang="sr" data-title="Карике" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Kolvring" title="Kolvring – Swedish" lang="sv" hreflang="sv" data-title="Kolvring" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Piston_sekman%C4%B1" title="Piston sekmanı – Turkish" lang="tr" hreflang="tr" data-title="Piston sekmanı" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9F%D0%BE%D1%80%D1%88%D0%BD%D0%B5%D0%B2%D0%B5_%D0%BA%D1%96%D0%BB%D1%8C%D1%86%D0%B5" title="Поршневе кільце – Ukrainian" lang="uk" hreflang="uk" data-title="Поршневе кільце" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/V%C3%B2ng_g%C4%83ng" title="Vòng găng – Vietnamese" lang="vi" hreflang="vi" data-title="Vòng găng" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E6%B4%BB%E5%A1%9E%E7%8E%AF" title="活塞环 – Chinese" lang="zh" hreflang="zh" data-title="活塞环" data-language-autonym="中文" data-language-local-name="Chinese" 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class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Part of a reciprocating engine</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:47mm_piston_rings.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/12/47mm_piston_rings.jpg/220px-47mm_piston_rings.jpg" decoding="async" width="220" height="95" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/12/47mm_piston_rings.jpg/330px-47mm_piston_rings.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/12/47mm_piston_rings.jpg/440px-47mm_piston_rings.jpg 2x" data-file-width="1109" data-file-height="480" /></a><figcaption>Two piston rings mounted on a two-stroke engine piston. The ring gap for the bottom ring is visible in the centre of the image.</figcaption></figure> <p>A <b>piston ring</b> is a metallic split ring that is attached to the outer diameter of a <a href="/wiki/Piston" title="Piston">piston</a> in an <a href="/wiki/Internal_combustion_engine" title="Internal combustion engine">internal combustion engine</a> or <a href="/wiki/Steam_engine" title="Steam engine">steam engine</a>. </p><p>The main functions of piston rings in engines are: </p> <ol><li>Sealing the <a href="/wiki/Combustion_chamber" title="Combustion chamber">combustion chamber</a> so that there is minimal loss of gases to the crank case.</li> <li>Improving heat transfer from the piston to the <a href="/wiki/Cylinder_(engine)" title="Cylinder (engine)">cylinder</a> wall.</li> <li>Maintaining the proper quantity of the oil between the piston and the cylinder wall</li> <li>Regulating engine oil consumption by scraping oil from the cylinder walls back to the sump.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup></li></ol> <p>Most piston rings are made from <a href="/wiki/Cast_iron" title="Cast iron">cast iron</a> or <a href="/wiki/Steel" title="Steel">steel</a>. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Design">Design</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Piston_ring&action=edit&section=1" title="Edit section: Design"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Fasce_eleastiche.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/98/Fasce_eleastiche.svg/220px-Fasce_eleastiche.svg.png" decoding="async" width="220" height="287" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/98/Fasce_eleastiche.svg/330px-Fasce_eleastiche.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/98/Fasce_eleastiche.svg/440px-Fasce_eleastiche.svg.png 2x" data-file-width="766" data-file-height="1000" /></a><figcaption>Piston ring configurations:<br /> A) Rectangular section<br /> B) Barrel face<br /> C) keystone<br /> D) Torsional twist<br /> E) Taper face<br /> F) Dykes<br /> Which also differ for the type of retainer band:<br /> Y) Behind-band<br /> X) Above or under-band<br /> Or for the ends that work without firm stops:<br /> K) Step<br /> J) Oblique<br /> W) Oblique with step</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Piston_ring_illustrated.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d4/Piston_ring_illustrated.png/220px-Piston_ring_illustrated.png" decoding="async" width="220" height="236" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d4/Piston_ring_illustrated.png/330px-Piston_ring_illustrated.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d4/Piston_ring_illustrated.png/440px-Piston_ring_illustrated.png 2x" data-file-width="553" data-file-height="592" /></a><figcaption>Piston ring. The piston ring (PR) is a split band pressed against the wall of the cylinder by springs (S) mounted in the inner "junk ring" (JR). The tongue (T) maintains the seal as the ring expands and splits apart.</figcaption></figure> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-More_citations_needed_section plainlinks metadata ambox mbox-small-left ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/Piston_ring" title="Special:EditPage/Piston ring">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed.</span> <span class="date-container"><i>(<span class="date">December 2019</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <p>Piston rings are designed to seal the gap between the piston and the cylinder wall.