{"id":235,"date":"2025-10-31T00:25:51","date_gmt":"2025-10-31T00:25:51","guid":{"rendered":"https:\/\/vibromera.eu\/glossary\/shaft-whip\/"},"modified":"2026-07-03T10:10:47","modified_gmt":"2026-07-03T10:10:47","slug":"shaft-whip","status":"publish","type":"glossary","link":"https:\/\/vibromera.eu\/ga\/glossary\/shaft-whip\/","title":{"rendered":"What is Shaft Whip? Severe Rotor Instability Explained"},"content":{"rendered":"<h1>Understanding Shaft Whip in Rotating Machinery<\/h1>\n\t\t<section class=\"woocommerce hestia-shop products is-shortcode\" id=\"products\" data-sorder=\"hestia_shop\" >\n\t\t\t\t\t\t<div class=\"\">\n\t\t\t\t\t\t<div class=\"hestia-shop-content\">\n\t\t\t<div class=\"row\" data-aos=\"fade-up\" >\t\t\t\t\t<div class=\"col-ms-6 col-sm-6 col-md-3 shop-item\">\n\t\t\t\t\t\t<a href=\"https:\/\/vibromera.eu\/ga\/product\/balanset-1\/\" class=\"woocommerce-LoopProduct-link woocommerce-loop-product__link\">\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"card-image\">\n\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/vibromera.eu\/ga\/product\/balanset-1\/\" title=\"Portable balancer &#038; Vibration analyzer Balanset-1A\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"230\" height=\"153\" src=\"https:\/\/vibromera.eu\/wp-content\/uploads\/2023\/09\/77-e1693745667801-230x153.webp\" class=\"attachment-woocommerce_thumbnail size-woocommerce_thumbnail\" alt=\"Balanset-1A full kit portable balancer and vibration analyzer\" srcset=\"https:\/\/vibromera.eu\/wp-content\/uploads\/2023\/09\/77-e1693745667801-230x153.webp 230w, https:\/\/vibromera.eu\/wp-content\/uploads\/2023\/09\/77-e1693745667801-18x12.webp 18w, https:\/\/vibromera.eu\/wp-content\/uploads\/2023\/09\/77-e1693745667801-360x240.webp 360w, https:\/\/vibromera.eu\/wp-content\/uploads\/2023\/09\/77-e1693745667801-272x182.webp 272w\" sizes=\"auto, (max-width: 230px) 100vw, 230px\" \/>\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<div class=\"ripple-container\"><\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"content\">\n\t\t\t\t\t\t\t\t<span class=\"category\"><a href=\"https:\/\/vibromera.eu\/ga\/product-category\/devices\/\" rel=\"tag\">Devices<\/a><\/span>\n\t\t\t\t\t\t\t\t<h4 class=\"card-title\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<a class=\"shop-item-title-link\" href=\"https:\/\/vibromera.eu\/ga\/product\/balanset-1\/\" title=\"Portable balancer &#038; Vibration analyzer Balanset-1A\">Portable balancer &#038; Vibration analyzer Balanset-1A<\/a>\n\n\t\t\t\t\t\t\t\t<\/h4>\n\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t<div class=\"footer\">\n\n\t\t\t\t\t\t\t\t\t<div class=\"price\"><h4><span class=\"woocommerce-Price-amount amount\"><span class=\"woocommerce-Price-currencySymbol\">&euro;<\/span>1,975.00<\/span> + VAT (if applicable)<\/h4><\/div>\n\t\t\t\t\t\t\t\t\t<div class=\"stats\">\n\t\t\t\t\t\t\t\t\t\t<a rel=\"nofollow\" href=\"\/ga\/wp-json\/wp\/v2\/glossary\/235?add-to-cart=986\" data-quantity=\"1\" data-product_id=\"986\" data-product_sku=\"BS-1\" class=\"button product_type_simple add_to_cart_button ajax_add_to_cart btn btn-just-icon btn-simple btn-default\" title=\"Add to cart\" data-no-translation-title=\"\"><i rel=\"tooltip\" data-original-title=\"Add to cart\" class=\"fas fa-cart-plus\" data-no-translation-data-original-title=\"\"><\/i><\/a>\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/a><a href=\"\/ga\/wp-json\/wp\/v2\/glossary\/235?add-to-cart=986\" aria-describedby=\"woocommerce_loop_add_to_cart_link_describedby_986\" data-quantity=\"1\" class=\"button product_type_simple add_to_cart_button ajax_add_to_cart\" data-product_id=\"986\" data-product_sku=\"BS-1\" aria-label=\"Add to cart: \u201cPortable balancer &amp; Vibration analyzer Balanset-1A\u201d\" rel=\"nofollow\" data-success_message=\"\u201cPortable balancer &amp; Vibration analyzer Balanset-1A\u201d has been added to your cart\" data-no-translation=\"\" data-trp-gettext=\"\" data-no-translation-aria-label=\"\" data-no-translation-data-success_message=\"\">Add to