{"id":49,"date":"2025-10-31T00:25:51","date_gmt":"2025-10-31T00:25:51","guid":{"rendered":"https:\/\/vibromera.eu\/glossary\/bearing-fault-frequencies\/"},"modified":"2026-05-24T00:08:37","modified_gmt":"2026-05-24T00:08:37","slug":"bearing-fault-frequencies","status":"publish","type":"glossary","link":"https:\/\/vibromera.eu\/nb\/glossary\/bearing-fault-frequencies\/","title":{"rendered":"Hva er frekvenser av lagerfeil? Feildeteksjon"},"content":{"rendered":"<style>\n:root {\n  --navy: #0a2540;\n  --navy-light: #1a3a5c;\n  --blue: #2563eb;\n  --blue-light: #3b82f6;\n  --blue-pale: #dbeafe;\n  --blue-ghost: #eff6ff;\n  --beige: #f5f0e8;\n  --beige-dark: #e8dfd3;\n  --beige-light: #faf7f2;\n  --white: #ffffff;\n  --text: #1e293b;\n  --text-secondary: #475569;\n  --text-muted: #94a3b8;\n  --border: #cbd5e1;\n  --border-light: #e2e8f0;\n  --success: #059669;\n  --warning: #d97706;\n  --danger: #dc2626;\n  --shadow-sm: 0 1px 3px rgba(10,37,64,0.08);\n  --shadow-md: 0 4px 12px rgba(10,37,64,0.1);\n  --shadow-lg: 0 8px 30px rgba(10,37,64,0.12);\n  --shadow-xl: 0 16px 48px rgba(10,37,64,0.14);\n  --radius: 12px;\n  --radius-sm: 8px;\n  --radius-lg: 16px;\n}<\/p>\n<p>* { margin: 0; padding: 0; box-sizing: border-box; }<\/p>\n<p>body {\n  font-family: 'Source Sans 3', sans-serif;\n  color: var(--text);\n  background: var(--beige-light);\n  min-width: 1200px;\n  line-height: 1.7;\n  font-size: 16px;\n  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0.5px;\n}\n.form-group label .unit {\n  font-weight: 400;\n  text-transform: none;\n  color: var(--text-muted);\n}\n.form-group input, .form-group select {\n  padding: 10px 14px;\n  border: 1px solid var(--border);\n  border-radius: var(--radius-sm);\n  font-size: 15px;\n  font-family: 'JetBrains Mono', monospace;\n  background: var(--white);\n  color: var(--text);\n  transition: border-color 0.2s, box-shadow 0.2s;\n}\n.form-group input:focus, .form-group select:focus {\n  outline: none;\n  border-color: var(--blue);\n  box-shadow: 0 0 0 3px rgba(37,99,235,0.12);\n}\n.calc-btn {\n  grid-column: 1 \/ -1;\n  padding: 13px;\n  background: var(--blue);\n  color: var(--white);\n  border: none;\n  border-radius: var(--radius-sm);\n  font-size: 15px;\n  font-weight: 600;\n  font-family: 'Source Sans 3', sans-serif;\n  cursor: pointer;\n  transition: all 0.2s;\n  margin-top: 4px;\n}\n.calc-btn:hover {\n  background: var(--navy);\n  transform: translateY(-1px);\n  box-shadow: var(--shadow-md);\n}<\/p>\n<p>\/* Results Panel *\/\n.results-panel {\n  background: var(--navy);\n  border-radius: var(--radius-lg);\n  padding: 32px;\n  color: var(--white);\n  position: relative;\n  overflow: hidden;\n}\n.results-panel::before {\n  content: '';\n  position: absolute; inset: 0;\n  background: radial-gradient(circle at 100% 0%, rgba(37,99,235,0.2) 0%, transparent 60%);\n  pointer-events: none;\n}\n.results-panel .panel-title { color: var(--white); }\n.results-panel .panel-subtitle { color: rgba(255,255,255,0.5); }<\/p>\n<p>.results-grid {\n  display: grid;\n  grid-template-columns: 1fr 1fr;\n  gap: 16px;\n  position: relative;\n  z-index: 1;\n}\n.result-card {\n  background: rgba(255,255,255,0.08);\n  border: 1px solid rgba(255,255,255,0.1);\n  border-radius: var(--radius);\n  padding: 20px;\n  transition: all 0.3s;\n}\n.result-card:hover {\n  background: rgba(255,255,255,0.12);\n  transform: translateY(-2px);\n}\n.result-card .freq-label {\n  font-size: 12px;\n  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}<\/p>\n<p>\/* ===== QUICK REFERENCE TABLES ===== *\/\n.quick-ref {\n  padding: 40px 0 48px;\n  background: var(--beige-light);\n}\n.section-header {\n  margin-bottom: 28px;\n}\n.section-header h2 {\n  font-family: 'DM Serif Display', serif;\n  font-size: 30px;\n  color: var(--navy);\n  margin-bottom: 6px;\n}\n.section-header p {\n  font-size: 16px;\n  color: var(--text-secondary);\n}<\/p>\n<p>.ref-grid {\n  display: grid;\n  grid-template-columns: repeat(4, 1fr);\n  gap: 20px;\n  margin-bottom: 36px;\n}\n.ref-card {\n  background: var(--white);\n  border-radius: var(--radius);\n  padding: 24px;\n  border: 1px solid var(--border-light);\n  box-shadow: var(--shadow-sm);\n  transition: all 0.3s;\n  position: relative;\n  overflow: hidden;\n}\n.ref-card:hover {\n  box-shadow: var(--shadow-lg);\n  transform: translateY(-3px);\n}\n.ref-card::before {\n  content: '';\n  position: absolute;\n  top: 0; left: 0; right: 0;\n  height: 3px;\n}\n.ref-card.bpfo::before { background: var(--blue); }\n.ref-card.bpfi::before { background: var(--success); }\n.ref-card.bsf::before { background: var(--warning); }\n.ref-card.ftf::before { background: var(--danger); }<\/p>\n<p>.ref-card .card-abbr {\n  font-family: 'JetBrains Mono', monospace;\n  font-size: 20px;\n  font-weight: 700;\n  margin-bottom: 2px;\n}\n.ref-card.bpfo .card-abbr { color: var(--blue); }\n.ref-card.bpfi .card-abbr { color: var(--success); }\n.ref-card.bsf .card-abbr { color: var(--warning); }\n.ref-card.ftf .card-abbr { color: var(--danger); }<\/p>\n<p>.ref-card .card-name {\n  font-size: 14px;\n  font-weight: 600;\n  color: var(--text);\n  margin-bottom: 12px;\n}\n.ref-card .card-formula {\n  font-family: 'JetBrains Mono', monospace;\n  font-size: 11.5px;\n  background: var(--beige-light);\n  padding: 8px 10px;\n  border-radius: 6px;\n  margin-bottom: 12px;\n  color: var(--navy);\n  line-height: 1.5;\n  word-break: break-all;\n}\n.ref-card .card-typical {\n  font-size: 13px;\n  color: var(--text-secondary);\n  margin-bottom: 8px;\n}\n.ref-card .card-typical strong {\n  color: var(--text);\n  font-family: 'JetBrains Mono', monospace;\n  font-size: 12px;\n}\n.ref-card .card-description {\n  font-size: 13px;\n  color: var(--text-muted);\n  line-height: 1.5;\n}<\/p>\n<p>\/* Comparison table *\/\n.comparison-table-wrap {\n  background: var(--white);\n  border-radius: var(--radius);\n  border: 1px solid var(--border-light);\n  overflow: hidden;\n  box-shadow: var(--shadow-sm);\n  margin-bottom: 36px;\n}\n.comparison-table-wrap .table-title {\n  padding: 16px 24px;\n  font-weight: 600;\n  font-size: 15px;\n  background: var(--beige);\n  border-bottom: 1px solid var(--border-light);\n  color: var(--navy);\n}\ntable {\n  width: 100%;\n  border-collapse: collapse;\n}\ntable th {\n  background: var(--navy);\n  color: var(--white);\n  padding: 12px 16px;\n  font-size: 13px;\n  font-weight: 600;\n  text-transform: uppercase;\n  letter-spacing: 0.5px;\n  text-align: left;\n}\ntable td {\n  padding: 11px 16px;\n  font-size: 14px;\n  border-bottom: 1px solid var(--border-light);\n  color: var(--text);\n}\ntable tr:last-child td { border-bottom: none; }\ntable tr:hover td { background: var(--blue-ghost); }\ntable td:first-child { font-weight: 600; }\n.tag {\n  display: inline-block;\n  padding: 2px 8px;\n  border-radius: 4px;\n  font-size: 11px;\n  font-weight: 600;\n  text-transform: uppercase;\n  letter-spacing: 0.3px;\n}\n.tag.high { background: #fee2e2; color: #991b1b; }\n.tag.medium { background: #fef3c7; color: #92400e; }\n.tag.low { background: #d1fae5; color: #065f46; }\n.tag.very-low { background: var(--blue-pale); color: var(--navy); }\n.mono {\n  font-family: 'JetBrains Mono', monospace;\n  font-size: 13px;\n}<\/p>\n<p>\/* ===== MAIN CONTENT ===== *\/\n.main-content {\n  padding: 48px 0 64px;\n  background: var(--white);\n}\n.content-layout {\n  display: grid;\n  grid-template-columns: 1fr 300px;\n  gap: 48px;\n}<\/p>\n<p>\/* TOC sidebar *\/\n.toc-sidebar {\n  position: sticky;\n  top: 80px;\n  align-self: start;\n}\n.toc-box {\n  background: var(--beige-light);\n  border: 1px solid var(--beige-dark);\n  border-radius: var(--radius);\n  padding: 24px;\n}\n.toc-box h3 {\n  font-size: 14px;\n  font-weight: 700;\n  text-transform: uppercase;\n  letter-spacing: 0.5px;\n  color: var(--navy);\n  margin-bottom: 16px;\n}\n.toc-box a {\n  display: block;\n  padding: 6px 0;\n  font-size: 14px;\n  color: var(--text-secondary);\n  text-decoration: none;\n  border-left: 2px solid transparent;\n  padding-left: 12px;\n  transition: all 0.2s;\n}\n.toc-box a:hover {\n  color: var(--blue);\n  border-left-color: var(--blue);\n}\n.toc-box a.sub {\n  padding-left: 28px;\n  font-size: 13px;\n  color: var(--text-muted);\n}<\/p>\n<p>\/* Article content *\/\n.article-content h2 {\n  font-family: 'DM Serif Display', serif;\n  font-size: 28px;\n  color: var(--navy);\n  margin: 48px 0 16px;\n  padding-top: 20px;\n}\n.article-content h2:first-child { margin-top: 0; 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#fffbeb;\n  border-left-color: var(--warning);\n}\n.info-box.success {\n  background: #ecfdf5;\n  border-left-color: var(--success);\n}\n.info-box .box-title {\n  font-weight: 700;\n  font-size: 15px;\n  margin-bottom: 6px;\n  color: var(--navy);\n}\n.info-box p { margin-bottom: 8px; font-size: 14px; }\n.info-box p:last-child { margin-bottom: 0; }<\/p>\n<p>\/* Example block *\/\n.example-block {\n  background: var(--beige-light);\n  border: 1px solid var(--beige-dark);\n  border-radius: var(--radius);\n  padding: 28px;\n  margin: 24px 0;\n}\n.example-block .example-title {\n  font-family: 'DM Serif Display', serif;\n  font-size: 18px;\n  color: var(--navy);\n  margin-bottom: 16px;\n}<\/p>\n<p>\/* Stages visualization *\/\n.stages-timeline {\n  display: flex;\n  gap: 0;\n  margin: 24px 0;\n}\n.stage-item {\n  flex: 1;\n  padding: 20px;\n  position: relative;\n  border-top: 4px solid;\n}\n.stage-item:nth-child(1) { border-color: #86efac; background: #f0fdf4; }\n.stage-item:nth-child(2) { border-color: #fcd34d; background: #fefce8; }\n.stage-item:nth-child(3) { border-color: #fb923c; background: #fff7ed; }\n.stage-item:nth-child(4) { border-color: #f87171; background: #fef2f2; }\n.stage-item:first-child { border-radius: var(--radius-sm) 0 0 var(--radius-sm); }\n.stage-item:last-child { border-radius: 0 var(--radius-sm) var(--radius-sm) 0; }\n.stage-item .stage-name {\n  font-weight: 700;\n  font-size: 14px;\n  margin-bottom: 6px;\n  color: var(--navy);\n}\n.stage-item .stage-desc {\n  