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> If this gap were too small, thermal expansion of the piston could mean the piston seizes in the cylinder, causing serious damage to the engine. On the other hand, a large gap would cause insufficient sealing of the piston rings against the cylinder walls, resulting in excessive <a href="/wiki/Blow-by" class="mw-redirect" title="Blow-by">blow-by</a> (combustion gases entering the crankcase) and less pressure on the piston, reducing the power output of the engine. </p><p>The sliding motion of the piston ring inside the cylinder wall causes friction losses for the engine. The friction caused by piston rings is approximately 24% of the total mechanical friction losses for the engine.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Federal_Mogul,_Carboglide_4-0" class="reference"><a href="#cite_note-Federal_Mogul,_Carboglide-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> The design of the piston rings is therefore a compromise between minimising friction while achieving good sealing and an acceptable lifespan. </p><p>Lubrication of piston rings is difficult and has been a driving force to improvements in the quality of <a href="/wiki/Motor_oil" title="Motor oil">motor oil</a>. The oil must survive high temperatures and harsh conditions with a high-speed sliding contact. Lubrication is particularly difficult as the rings have an oscillating motion rather than continuous rotation (such as in a bearing journal). At the limits of piston movement, the ring stops and reverses direction. This disrupts the normal oil wedge effect of a <a href="/wiki/Hydrodynamic_bearing" class="mw-redirect" title="Hydrodynamic bearing">hydrodynamic bearing</a>, reducing the effectiveness of the lubrication. </p><p>Rings are also sprung to increase the contact force and to maintain a close seal. The spring force is provided by either the stiffness of the ring itself or by a separate spring behind the seal ring. </p><p>It is important that rings float freely in their grooves within the piston, so that they can stay in contact with the cylinder.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Rings binding in the piston, usually due to a build-up of either combustion products or a breakdown of the lubricating oil, can cause engine failure and is a common cause of failure for diesel engines.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2019)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading3"><h3 id="Number_of_rings">Number of rings</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Piston_ring&action=edit&section=2" title="Edit section: Number of rings"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Sealing is often achieved by multiple rings, each with their own function, using a metal-on-metal sliding contact. Most pistons have at least two piston rings per cylinder. </p><p>Automotive piston engines typically have three rings per cylinder.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> The top two rings—known as <i>compression rings</i>—are primarily for sealing the combustion chamber. The bottom ring—known as the <i>oil control ring</i>—is primarily for controlling the supply of oil to the cylinder wall, in order to lubricate the piston skirt and the oil control rings.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Ring_construction">Ring construction</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Piston_ring&action=edit&section=3" title="Edit section: Ring construction"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The compression rings in an automotive engine typically have a rectangular or <a href="/wiki/Keystone_(architecture)" title="Keystone (architecture)">keystone</a> shaped cross-section. The upper compression ring typically has a barrel profile for the periphery, while the lower compression ring typically has a taper napier facing. Some engines also use a taper facing for the top ring, and simple plain-faced rings were used in the past. </p><p>Oil control rings are typically made from either a single piece of cast iron, multiple pieces of steel, or steel/iron with a helical spring backing to create the tension required for a close seal. Cast iron oil rings and rings with a helical spring backing have two scraping lands of various detailed form. On the other hand, multi-piece steel oil control rings usually consist of two thin steel rings (called <i>rails</i>) with a spacer-expander spring between them to keep the two rails apart and provide radial pressure. </p><p>The gap in the piston ring compresses to a few thousandths of an inch when inside the cylinder bore. Ring gap shapes include square cut, angle cut, tite joint, step cut, hook step and mitre step.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Piston_ring&action=edit&section=4" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Horizontal_steam_engine.