cart<\/a>\t<span id=\"woocommerce_loop_add_to_cart_link_describedby_986\" class=\"screen-reader-text\">\n\t\t\t<\/span>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t<div class=\"col-ms-6 col-sm-6 col-md-3 shop-item\">\n\t\t\t\t\t\t<a href=\"https:\/\/vibromera.eu\/ga\/product\/vibration-sensor\/\" class=\"woocommerce-LoopProduct-link woocommerce-loop-product__link\">\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"card-image\">\n\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/vibromera.eu\/ga\/product\/vibration-sensor\/\" title=\"Vibration sensor\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"230\" height=\"153\" src=\"https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-3-230x153.webp\" class=\"attachment-woocommerce_thumbnail size-woocommerce_thumbnail\" alt=\"Balanset-1A vibration sensor close-up\" srcset=\"https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-3-230x153.webp 230w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-3-600x400.webp 600w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-3-300x200.webp 300w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-3-768x512.webp 768w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-3-1024x682.webp 1024w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-3-272x182.webp 272w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-3.webp 1280w\" sizes=\"auto, (max-width: 230px) 100vw, 230px\" \/>\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<div class=\"ripple-container\"><\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"content\">\n\t\t\t\t\t\t\t\t<span class=\"category\"><a href=\"https:\/\/vibromera.eu\/ga\/product-category\/parts\/\" rel=\"tag\">Parts<\/a><\/span>\n\t\t\t\t\t\t\t\t<h4 class=\"card-title\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<a class=\"shop-item-title-link\" href=\"https:\/\/vibromera.eu\/ga\/product\/vibration-sensor\/\" title=\"Vibration sensor\">Vibration sensor<\/a>\n\n\t\t\t\t\t\t\t\t<\/h4>\n\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t<div class=\"footer\">\n\n\t\t\t\t\t\t\t\t\t<div class=\"price\"><h4><span class=\"woocommerce-Price-amount amount\"><span class=\"woocommerce-Price-currencySymbol\">&euro;<\/span>90.00<\/span> + VAT (if applicable)<\/h4><\/div>\n\t\t\t\t\t\t\t\t\t<div class=\"stats\">\n\t\t\t\t\t\t\t\t\t\t<a rel=\"nofollow\" href=\"\/ga\/wp-json\/wp\/v2\/glossary\/235?add-to-cart=1820\" data-quantity=\"1\" data-product_id=\"1820\" data-product_sku=\"VS-1\" class=\"button product_type_simple add_to_cart_button ajax_add_to_cart btn btn-just-icon btn-simple btn-default\" title=\"Add to cart\" data-no-translation-title=\"\"><i rel=\"tooltip\" data-original-title=\"Add to cart\" class=\"fas fa-cart-plus\" data-no-translation-data-original-title=\"\"><\/i><\/a>\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/a><a href=\"\/ga\/wp-json\/wp\/v2\/glossary\/235?add-to-cart=1820\" aria-describedby=\"woocommerce_loop_add_to_cart_link_describedby_1820\" data-quantity=\"1\" class=\"button product_type_simple add_to_cart_button ajax_add_to_cart\" data-product_id=\"1820\" data-product_sku=\"VS-1\" aria-label=\"Add to cart: \u201cVibration sensor\u201d\" rel=\"nofollow\" data-success_message=\"\u201cVibration sensor\u201d has been added to your cart\" data-no-translation=\"\" data-trp-gettext=\"\" data-no-translation-aria-label=\"\" data-no-translation-data-success_message=\"\">Add to cart<\/a>\t<span id=\"woocommerce_loop_add_to_cart_link_describedby_1820\" class=\"screen-reader-text\">\n\t\t\t<\/span>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t<div class=\"col-ms-6 col-sm-6 col-md-3 shop-item\">\n\t\t\t\t\t\t<a href=\"https:\/\/vibromera.eu\/ga\/product\/optical-sensor-for-balanset-and-arbalance\/\" class=\"woocommerce-LoopProduct-link woocommerce-loop-product__link\">\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"card-image\">\n\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/vibromera.eu\/ga\/product\/optical-sensor-for-balanset-and-arbalance\/\" title=\"Optical Sensor (Laser