{"id":99919,"date":"2025-02-14T10:20:09","date_gmt":"2025-02-14T18:20:09","guid":{"rendered":"https:\/\/www.racingjunk.com\/news\/?p=99919"},"modified":"2025-02-14T10:22:05","modified_gmt":"2025-02-14T18:22:05","slug":"mechanically-speaking-how-clutch-flex-fans-work","status":"publish","type":"post","link":"https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/","title":{"rendered":"Mechanically Speaking: How Clutch &#038; Flex Fans Work"},"content":{"rendered":"<div data-carousel-extra='{\"blog_id\":1,\"permalink\":\"https:\\\/\\\/www.racingjunk.com\\\/news\\\/mechanically-speaking-how-clutch-flex-fans-work\\\/\"}' id='gallery-1' class='gallery galleryid-99919 gallery-columns-3 gallery-size-thumbnail'><figure class='gallery-item'>\n\t\t\t<div class='gallery-icon landscape'>\n\t\t\t\t<a href='https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-1-min\/'><img loading=\"lazy\" decoding=\"async\" width=\"150\" height=\"150\" src=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-1-min-e1739557187872-150x150.jpg\" class=\"attachment-thumbnail size-thumbnail\" alt=\"Mechanically Speaking: How Clutch &amp; Flex Fans Work\" aria-describedby=\"gallery-1-99921\" data-attachment-id=\"99921\" data-permalink=\"https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-1-min\/\" data-orig-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-1-min-e1739557187872.jpg\" data-orig-size=\"640,394\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"Mechanically Speaking: How Clutch &amp;#038; Flex Fans Work\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;&lt;a class=&quot;click__begin&quot;&gt;Click Here to Begin Slideshow&lt;\/a&gt;&lt;\/p&gt;\n&lt;p&gt;In the hypothetical world, a fan wouldn&amp;#8217;t be required if your car was constantly driven at high speeds (definitely an interesting concept, but not too practical).\u00a0 Airflow from the vehicle&amp;#8217;s velocity would be sufficient to allow for adequate air movement through the radiator surface, with the result being proper cooling. While this would be an ideal situation, it&amp;#8217;s seldom possible.\u00a0 Or realistic.\u00a0 Because of this, a fan of some sort becomes a necessity.\u00a0&lt;\/p&gt;\n&lt;p&gt;While electric fans are by far the most common today (here, an electric motor simply turns the fan on or off, depending upon a pre-determined temperature), many vehicles on the road today \u2013 particularly vintage examples &amp;#8212; still rely upon mechanical fans.&lt;\/p&gt;\n&lt;p&gt;There have been a number of mechanical engine-driven fan types used on passenger cars over the years \u2013 some fixed, some \u201cflexible\u201d.\u00a0 \u00a0\u00a0A fixed fan rotates constantly with the water pump shaft.\u00a0 On the other hand, a common thermal clutch fan operates by way of a viscous coupling. The fan clutch is a small fluid coupling bolted to the fan just behind the radiator. It incorporates a thermostatic device that controls the fan speed. This ensures that the fan will rotate at a speed that is sufficient to maintain engine cooling. Simultaneously, the thermostatic devise can disengage the fan when it is no longer needed (engine is cooled).&lt;\/p&gt;\n&lt;p&gt;So how does it work?\u00a0 The key is the clutch.\u00a0 It is engineered with a fluid coupling partially filled with a silicone-based fluid designed for just this purpose. Within the clutch, you\u2019ll find several passages (cavities), separated with a valve of sorts.\u00a0 On the nose of the clutch, you\u2019ll find either a coiled bimetal spring or a flat bimetal strip.\u00a0 As the temperature of the air passing over the radiator rises, the bimetal spring simply expands (actually, the coils unwind).\u00a0 In the case of the bimetal strip, it bends in or out depending upon the temperature.\u00a0 As the coils in the spring unwind (or in the case of a strip, bends or flexes), more silicone fluid is allowed to enter the fluid coupling.\u00a0 With more silicone fluid in place, the slip within the clutch is reduced.\u00a0 That means the fan is allowed to slowly rotate.\u00a0 As the temperature continues to rise, the coil will fully unwind (expand).\u00a0 Eventually, the clutch on the nose of the fan will become almost completely locked, which in turn allows the fan to draw the maximum amount of air through the radiator.