font-size: 13px;\n  color: var(--text-secondary);\n  line-height: 1.5;\n}<\/p>\n<p>\/* Procedure steps *\/\n.procedure-steps {\n  counter-reset: step;\n  margin: 24px 0;\n}\n.proc-step {\n  display: flex;\n  gap: 20px;\n  padding: 20px 0;\n  border-bottom: 1px solid var(--border-light);\n}\n.proc-step:last-child { border-bottom: none; }\n.proc-step::before {\n  counter-increment: step;\n  content: counter(step);\n  flex-shrink: 0;\n  width: 40px;\n  height: 40px;\n  background: var(--blue);\n  color: var(--white);\n  border-radius: 50%;\n  display: flex;\n  align-items: center;\n  justify-content: center;\n  font-weight: 700;\n  font-size: 16px;\n}\n.proc-step .step-content h4 {\n  margin: 0 0 4px;\n  font-size: 16px;\n  color: var(--navy);\n}\n.proc-step .step-content p {\n  margin: 0;\n  font-size: 14px;\n  color: var(--text-secondary);\n}<\/p>\n<p>\/* Inline table inside article *\/\n.article-table {\n  width: 100%;\n  margin: 20px 0;\n  border: 1px solid var(--border-light);\n  border-radius: var(--radius-sm);\n  overflow: hidden;\n}\n.article-table th {\n  padding: 10px 14px;\n  font-size: 12px;\n}\n.article-table td {\n  padding: 10px 14px;\n  font-size: 14px;\n}<\/p>\n<p>\/* ===== SHOP CTA ===== *\/\n.shop-cta {\n  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-light) 100%);\n  padding: 48px 0;\n  color: var(--white);\n  text-align: center;\n  position: relative;\n  overflow: hidden;\n}\n.shop-cta::before {\n  content: '';\n  position: absolute; inset: 0;\n  background: radial-gradient(circle at 50% 50%, rgba(37,99,235,0.15) 0%, transparent 60%);\n  pointer-events: none;\n}\n.shop-cta h2 {\n  font-family: 'DM Serif Display', serif;\n  font-size: 32px;\n  margin-bottom: 12px;\n  position: relative;\n}\n.shop-cta p {\n  font-size: 17px;\n  color: rgba(255,255,255,0.7);\n  margin-bottom: 28px;\n  max-width: 600px;\n  margin-left: auto;\n  margin-right: auto;\n  position: relative;\n}\n.shop-cta .cta-btn {\n  display: inline-flex;\n  align-items: center;\n  gap: 8px;\n  padding: 14px 36px;\n  background: var(--blue);\n  color: var(--white);\n  text-decoration: none;\n  border-radius: var(--radius-sm);\n  font-weight: 600;\n  font-size: 16px;\n  transition: all 0.2s;\n  position: relative;\n}\n.shop-cta .cta-btn:hover {\n  background: var(--blue-light);\n  transform: translateY(-2px);\n  box-shadow: 0 8px 24px rgba(37,99,235,0.3);\n}<\/p>\n<p>\/* ===== FOOTER ===== *\/\n.page-footer {\n  background: var(--beige);\n  border-top: 1px solid var(--beige-dark);\n  padding: 32px 0;\n  text-align: center;\n}\n.page-footer a {\n  color: var(--blue);\n  text-decoration: none;\n  font-weight: 500;\n}\n.page-footer p {\n  font-size: 14px;\n  color: var(--text-muted);\n}<\/p>\n<p>\/* ===== ANIMATIONS ===== *\/\n@keyframes fadeInUp {\n  from { opacity: 0; transform: translateY(16px); }\n  to { opacity: 1; transform: translateY(0); }\n}\n.animate-in {\n  animation: fadeInUp 0.5s ease-out forwards;\n}\n.delay-1 { animation-delay: 0.1s; opacity: 0; }\n.delay-2 { animation-delay: 0.2s; opacity: 0; }\n.delay-3 { animation-delay: 0.3s; opacity: 0; }\n.delay-4 { animation-delay: 0.4s; opacity: 0; }<\/p>\n<p>\/* Print styles *\/\n@media print {\n  .quick-nav, .shop-cta { display: none; }\n  .hero { padding: 20px 0; }\n  body { min-width: auto; }\n}\n<\/style>\n<p><!