Tachometer)\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"230\" height=\"153\" src=\"https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU-230x153.webp\" class=\"attachment-woocommerce_thumbnail size-woocommerce_thumbnail\" alt=\"Optical Sensor (Laser Tachometer)\" srcset=\"https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU-230x153.webp 230w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU-300x200.webp 300w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU-1024x682.webp 1024w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU-768x512.webp 768w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU-1536x1023.webp 1536w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU-18x12.webp 18w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU-360x240.webp 360w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU-460x306.webp 460w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU-600x400.webp 600w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU-272x182.webp 272w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/ZKqzGXSCCBU.webp 1600w\" sizes=\"auto, (max-width: 230px) 100vw, 230px\" \/>\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<div class=\"ripple-container\"><\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"content\">\n\t\t\t\t\t\t\t\t<span class=\"category\"><a href=\"https:\/\/vibromera.eu\/ga\/product-category\/parts\/\" rel=\"tag\">Parts<\/a><\/span>\n\t\t\t\t\t\t\t\t<h4 class=\"card-title\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<a class=\"shop-item-title-link\" href=\"https:\/\/vibromera.eu\/ga\/product\/optical-sensor-for-balanset-and-arbalance\/\" title=\"Optical Sensor (Laser Tachometer)\">Optical Sensor (Laser Tachometer)<\/a>\n\n\t\t\t\t\t\t\t\t<\/h4>\n\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t<div class=\"footer\">\n\n\t\t\t\t\t\t\t\t\t<div class=\"price\"><h4><span class=\"woocommerce-Price-amount amount\"><span class=\"woocommerce-Price-currencySymbol\">&euro;<\/span>124.00<\/span> + VAT (if applicable)<\/h4><\/div>\n\t\t\t\t\t\t\t\t\t<div class=\"stats\">\n\t\t\t\t\t\t\t\t\t\t<a rel=\"nofollow\" href=\"\/ga\/wp-json\/wp\/v2\/glossary\/235?add-to-cart=1832\" data-quantity=\"1\" data-product_id=\"1832\" data-product_sku=\"Tach-1\" class=\"button product_type_simple add_to_cart_button ajax_add_to_cart btn btn-just-icon btn-simple btn-default\" title=\"Add to cart\" data-no-translation-title=\"\"><i rel=\"tooltip\" data-original-title=\"Add to cart\" class=\"fas fa-cart-plus\" data-no-translation-data-original-title=\"\"><\/i><\/a>\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/a><a href=\"\/ga\/wp-json\/wp\/v2\/glossary\/235?add-to-cart=1832\" aria-describedby=\"woocommerce_loop_add_to_cart_link_describedby_1832\" data-quantity=\"1\" class=\"button product_type_simple add_to_cart_button ajax_add_to_cart\" data-product_id=\"1832\" data-product_sku=\"Tach-1\" aria-label=\"Add to cart: \u201cOptical Sensor (Laser Tachometer)\u201d\" rel=\"nofollow\" data-success_message=\"\u201cOptical Sensor (Laser Tachometer)\u201d has been added to your cart\" data-no-translation=\"\" data-trp-gettext=\"\" data-no-translation-aria-label=\"\" data-no-translation-data-success_message=\"\">Add to cart<\/a>\t<span id=\"woocommerce_loop_add_to_cart_link_describedby_1832\" class=\"screen-reader-text\">\n\t\t\t<\/span>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t<div class=\"col-ms-6 col-sm-6 col-md-3 shop-item\">\n\t\t\t\t\t\t<a href=\"https:\/\/vibromera.eu\/ga\/product\/balanset-4\/\" class=\"woocommerce-LoopProduct-link woocommerce-loop-product__link\">\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"card-image\">\n\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/vibromera.eu\/ga\/product\/balanset-4\/\" title=\"Balanset-4\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"230\" height=\"153\" src=\"https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/balkom4-230x153.webp\" class=\"attachment-woocommerce_thumbnail size-woocommerce_thumbnail\" alt=\"Vibromera rotor balancing kit: carry case, multi-channel signal conditioner, handheld analyzer, magnetic base, vibration sensors, and coiled cables.