\u00a0 As the air passing through the radiator cools (for example, driving at uninterrupted highway speeds), then the fan coupling decreases.\u00a0 Eventually, the fan slows and freewheels.\u00a0 This reduces noise, saves engine power and of course, improves fuel economy. Most fan clutches allow the fluid to drain into the [fluid] cavity when the engine is shut down.\u00a0 As a result, the clutch (and the fan) becomes engaged.\u00a0 When you start an engine, even from cold, it will take a minute or two for the clutch to slow down (hence the extra noise when the vehicle is first started \u2013 the fan is locked \u201con\u201d). It\u2019s not hard to see that the fan clutch is a simple but actually brilliant device.&lt;\/p&gt;\n&lt;p&gt;Simple flex fans have been in use for a long period of time too.\u00a0 They reduce their pitch as engine RPM increases (or more correctly, as pulley speed increases).\u00a0 These are even simpler devices than clutch fans. Here, the blades (stainless steel, aluminum, fiberglass or sometimes composites) rely upon centrifugal force to perform the work. As pointed out above, the pitch of the respective blades flatten as the engine speed increases. At low engine speed, the fan draws the maximum amount of air through the radiator as possible, but as the engine increases (and theoretically, the vehicle speed increases), the fan flattens.\u00a0 This draws in little air and consumes less power to turn.\u00a0 The flex fan is an extremely simple device.\u00a0 More in the accompanying photos:&lt;\/p&gt;\n&lt;p&gt;&lt;a class=&quot;click__begin&quot;&gt;Click Here to Begin Slideshow&lt;\/a&gt;&lt;\/p&gt;\n\" data-medium-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-1-min-e1739557187872-300x185.jpg\" data-large-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-1-min-e1739557187872.jpg\" \/><\/a>\n\t\t\t<\/div>\n\t\t\t\t<figcaption class='wp-caption-text gallery-caption' id='gallery-1-99921'>\n\t\t\t\t<a class=\"click__begin\">Click Here to Begin Slideshow<\/a>\n\nIn the hypothetical world, a fan wouldn&#8217;t be required if your car was constantly driven at high speeds (definitely an interesting concept, but not too practical).\u00a0 Airflow from the vehicle&#8217;s velocity would be sufficient to allow for adequate air movement through the radiator surface, with the result being proper cooling. While this would be an ideal situation, it&#8217;s seldom possible.\u00a0 Or realistic.\u00a0 Because of this, a fan of some sort becomes a necessity.\u00a0\n\nWhile electric fans are by far the most common today (here, an electric motor simply turns the fan on or off, depending upon a pre-determined temperature), many vehicles on the road today \u2013 particularly vintage examples &#8212; still rely upon mechanical fans.\n\nThere have been a number of mechanical engine-driven fan types used on passenger cars over the years \u2013 some fixed, some \u201cflexible\u201d.\u00a0 \u00a0\u00a0A fixed fan rotates constantly with the water pump shaft.\u00a0 On the other hand, a common thermal clutch fan operates by way of a viscous coupling. The fan clutch is a small fluid coupling bolted to the fan just behind the radiator. It incorporates a thermostatic device that controls the fan speed. This ensures that the fan will rotate at a speed that is sufficient to maintain engine cooling. Simultaneously, the thermostatic devise can disengage the fan when it is no longer needed (engine is cooled).\n\nSo how does it work?\u00a0 The key is the clutch.\u00a0 It is engineered with a fluid coupling partially filled with a silicone-based fluid designed for just this purpose. Within the clutch, you\u2019ll find several passages (cavities), separated with a valve of sorts.\u00a0 On the nose of the clutch, you\u2019ll find either a coiled bimetal spring or a flat bimetal strip.\u00a0 As the temperature of the air passing over the radiator rises, the bimetal spring simply expands (actually, the coils unwind).\u00a0 In the case of the bimetal strip, it bends in or out depending upon the temperature.\u00a0 As the coils in the spring unwind (or in the case of a strip, bends or flexes), more silicone fluid is allowed to enter the fluid coupling.\u00a0 With more silicone fluid in place, the slip within the clutch is reduced.\u00a0 That means the fan is allowed to slowly rotate.