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/00/Horizontal_steam_engine.png/220px-Horizontal_steam_engine.png" decoding="async" width="220" height="143" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/00/Horizontal_steam_engine.png/330px-Horizontal_steam_engine.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/00/Horizontal_steam_engine.png/440px-Horizontal_steam_engine.png 2x" data-file-width="788" data-file-height="511" /></a><figcaption>Steam engine with 3 piston rings at location D</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Piston_rings.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/93/Piston_rings.jpg/220px-Piston_rings.jpg" decoding="async" width="220" height="242" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/93/Piston_rings.jpg/330px-Piston_rings.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/93/Piston_rings.jpg/440px-Piston_rings.jpg 2x" data-file-width="1530" data-file-height="1680" /></a><figcaption>Spring-loaded piston rings</figcaption></figure> <p>Early steam engines used a hemp packing to seal the combustion chamber,<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> which caused high frictional resistance and did not provide a very effective seal. </p><p>The first use of a piston ring in the cylinders of a steam engine appears in 1825 by <a href="/wiki/Neil_Snodgrass" title="Neil Snodgrass">Neil Snodgrass</a>, a Glasgow engineer and mill-owner, for use in his own machines. This used springs to keep the seal steam-tight. From use within the mill this was experimented on the steamer <a href="/wiki/The_Caledonia_(paddle_steamer)" class="mw-redirect" title="The Caledonia (paddle steamer)">"Caledonia"</a> which plied the <a href="/wiki/Gareloch" class="mw-redirect" title="Gareloch">Gareloch</a>.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p><p>The modern design of a metallic split-ring was invented by <a href="/wiki/John_Ramsbottom_(engineer)" title="John Ramsbottom (engineer)">John Ramsbottom</a> in the 1850s. Ramsbottom's initial design in 1852 was a circular shape, however these wore unevenly and were not successful. In 1854, a revised design was claimed to have a lifespan of up to 4,000 mi (6,437 km).<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> This was based on the discovery that a perfectly round (prior to installation) ring with a split in it does not exert an even pressure on the cylinder walls once installed. The revised piston ring was manufactured to an out-of-round shape, so that it would exert even pressure once installed in the cylinder. An 1855 patent documented this change. The switch to metallic piston rings dramatically reduced the frictional resistance, the leakage of steam, and the mass of the piston, leading to significant increases in power and efficiency and longer maintenance intervals. </p> <div class="mw-heading mw-heading2"><h2 id="Engine_wear">Engine wear</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Piston_ring&action=edit&section=5" title="Edit section: Engine wear"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-More_citations_needed_section plainlinks metadata ambox mbox-small-left ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/Piston_ring" title="Special:EditPage/Piston ring">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed.</span> <span class="date-container"><i>(<span class="date">December 2019</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <p>Piston rings are subject to wear as they move up and down the cylinder bore, due to their own inherent load and due to the gas load acting on the ring. To minimize this, they are made of wear-resistant materials, such as cast iron and steel, and are coated or treated to enhance the wear resistance. Coatings used in modern motorcycles include <a href="/wiki/Chromium" title="Chromium">chromium</a>,<sup id="cite_ref-federalmogul.com_13-0" class="reference"><a href="#cite_note-federalmogul.com-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Nitride" title="Nitride">nitride</a>,<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> or ceramic coating made by <a href="/wiki/Plasma-enhanced_chemical_vapor_deposition" title="Plasma-enhanced chemical vapor deposition">plasma deposition</a><sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> or <a href="/wiki/Physical_vapor_deposition" title="Physical vapor deposition">physical vapour deposition</a> (PVD).