\" srcset=\"https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/balkom4-230x153.webp 230w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/balkom4-300x200.webp 300w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/balkom4-18x12.webp 18w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/balkom4-360x240.webp 360w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/balkom4-460x306.webp 460w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/balkom4-600x400.webp 600w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/balkom4-272x182.webp 272w, https:\/\/vibromera.eu\/wp-content\/uploads\/2022\/12\/balkom4.webp 640w\" sizes=\"auto, (max-width: 230px) 100vw, 230px\" \/>\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<div class=\"ripple-container\"><\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"content\">\n\t\t\t\t\t\t\t\t<span class=\"category\"><a href=\"https:\/\/vibromera.eu\/ga\/product-category\/devices\/\" rel=\"tag\">Devices<\/a><\/span>\n\t\t\t\t\t\t\t\t<h4 class=\"card-title\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<a class=\"shop-item-title-link\" href=\"https:\/\/vibromera.eu\/ga\/product\/balanset-4\/\" title=\"Balanset-4\">Balanset-4<\/a>\n\n\t\t\t\t\t\t\t\t<\/h4>\n\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t<div class=\"footer\">\n\n\t\t\t\t\t\t\t\t\t<div class=\"price\"><h4><span class=\"woocommerce-Price-amount amount\"><span class=\"woocommerce-Price-currencySymbol\">&euro;<\/span>6,803.00<\/span> + VAT (if applicable)<\/h4><\/div>\n\t\t\t\t\t\t\t\t\t<div class=\"stats\">\n\t\t\t\t\t\t\t\t\t\t<a rel=\"nofollow\" href=\"\/ga\/wp-json\/wp\/v2\/glossary\/235?add-to-cart=1833\" data-quantity=\"1\" data-product_id=\"1833\" data-product_sku=\"BS-4\" class=\"button product_type_simple add_to_cart_button ajax_add_to_cart btn btn-just-icon btn-simple btn-default\" title=\"Add to cart\" data-no-translation-title=\"\"><i rel=\"tooltip\" data-original-title=\"Add to cart\" class=\"fas fa-cart-plus\" data-no-translation-data-original-title=\"\"><\/i><\/a>\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/a><a href=\"\/ga\/wp-json\/wp\/v2\/glossary\/235?add-to-cart=1833\" aria-describedby=\"woocommerce_loop_add_to_cart_link_describedby_1833\" data-quantity=\"1\" class=\"button product_type_simple add_to_cart_button ajax_add_to_cart\" data-product_id=\"1833\" data-product_sku=\"BS-4\" aria-label=\"Add to cart: \u201cBalanset-4\u201d\" rel=\"nofollow\" data-success_message=\"\u201cBalanset-4\u201d has been added to your cart\" data-no-translation=\"\" data-trp-gettext=\"\" data-no-translation-aria-label=\"\" data-no-translation-data-success_message=\"\">Add to cart<\/a>\t<span id=\"woocommerce_loop_add_to_cart_link_describedby_1833\" class=\"screen-reader-text\">\n\t\t\t<\/span>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div><!-- \/.row --><div class=\"row\">\t\t\t\t\t<div class=\"col-ms-6 col-sm-6 col-md-3 shop-item\">\n\t\t\t\t\t\t<a href=\"https:\/\/vibromera.eu\/ga\/product\/magnet-stand\/\" class=\"woocommerce-LoopProduct-link woocommerce-loop-product__link\">\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"card-image\">\n\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/vibromera.eu\/ga\/product\/magnet-stand\/\" title=\"Magnetic Stand Insize-60-kgf\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"230\" height=\"153\" src=\"https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-36-230x153.webp\" class=\"attachment-woocommerce_thumbnail size-woocommerce_thumbnail\" alt=\"Magnet base.