-- HERO --><\/p>\n<header class=\"hero\">\n<div class=\"hero-inner\">\n<div class=\"breadcrumb\">\n      <a href=\"https:\/\/vibromera.eu\/\">Home<\/a> \u2192 <a href=\"https:\/\/vibromera.eu\/glossary\/\">Glossary<\/a> \u2192 Bearing Fault Frequencies\n    <\/div>\n<h1>Understanding <span>Bearing Fault Frequencies<\/span><\/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\/nb\/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\/nb\/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\/nb\/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\/nb\/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=\"\/nb\/wp-json\/wp\/v2\/glossary\/49?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=\"Legg i handlekurv\"><i rel=\"tooltip\" data-original-title=\"Legg i handlekurv\" class=\"fas fa-cart-plus\"><\/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=\"\/nb\/wp-json\/wp\/v2\/glossary\/49?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=\"Legg i handlekurv: \u00abPortable balancer &amp; Vibration analyzer Balanset-1A\u00bb\" rel=\"nofollow\" data-success_message=\"\u00abPortable balancer &amp; Vibration analyzer Balanset-1A\u00bb ble lagt til i handlekurven\">Legg i handlekurv<\/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\/nb\/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\/nb\/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\/nb\/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\/nb\/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=\"\/nb\/wp-json\/wp\/v2\/glossary\/49?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=\"Legg i handlekurv\"><i rel=\"tooltip\" data-original-title=\"Legg i handlekurv\" class=\"fas fa-cart-plus\"><\/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=\"\/nb\/wp-json\/wp\/v2\/glossary\/49?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=\"Legg i handlekurv: \u00abVibration sensor\u00bb\" rel=\"nofollow\" data-success_message=\"\u00abVibration sensor\u00bb ble lagt til i handlekurven\">Legg i handlekurv<\/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\/nb\/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\/nb\/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\/nb\/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\/nb\/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=\"\/nb\/wp-json\/wp\/v2\/glossary\/49?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=\"Legg i handlekurv\"><i rel=\"tooltip\" data-original-title=\"Legg i handlekurv\" class=\"fas fa-cart-plus\"><\/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=\"\/nb\/wp-json\/wp\/v2\/glossary\/49?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=\"Legg i handlekurv: \u00abOptical Sensor (Laser Tachometer)\u00bb\" rel=\"nofollow\" data-success_message=\"\u00abOptical Sensor (Laser Tachometer)\u00bb ble lagt til i handlekurven\">Legg i handlekurv<\/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\/nb\/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\/nb\/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\/nb\/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\/nb\/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=\"\/nb\/wp-json\/wp\/v2\/glossary\/49?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=\"Legg i handlekurv\"><i rel=\"tooltip\" data-original-title=\"Legg i handlekurv\" class=\"fas fa-cart-plus\"><\/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=\"\/nb\/wp-json\/wp\/v2\/glossary\/49?