<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> Most modern <a href="/wiki/Diesel_engine" title="Diesel engine">diesel engines</a> have top rings coated with a modified chromium coating (known as CKS or GDC),<sup id="cite_ref-federalmogul.com_13-1" class="reference"><a href="#cite_note-federalmogul.com-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup><sup class="noprint Inline-Template"><span style="white-space: nowrap;">[<i><a href="/wiki/Wikipedia:Link_rot" title="Wikipedia:Link rot"><span title=" Dead link tagged May 2020">dead link</span></a></i><span style="visibility:hidden; color:transparent; padding-left:2px">‍</span>]</span></sup> which has aluminium oxide or diamond particles respectively included in the chrome surface. </p><p>In two-stroke engines, the port design is also an important factor for the lifespan of the piston rings. </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Piston_ring&action=edit&section=6" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Cylinder_(engine)" title="Cylinder (engine)">Cylinder (engine)</a></li> <li><a href="/wiki/List_of_auto_parts" title="List of auto parts">List of auto parts</a></li> <li><a href="/wiki/Obturator_ring" title="Obturator ring">Obturator ring</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Piston_ring&action=edit&section=7" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20191119235438/http://korihandbook.federalmogul.com/en/section_6.htm">"General Principles"</a>. <i>www.federalmogul.com</i>. 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Retrieved <span class="nowrap">4 July</span> 2010</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.federalmogul.com&rft.atitle=Wear-Resistant+Peripheral+Coatings&rft_id=http%3A%2F%2Fwww.federalmogul.com%2Fkorihandbook%2Fen%2Fsection_44.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3APiston+ring" class="Z3988"></span></span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20120810201754/http://www.federalmogul.com/korihandbook/en/section_45.htm">"Wear-Resistant Peripheral Coatings"</a>. <i>www.federalmogul.com</i>. Archived from <a rel="nofollow" class="external text" href="http://www.federalmogul.com/korihandbook/en/section_45.htm">the original</a> on 10 August 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">4 July</span> 2010</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.federalmogul.com&rft.atitle=Wear-Resistant+Peripheral+Coatings&rft_id=http%3A%2F%2Fwww.federalmogul.com%2Fkorihandbook%2Fen%2Fsection_45.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3APiston+ring" class="Z3988"></span></span> </li> <li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20160706043351/http://www.grovercorp.com/assets/files/GROVER-ProductSheet.pdf">"Metallic piston rings product sheet"</a> <span class="cs1-format">(PDF)</span>. <i>www.grovercorp.com</i>. Archived from <a rel="nofollow" class="external text" href="http://www.grovercorp.com/assets/files/GROVER-ProductSheet.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 6 July 2016<span class="reference-accessdate">. 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combustion engine">Internal combustion engine</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div><i>Part of the <a href="/wiki/Car" title="Car">Automobile</a> series</i></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Engine_block" title="Engine block">Engine block</a> and<br /> rotating assembly</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Balance_shaft" title="Balance shaft">Balance shaft</a></li> <li><a href="/wiki/Block_heater" title="Block heater">Block heater</a></li> <li><a href="/wiki/Bore_(engine)" title="Bore (engine)">Bore</a></li> <li><a href="/wiki/Connecting_rod" title="Connecting rod">Connecting rod</a></li> <li><a href="/wiki/Crankcase" title="Crankcase">Crankcase</a></li> <li><a href="/wiki/Crankcase_ventilation_system" title="Crankcase ventilation system">Crankcase ventilation system (PCV valve)</a></li> <li><a href="/wiki/Crankpin" title="Crankpin">Crankpin</a></li> <li><a href="/wiki/Crankshaft" title="Crankshaft">Crankshaft</a></li> <li><a href="/wiki/Core_plug" title="Core plug">Core plug (freeze plug)</a></li> <li><a href="/wiki/Cylinder_(engine)" title="Cylinder (engine)">Cylinder</a> (<a href="/wiki/Cylinder_bank" class="mw-redirect" title="Cylinder bank">bank</a>, <a href="/wiki/Engine_configuration" title="Engine configuration">layout</a>)</li> <li><a href="/wiki/Engine_displacement" title="Engine displacement">Displacement</a></li> <li><a href="/wiki/Flywheel" title="Flywheel">Flywheel</a></li> <li><a href="/wiki/Firing_order" title="Firing order">Firing order</a></li> <li><a href="/wiki/Stroke_(engine)" title="Stroke (engine)">Stroke</a></li> <li><a href="/wiki/Main_bearing" title="Main bearing">Main bearing</a></li> <li><a href="/wiki/Piston" title="Piston">Piston</a></li> <li><a class="mw-selflink selflink">Piston ring</a></li> <li><a href="/wiki/Starter_ring_gear" title="Starter ring gear">Starter ring gear</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Valvetrain" title="Valvetrain">Valvetrain</a> and<br /> <a href="/wiki/Cylinder_head" title="Cylinder head">Cylinder head</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Flathead_engine" title="Flathead engine">Flathead layout</a></li> <li><a href="/wiki/Overhead_camshaft_engine" title="Overhead camshaft engine">Overhead camshaft layout</a></li> <li><a href="/wiki/Overhead_valve_engine" title="Overhead valve engine">Overhead valve (pushrod) layout</a></li></ul> <ul><li><a href="/wiki/Tappet" title="Tappet">Tappet / lifter</a></li> <li><a