\" srcset=\"https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-36-230x153.webp 230w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-36-600x400.webp 600w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-36-300x200.webp 300w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-36-1024x682.webp 1024w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-36-768x512.webp 768w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-36-360x240.webp 360w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-36-272x182.webp 272w, https:\/\/vibromera.eu\/wp-content\/uploads\/2018\/05\/IMG-36.webp 1280w\" sizes=\"auto, (max-width: 230px) 100vw, 230px\" \/>\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<div class=\"ripple-container\"><\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"content\">\n\t\t\t\t\t\t\t\t<span class=\"category\"><a href=\"https:\/\/vibromera.eu\/ga\/product-category\/parts\/\" rel=\"tag\">Parts<\/a><\/span>\n\t\t\t\t\t\t\t\t<h4 class=\"card-title\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<a 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class=\"screen-reader-text\">\n\t\t\t<\/span>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/section>\n\t\t\n<p><strong>Shaft whip<\/strong> \u2014 known as <em>oil whip<\/em> when it originates in hydrodynamic bearings \u2014 is a severe form of <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/rotor-instability\/\">rotor instability<\/a> marked by violent <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/self-excited-vibration\/\">self-excited vibration<\/a>. It appears when a rotor running in fluid-film bearings exceeds a critical threshold speed, typically around twice the first <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/critical-speed\/\">critical speed<\/a>. Once whip takes hold, the vibration frequency &#8220;locks&#8221; onto the rotor&#8217;s first <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/natural-frequency\/\">natural frequency<\/a> and stays there regardless of any further speed increase, with amplitude limited only by bearing clearance \u2014 or by catastrophic failure. It is one of the most dangerous conditions in high-speed machinery because it develops suddenly, grows to destructive levels within seconds, and cannot be cured by <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/balancing\/\">balancing<\/a> or any other conventional correction. It demands immediate shutdown followed by changes to the bearing system to prevent recurrence.<\/p>\n<h2>1. The Progression: From Oil Whirl to Shaft Whip<\/h2>\n<p>Whip rarely arrives without warning \u2014 it is the end point of a four-stage progression that an attentive analyst can intercept long before the destructive stage.<\/p>\n<h3>Stage 1 \u2014 Stable Operation<\/h3>\n<ul>\n<li>The rotor runs below the instability threshold.<\/li>\n<li>Only normal <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/forced-vibration\/\">forced vibration<\/a> from <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/unbalance\/\">unbalance<\/a> is present.<\/li>\n<li>The bearing oil film provides stable, well-damped support.<\/li>\n<\/ul>\n<h3>Stage 2 \u2014 Oil Whirl Onset<\/h3>\n<p>As speed climbs past roughly 2\u00d7 the first critical speed, <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/oil-whirl\/\">oil whirl<\/a> begins:<\/p>\n<ul>\n<li>A <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/sub-synchronous\/\">sub-synchronous<\/a> vibration appears at about 0.43\u20130.48\u00d7 shaft speed.<\/li>\n<li>Amplitude is initially moderate and speed-dependent.<\/li>\n<li>The whirl frequency rises proportionally with shaft speed.<\/li>\n<li>It may be intermittent or continuous.<\/li>\n<li>It can coexist with the normal 1\u00d7 vibration from unbalance.<\/li>\n<\/ul>\n<h3>Stage 3 \u2014 The Whip Transition<\/h3>\n<p>When the rising oil-whirl frequency climbs far enough to match the first natural frequency, the behaviour changes character abruptly:<\/p>\n<ul>\n<li><strong>Frequency lock-in:<\/strong> the vibration frequency stops tracking speed and pins itself to the natural frequency.<\/li>\n<li><strong>Resonant amplification:<\/strong> amplitude grows dramatically because the system is now in <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/resonance\/\">resonance<\/a>.<\/li>\n<li><strong>Sudden onset:<\/strong> the jump from whirl to whip can be effectively instantaneous.