\u00a0 As the temperature continues to rise, the coil will fully unwind (expand).\u00a0 Eventually, the clutch on the nose of the fan will become almost completely locked, which in turn allows the fan to draw the maximum amount of air through the radiator.\u00a0 As the air passing through the radiator cools (for example, driving at uninterrupted highway speeds), then the fan coupling decreases.\u00a0 Eventually, the fan slows and freewheels.\u00a0 This reduces noise, saves engine power and of course, improves fuel economy. Most fan clutches allow the fluid to drain into the [fluid] cavity when the engine is shut down.\u00a0 As a result, the clutch (and the fan) becomes engaged.\u00a0 When you start an engine, even from cold, it will take a minute or two for the clutch to slow down (hence the extra noise when the vehicle is first started \u2013 the fan is locked \u201con\u201d). It\u2019s not hard to see that the fan clutch is a simple but actually brilliant device.\n\nSimple flex fans have been in use for a long period of time too.\u00a0 They reduce their pitch as engine RPM increases (or more correctly, as pulley speed increases).\u00a0 These are even simpler devices than clutch fans. Here, the blades (stainless steel, aluminum, fiberglass or sometimes composites) rely upon centrifugal force to perform the work. As pointed out above, the pitch of the respective blades flatten as the engine speed increases. At low engine speed, the fan draws the maximum amount of air through the radiator as possible, but as the engine increases (and theoretically, the vehicle speed increases), the fan flattens.\u00a0 This draws in little air and consumes less power to turn.\u00a0 The flex fan is an extremely simple device.\u00a0 More in the accompanying photos:\n\n<a class=\"click__begin\">Click Here to Begin Slideshow<\/a>\n\t\t\t\t<\/figcaption><\/figure><figure class='gallery-item'>\n\t\t\t<div class='gallery-icon landscape'>\n\t\t\t\t<a href='https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-2-min\/'><img loading=\"lazy\" decoding=\"async\" width=\"150\" height=\"150\" src=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-2-min-150x150.jpg\" class=\"attachment-thumbnail size-thumbnail\" alt=\"Mechanically Speaking: How Clutch &amp; Flex Fans Work\" aria-describedby=\"gallery-1-99922\" data-attachment-id=\"99922\" data-permalink=\"https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-2-min\/\" data-orig-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-2-min.jpg\" data-orig-size=\"1000,659\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"Mechanically Speaking: How Clutch &amp;#038; Flex Fans Work\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;The actual fan used in conjunction with most clutch setups doesn\u2019t look much different than any other fan.  Essentially, it\u2019s sandwiched between the water pump and the fan clutch, however the fan not hooked up directly to the water pump pulley (the fan clutch is). &lt;\/p&gt;\n\" data-medium-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-2-min-300x198.jpg\" data-large-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-2-min.jpg\" \/><\/a>\n\t\t\t<\/div>\n\t\t\t\t<figcaption class='wp-caption-text gallery-caption' id='gallery-1-99922'>\n\t\t\t\tThe actual fan used in conjunction with most clutch setups doesn\u2019t look much different than any other fan.  Essentially, it\u2019s sandwiched between the water pump and the fan clutch, however the fan not hooked up directly to the water pump pulley (the fan clutch is). \n\t\t\t\t<\/figcaption><\/figure><figure class='gallery-item'>\n\t\t\t<div class='gallery-icon landscape'>\n\t\t\t\t<a href='https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-3-min\/'><img loading=\"lazy\" decoding=\"async\" width=\"150\" height=\"150\" src=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-3-min-150x150.jpg\" class=\"attachment-thumbnail size-thumbnail\" alt=\"Mechanically Speaking: How Clutch &amp; Flex Fans Work\" aria-describedby=\"gallery-1-99923\" data-attachment-id=\"99923\" data-permalink=\"https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-3-min\/\" data-orig-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-3-min.jpg\" data-orig-size=\"1000,669\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"Mechanically Speaking: How Clutch &amp;#038; Flex Fans Work\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Here\u2019s a look at a common replacement fan clutch.  