href="/wiki/Camshaft" title="Camshaft">Camshaft</a></li> <li><a href="/wiki/Chest_(mechanical_engineering)" title="Chest (mechanical engineering)">Chest</a></li> <li><a href="/wiki/Combustion_chamber" title="Combustion chamber">Combustion chamber</a></li> <li><a href="/wiki/Compression_ratio" title="Compression ratio">Compression ratio</a></li> <li><a href="/wiki/Head_gasket" title="Head gasket">Head gasket</a></li> <li><a href="/wiki/Rocker_arm" title="Rocker arm">Rocker arm</a></li> <li><a href="/wiki/Timing_belt_(camshaft)" title="Timing belt (camshaft)">Timing belt</a></li> <li><a href="/wiki/Poppet_valve" title="Poppet valve">Valve</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Forced_induction" title="Forced induction">Forced induction</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Blowoff_valve" title="Blowoff valve">Blowoff valve</a></li> <li><a href="/wiki/Boost_controller" title="Boost controller">Boost controller</a></li> <li><a href="/wiki/Intercooler" title="Intercooler">Intercooler</a></li> <li><a href="/wiki/Supercharger" title="Supercharger">Supercharger</a></li> <li><a href="/wiki/Turbocharger" title="Turbocharger">Turbocharger</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Fuel system</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Diesel_engine" title="Diesel engine">Diesel engine</a></li> <li><a href="/wiki/Petrol_engine" title="Petrol engine">Petrol engine</a></li> <li><a href="/wiki/Carburetor" title="Carburetor">Carburetor</a></li> <li><a href="/wiki/Fuel_filter" title="Fuel filter">Fuel filter</a></li> <li><a href="/wiki/Fuel_injection" title="Fuel injection">Fuel injection</a></li> <li><a href="/wiki/Fuel_pump" title="Fuel pump">Fuel pump</a></li> <li><a href="/wiki/Fuel_tank" title="Fuel tank">Fuel tank</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Ignition_system" title="Ignition system">Ignition</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ignition_magneto" title="Ignition magneto">Magneto</a></li> <li><a href="/wiki/Compression_ignition" class="mw-redirect" title="Compression ignition">Compression ignition</a></li> <li><a href="/wiki/Coil-on-plug_ignition" class="mw-redirect" title="Coil-on-plug ignition">Coil-on-plug</a></li> <li><a href="/wiki/Distributor" title="Distributor">Distributor</a></li> <li><a href="/wiki/Glow_plug_(diesel_engine)" class="mw-redirect" title="Glow plug (diesel engine)">Glow plug</a></li> <li><a href="/wiki/Ignition_coil" title="Ignition coil">Ignition coil</a></li> <li><a href="/wiki/Spark_plug" title="Spark plug">Spark plug</a></li> <li><a href="/wiki/Spark_plug_wires" title="Spark plug wires">Spark plug wires</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">Engine management</div></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Engine_control_unit" title="Engine control unit">Engine control unit (ECU)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">Electrical system</div></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Alternator_(automotive)" title="Alternator (automotive)">Alternator</a></li> <li><a href="/wiki/Automotive_battery" title="Automotive battery">Battery</a></li> <li><a href="/wiki/Dynamo" title="Dynamo">Dynamo</a></li> <li><a href="/wiki/Starter_(engine)" title="Starter (engine)">Starter motor</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Intake system</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Airbox" title="Airbox">Airbox</a></li> <li><a href="/wiki/Air_filter#Internal_combustion_engine_air_filters" title="Air filter">Air filter</a></li> <li><a href="/wiki/Idle_air_control_actuator" title="Idle air control actuator">Idle air control actuator</a></li> <li><a href="/wiki/Inlet_manifold" title="Inlet manifold">Inlet manifold</a></li> <li><a href="/wiki/MAP_sensor" title="MAP sensor">MAP sensor</a></li> <li><a href="/wiki/Mass_flow_sensor" title="Mass flow sensor">MAF sensor</a></li> <li><a href="/wiki/Throttle" title="Throttle">Throttle</a></li> <li><a href="/wiki/Throttle_position_sensor" title="Throttle position sensor">Throttle position sensor</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Exhaust_system" title="Exhaust system">Exhaust system</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Catalytic_converter" title="Catalytic converter">Catalytic converter</a></li> <li><a href="/wiki/Diesel_particulate_filter" title="Diesel particulate filter">Diesel particulate filter</a></li> <li><a href="/wiki/Exhaust_gas_temperature_gauge" title="Exhaust gas temperature gauge">EGT sensor</a></li> <li><a href="/wiki/Exhaust_manifold" title="Exhaust manifold">Exhaust manifold</a></li> <li><a href="/wiki/Muffler" title="Muffler">Muffler</a></li> <li><a href="/wiki/Oxygen_sensor#Automotive_applications" title="Oxygen sensor">Oxygen sensor</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Internal_combustion_engine_cooling" title="Internal combustion engine cooling">Cooling system</a></th><td class="navbox-list-with-group navbox-list navbox-even 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