<\/li>\n<li><strong>Speed independence:<\/strong> further speed increases no longer change the frequency \u2014 only the amplitude.<\/li>\n<\/ul>\n<h3>Stage 4 \u2014 Shaft Whip (Critical Condition)<\/h3>\n<ul>\n<li>Vibration sits at a constant frequency \u2014 the first natural frequency, typically 40\u201360 Hz.<\/li>\n<li>Amplitude reaches 5\u201320 times the normal unbalance vibration.<\/li>\n<li>The shaft may strike its bearing-clearance limits.<\/li>\n<li>Bearings and oil heat rapidly.<\/li>\n<li>Catastrophic failure can follow within minutes if the machine is not stopped.<\/li>\n<\/ul>\n<h2>2. The Physical Mechanism<\/h2>\n<p>Whip is driven by the fluid dynamics of the bearing oil film itself, which is why it cannot be balanced away \u2014 the destabilising energy comes from the lubricant, not from a heavy spot. The sequence runs as follows:<\/p>\n<ol>\n<li><strong>Oil-wedge formation:<\/strong> the rotating shaft drags lubricant around the bearing, building a pressurised wedge.<\/li>\n<li><strong>Tangential force:<\/strong> that wedge pushes on the journal in a direction perpendicular to the radial offset \u2014 a cross-coupled, tangential force.<\/li>\n<li><strong>Orbit motion:<\/strong> the tangential force drives the shaft centre to <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/whirl\/\">whirl<\/a> in an <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/orbit\/\">orbit<\/a> at roughly half shaft speed.<\/li>\n<li><strong>Energy extraction:<\/strong> the orbiting motion draws energy out of the shaft&#8217;s rotation to sustain itself \u2014 the hallmark of a self-excited vibration.<\/li>\n<li><strong>Resonance lock:<\/strong> when the orbit frequency coincides with the natural frequency, resonance amplifies the motion.<\/li>\n<li><strong>Limit cycle:<\/strong> amplitude grows until it is bounded by bearing clearance or by failure.<\/li>\n<\/ol>\n<p>Because the exciting force scales with the lubricant&#8217;s behaviour, anything that raises the oil-film stiffness or the system <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/damping\/\">damping<\/a> raises the speed at which instability begins.<\/p>\n<h2>3. Diagnostic Identification<\/h2>\n<p>Shaft whip leaves an unmistakable fingerprint in vibration data, which makes early recognition possible if the right plots are reviewed.<\/p>\n<h3>Vibration Signature<\/h3>\n<ul>\n<li><strong><a href=\"https:\/\/vibromera.eu\/ga\/glossary\/spectrum\/\">Spectrum<\/a>:<\/strong> a large peak at the sub-synchronous (first natural) frequency that stays put regardless of speed changes.<\/li>\n<li><strong><a href=\"https:\/\/vibromera.eu\/ga\/glossary\/waterfall-plot\/\">Waterfall plot<\/a>:<\/strong> the sub-synchronous component shows up as a vertical line (constant frequency) rather than the diagonal line of a speed-proportional component.<\/li>\n<li><strong><a href=\"https:\/\/vibromera.eu\/ga\/glossary\/order-analysis\/\">Order analysis<\/a>:<\/strong> a fractional order that <em>decreases<\/em> as speed rises \u2014 for example drifting from 0.5\u00d7 to 0.4\u00d7 to 0.35\u00d7 \u2014 because the frequency is fixed while speed climbs.<\/li>\n<li><strong>Orbit:<\/strong> a large circular or elliptical orbit at the natural frequency.<\/li>\n<\/ul>\n<p>A <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/bode-plot\/\">Bode plot<\/a> taken on <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/coastdown\/\">coastdown<\/a> further separates a true resonance from a whip, since the locked sub-synchronous line behaves quite differently from the synchronous critical-speed peak.<\/p>\n<h3>Onset Speed<\/h3>\n<ul>\n<li><strong>Typical threshold:<\/strong> 2.0\u20132.5\u00d7 the first critical speed.<\/li>\n<li><strong>Bearing-dependent:<\/strong> the exact threshold varies with bearing design, <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/preload\/\">preload<\/a>, and oil viscosity.<\/li>\n<li><strong>Sudden onset:<\/strong> a small speed increase can trip the rotor from stable to fully unstable.