Behind the gold colored face is a series of cavities separated by a valve device.  A special silicone fluid is used to make the coupling inside the clutch.  The fan clutch is positioned directly behind the radiator.&lt;\/p&gt;\n\" data-medium-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-3-min-300x201.jpg\" data-large-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-3-min.jpg\" \/><\/a>\n\t\t\t<\/div>\n\t\t\t\t<figcaption class='wp-caption-text gallery-caption' id='gallery-1-99923'>\n\t\t\t\tHere\u2019s a look at a common replacement fan clutch.  Behind the gold colored face is a series of cavities separated by a valve device.  A special silicone fluid is used to make the coupling inside the clutch.  The fan clutch is positioned directly behind the radiator.\n\t\t\t\t<\/figcaption><\/figure><figure class='gallery-item'>\n\t\t\t<div class='gallery-icon landscape'>\n\t\t\t\t<a href='https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-4-min\/'><img loading=\"lazy\" decoding=\"async\" width=\"150\" height=\"150\" src=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-4-min-150x150.jpg\" class=\"attachment-thumbnail size-thumbnail\" alt=\"Mechanically Speaking: How Clutch &amp; Flex Fans Work\" aria-describedby=\"gallery-1-99924\" data-attachment-id=\"99924\" data-permalink=\"https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-4-min\/\" data-orig-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-4-min.jpg\" data-orig-size=\"1000,669\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"Mechanically Speaking: How Clutch &amp;#038; Flex Fans Work\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;The pointer shows the coiled bi-metal spring fitted to this particular fan clutch.  As the temperature increases, the spring \u201cuncoils\u201d, which in turn allows the silicone coupling fluid to move within the clutch.  The text offers more information.&lt;\/p&gt;\n\" data-medium-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-4-min-300x201.jpg\" data-large-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-4-min.jpg\" \/><\/a>\n\t\t\t<\/div>\n\t\t\t\t<figcaption class='wp-caption-text gallery-caption' id='gallery-1-99924'>\n\t\t\t\tThe pointer shows the coiled bi-metal spring fitted to this particular fan clutch.  As the temperature increases, the spring \u201cuncoils\u201d, which in turn allows the silicone coupling fluid to move within the clutch.  The text offers more information.\n\t\t\t\t<\/figcaption><\/figure><figure class='gallery-item'>\n\t\t\t<div class='gallery-icon landscape'>\n\t\t\t\t<a href='https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-5-min\/'><img loading=\"lazy\" decoding=\"async\" width=\"150\" height=\"150\" src=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-5-min-150x150.jpg\" class=\"attachment-thumbnail size-thumbnail\" alt=\"Mechanically Speaking: How Clutch &amp; Flex Fans Work\" aria-describedby=\"gallery-1-99925\" data-attachment-id=\"99925\" data-permalink=\"https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-5-min\/\" data-orig-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-5-min.jpg\" data-orig-size=\"1000,702\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"Mechanically Speaking: How Clutch &amp;#038; Flex Fans Work\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Flex fans are even simpler devices than clutch fans. Here, the fan is a one-piece assembly engineered with a series of blades that can physically flatten (more in the next image).  This example is manufactured from stainless steel, however you can come across flex fans manufactured from aluminum, fiberglass and composite materials. &lt;\/p&gt;\n\" data-medium-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-5-min-300x211.jpg\" data-large-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-5-min.jpg\" \/><\/a>\n\t\t\t<\/div>\n\t\t\t\t<figcaption class='wp-caption-text gallery-caption' id='gallery-1-99925'>\n\t\t\t\tFlex fans are even simpler devices than clutch fans. Here, the fan is a one-piece assembly engineered with a series of blades that can physically flatten (more in the next image).  