<\/li>\n<\/ul>\n<h2>4. Prevention Strategies<\/h2>\n<p>Because whip cannot be balanced out, prevention focuses on the <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/journal-bearing\/\">journal bearing<\/a> and on how the machine is operated.<\/p>\n<h3>Bearing Design Modifications<\/h3>\n<p><strong>1. Tilting-pad bearings<\/strong> \u2014 the most effective fix. The pads pivot independently, eliminating the destabilising cross-coupling force; they are inherently stable across a wide speed range and are the industry standard for high-speed turbomachinery.<\/p>\n<p><strong>2. Pressure-dam bearings<\/strong> \u2014 a modified cylindrical bearing with a groove or dam that raises effective damping and stiffness; cheaper than tilting-pad but less effective.<\/p>\n<p><strong>3. Bearing preload<\/strong> \u2014 applying radial preload (often through an offset-bore design) raises stiffness and pushes the instability threshold higher.<\/p>\n<p><strong>4. <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/squeeze-film-damper\/\">Squeeze-film dampers<\/a><\/strong> \u2014 an external damping element surrounding the bearing that adds damping without redesigning the bearing itself, well suited to retrofits.<\/p>\n<h3>Operational Measures<\/h3>\n<ul>\n<li><strong>Speed limitation:<\/strong> hold maximum speed below the threshold \u2014 typically under 1.8\u00d7 the first critical.<\/li>\n<li><strong>Load management:<\/strong> run at higher bearing loads where possible, since load increases damping.<\/li>\n<li><strong>Oil-temperature control:<\/strong> a cooler oil is more viscous and more stabilising.<\/li>\n<li><strong>Monitoring:<\/strong> continuous <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/vibration-monitoring\/\">vibration monitoring<\/a> with alarms specifically watching the sub-synchronous band.<\/li>\n<\/ul>\n<h2>5. Consequences and Damage<\/h2>\n<h3>Immediate Effects<\/h3>\n<ul>\n<li><strong>Violent vibration:<\/strong> amplitudes can reach several millimetres (hundreds of mils).<\/li>\n<li><strong>Noise:<\/strong> a loud, distinctive sound quite unlike normal operation.<\/li>\n<li><strong>Rapid bearing heating:<\/strong> temperatures can climb 20\u201350 \u00b0C in minutes.<\/li>\n<li><strong>Oil degradation:<\/strong> high temperature and intense shearing break down the lubricant.<\/li>\n<\/ul>\n<h3>Potential Failures<\/h3>\n<ul>\n<li><strong>Bearing wipe:<\/strong> the babbitt lining melts and is wiped away.<\/li>\n<li><strong>Shaft damage:<\/strong> scoring, galling, or permanent bending.<\/li>\n<li><strong><a href=\"https:\/\/vibromera.eu\/ga\/glossary\/seal-defects\/\">Seal failure<\/a>:<\/strong> excessive shaft motion destroys seals.<\/li>\n<li><strong>Shaft breakage:<\/strong> high-cycle <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/fatigue\/\">fatigue<\/a> from the violent oscillation.<\/li>\n<li><strong><a href=\"https:\/\/vibromera.eu\/ga\/glossary\/coupling-defects\/\">Coupling damage<\/a>:<\/strong> the transmitted forces wreck couplings.<\/li>\n<\/ul>\n<h2>6. Related Phenomena<\/h2>\n<h3>Oil Whirl<\/h3>\n<p><a href=\"https:\/\/vibromera.eu\/ga\/glossary\/oil-whirl\/\">Oil whirl<\/a> is the precursor to whip: the same mechanism, but the frequency has not yet locked onto the natural frequency. Its amplitude is lower, its frequency tracks speed at ~0.43\u20130.48\u00d7, and in some applications it is tolerable.<\/p>\n<h3>Steam Whirl<\/h3>\n<p><a href=\"https:\/\/vibromera.eu\/ga\/glossary\/steam-whirl\/\">Steam whirl<\/a> is a similar instability in steam turbines, driven by aerodynamic forces in labyrinth seals rather than the bearing oil film. It shows the same sub-synchronous vibration locking onto a natural frequency.<\/p>\n<h3>Dry-Friction Whip<\/h3>\n<p>This variant arises at seal locations or from <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/rotor-rub\/\">rotor-stator contact<\/a>. Friction supplies the destabilising mechanism; it is less common than oil whip but equally dangerous and calls for a different remedy \u2014 eliminating the contact or improving the seal.<\/p>\n<h2>7. Case Study: Compressor Shaft Whip<\/h2>\n<p><strong>Scenario:<\/strong> a high-speed centrifugal compressor on plain cylindrical bearings.<\/p>\n<ul>\n<li><strong>Normal operation:<\/strong> 12,000 rpm with vibration of 2.5 mm\/s.<\/li>\n<li><strong>Speed increase:<\/strong> the operator pushed to 13,500 rpm for more capacity.<\/li>\n<li><strong>Onset:<\/strong> at 13,200 rpm a sudden violent vibration developed.<\/li>\n<li><strong>Symptoms:<\/strong> 25 mm\/s at a constant 105 Hz; bearing temperature rose from 70 \u00b0C to 95 \u00b0C in three minutes.<\/li>\n<li><strong>Emergency action:<\/strong> immediate shutdown averted a bearing failure.<\/li>\n<li><strong>Root cause:<\/strong> the first critical speed was 6,300 rpm (105 Hz); at 13,200 rpm the rotor crossed the whip threshold of roughly 2\u00d7 critical \u2248 12,600 rpm, and the vibration locked onto the 105 Hz first natural frequency.<\/li>\n<li><strong>Solution:<\/strong> plain bearings were replaced with tilting-pad bearings, allowing safe operation to 15,000 rpm.<\/li>\n<\/ul>\n<h2>8. Standards, Practice, and Field Tools<\/h2>\n<ul>\n<li><strong><a href=\"https:\/\/vibromera.eu\/ga\/glossary\/api-684\/\">API 684<\/a>:<\/strong> requires a rotordynamic stability analysis for high-speed turbomachinery.<\/li>\n<li><strong>API 617:<\/strong> specifies bearing types and stability requirements for centrifugal compressors.<\/li>\n<li><strong>ISO 10814:<\/strong> provides guidance on bearing selection for stability.<\/li>\n<li><strong>Industry practice:<\/strong> tilting-pad bearings are standard for equipment running above 2\u00d7 the first critical speed.<\/li>\n<\/ul>\n<p>In the field, the everyday safeguard is to catch the precursor before the rotor ever reaches whip. A portable two-channel analyser such as the <a href=\"https:\/\/vibromera.eu\/ga\/product\/balanset-1\/\">Balanset-1A<\/a> lets an engineer record amplitude, <a href=\"https:\/\/vibromera.eu\/ga\/glossary\/phase\/\">phase<\/a> and spectrum during a controlled run-up and watch the sub-synchronous band directly \u2014 if a stable 1\u00d7 signature suddenly grows a locked, speed-independent peak near the first natural frequency, the rotor is on the edge of whip and the speed must be backed off. The same instrument confirms afterwards that the underlying unbalance is within tolerance, ruling it out as a contributing excitation. Shaft whip remains a catastrophic failure mode best handled by correct bearing selection and design; recognising its distinctive sub-synchronous, frequency-locked signature is what enables rapid diagnosis and the decisive emergency response that protects expensive high-speed equipment.<\/p>\n<hr>\n<p><a href=\"https:\/\/vibromera.eu\/ga\/glossary\/\">\u2190 Back to Main Index<\/a><\/p>","protected":false},"excerpt":{"rendered":"<p>Learn about shaft whip, a severe self-excited vibration instability in fluid-film bearings that occurs at high speeds, causing violent oscillations at natural frequency.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[109,111],"tags":[],"class_list":["post-235","glossary","type-glossary","status-publish","hentry","category-glossary","category-rotor-balancing"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/ga\/wp-json\/wp\/v2\/glossary\/235","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/ga\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/vibromera.eu\/ga\/wp-json\/wp\/v2\/types\/glossary"}],"version-history":[{"count":2,"href":"https:\/\/vibromera.eu\/ga\/wp-json\/wp\/v2\/glossary\/235\/revisions"}],"predecessor-version":[{"id":102183,"href":"https:\/\/vibromera.eu\/ga\/wp-json\/wp\/v2\/glossary\/235\/revisions\/102183"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/ga\/wp-json\/wp\/v2\/media?parent=235"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/ga\/wp-json\/wp\/v2\/categories?post=235"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/ga\/wp-json\/wp\/v2\/tags?post=235"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}