This example is manufactured from stainless steel, however you can come across flex fans manufactured from aluminum, fiberglass and composite materials. \n\t\t\t\t<\/figcaption><\/figure><figure class='gallery-item'>\n\t\t\t<div class='gallery-icon landscape'>\n\t\t\t\t<a href='https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-6-min\/'><img loading=\"lazy\" decoding=\"async\" width=\"150\" height=\"150\" src=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-6-min-150x150.jpg\" class=\"attachment-thumbnail size-thumbnail\" alt=\"Mechanically Speaking: How Clutch &amp; Flex Fans Work\" aria-describedby=\"gallery-1-99920\" data-attachment-id=\"99920\" data-permalink=\"https:\/\/www.racingjunk.com\/news\/mechanically-speaking-how-clutch-flex-fans-work\/fan-6-min\/\" data-orig-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-6-min.jpg\" data-orig-size=\"1000,669\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"Mechanically Speaking: How Clutch &amp;#038; Flex Fans Work\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;In a flex fan application, the fan blade (shown here) physically flattens due to centrifugal force. As the engine speed increases, the blade is allowed to flatten, which in turn, frees horsepower in the engine and improves fuel economy.  As the engine speed slows, then the blade returns to the normal pitch, effectively drawing more air through the radiator when it is most needed.&lt;\/p&gt;\n\" data-medium-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-6-min-300x201.jpg\" data-large-file=\"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-6-min.jpg\" \/><\/a>\n\t\t\t<\/div>\n\t\t\t\t<figcaption class='wp-caption-text gallery-caption' id='gallery-1-99920'>\n\t\t\t\tIn a flex fan application, the fan blade (shown here) physically flattens due to centrifugal force. As the engine speed increases, the blade is allowed to flatten, which in turn, frees horsepower in the engine and improves fuel economy.  As the engine speed slows, then the blade returns to the normal pitch, effectively drawing more air through the radiator when it is most needed.\n\t\t\t\t<\/figcaption><\/figure>\n\t\t<\/div>\n\n","protected":false},"excerpt":{"rendered":"<div class=\"mh-excerpt\"><p>In the hypothetical world, a fan wouldn&#8217;t be required if your car was constantly driven at high speeds (definitely an interesting concept, but not too practical).\u00a0<\/p>\n<\/div>","protected":false},"author":20,"featured_media":99921,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[5013,3697,5008,11,3470,4879],"tags":[11565,11553,11561,11568,11556,11566,11570,11560,11569,11549,11559,11546,11547,11567,11555,11558,11562,11557,11548,11550,11563,11554,11551,11552,11564],"class_list":["post-99919","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-electronics-wiring","category-galleries","category-engine","category-how-tos","category-news","category-slideshow","tag-automotive-fans","tag-bimetal-spring","tag-classic-car-cooling","tag-clutch-fan-function","tag-cooling-efficiency","tag-cooling-fan-mechanics","tag-cooling-fan-technology","tag-cooling-system","tag-electric-fan-vs-mechanical-fan","tag-engine-cooling","tag-engine-temperature-control","tag-fan-clutch","tag-flex-fan","tag-flex-fan-blades","tag-flex-fan-operation","tag-fuel-economy","tag-high-performance-cooling","tag-horsepower-savings","tag-mechanical-fans","tag-radiator-airflow","tag-radiator-fan","tag-silicone-fluid","tag-thermal-clutch-fan","tag-viscous-coupling","tag-water-pump-pulley"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2025\/02\/Fan-1-min-e1739557187872.jpg","jetpack_shortlink":"https:\/\/wp.me\/p42YSK-pZB","jetpack_sharing_enabled":true,"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/99919","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/comments?post=99919"}],"version-history":[{"count":1,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/99919\/revisions"}],"predecessor-version":[{"id":99926,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/99919\/revisions\/99926"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/media\/99921"}],"wp:attachment":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/media?parent=99919"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/categories?post=99919"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/tags?post=99919"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}