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=\"Legg i handlekurv: \u00abBalanset-4\u00bb\" rel=\"nofollow\" data-success_message=\"\u00abBalanset-4\u00bb ble lagt til i handlekurven\">Legg i handlekurv<\/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\/nb\/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\/nb\/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\/nb\/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\/nb\/product\/magnet-stand\/\" title=\"Magnetic Stand Insize-60-kgf\">Magnetic Stand Insize-60-kgf<\/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>46.00<\/span> + VAT (if applicable)<\/h4><\/div>\n\t\t\t\t\t\t\t\t\t<div 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class=\"shop-item-title-link\" href=\"https:\/\/vibromera.eu\/nb\/product\/dynamic-balancer-balanset-1a\/\" title=\"Dynamic balancer \u201cBalanset-1A\u201d OEM\">Dynamic balancer \u201cBalanset-1A\u201d OEM<\/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>1,735.00<\/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=\"\/nb\/wp-json\/wp\/v2\/glossary\/49?add-to-cart=4193\" data-quantity=\"1\" data-product_id=\"4193\" data-product_sku=\"BS-1OEM\" class=\"button product_type_simple add_to_cart_button ajax_add_to_cart btn btn-just-icon btn-simple btn-default\" title=\"Legg i handlekurv\"><i rel=\"tooltip\" data-original-title=\"Legg i handlekurv\" class=\"fas fa-cart-plus\"><\/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=\"\/nb\/wp-json\/wp\/v2\/glossary\/49?add-to-cart=4193\" aria-describedby=\"woocommerce_loop_add_to_cart_link_describedby_4193\" data-quantity=\"1\" class=\"button product_type_simple add_to_cart_button ajax_add_to_cart\" data-product_id=\"4193\" data-product_sku=\"BS-1OEM\" aria-label=\"Legg i handlekurv: \u00abDynamic balancer \u201cBalanset-1A\u201d OEM\u00bb\" rel=\"nofollow\" data-success_message=\"\u00abDynamic balancer \u201cBalanset-1A\u201d OEM\u00bb ble lagt til i handlekurven\">Legg i handlekurv<\/a>\t<span id=\"woocommerce_loop_add_to_cart_link_describedby_4193\" 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 class=\"subtitle\">Complete guide to BPFO, BPFI, BSF &amp; FTF \u2014 the mathematically predictable vibration signatures that enable early bearing defect detection months before catastrophic failure.<\/p>\n<\/p><\/div>\n<\/header>\n<p><!-- QUICK NAV --><\/p>\n<nav class=\"quick-nav\">\n<div class=\"quick-nav-inner\">\n    <a href=\"#calculator\"><span class=\"icon\">\u2699<\/span> Calculator<\/a><br \/>\n    <a href=\"#quick-reference\"><span class=\"icon\">\ud83d\udcca<\/span> Quick Reference<\/a><br \/>\n    <a href=\"#four-frequencies\"><span class=\"icon\">\ud83d\udcd0<\/span> The Four Frequencies<\/a><br \/>\n    <a href=\"#formulas\"><span class=\"icon\">\ud83d\udd22<\/span> Formulas<\/a><br \/>\n    <a href=\"#spectra\"><span class=\"icon\">\ud83d\udcc8<\/span> Vibration Spectra<\/a><br \/>\n    <a href=\"#detection\"><span class=\"icon\">\ud83d\udd0d<\/span> Detection Techniques<\/a><br \/>\n    <a href=\"#practical\"><span class=\"icon\">\ud83d\udee0<\/span> Practical Application<\/a><br \/>\n    <a href=\"#predictive\"><span class=\"icon\">\u23f1<\/span> Predictive Maintenance<\/a>\n  <\/div>\n<\/nav>\n<p><!-- SUMMARY DASHBOARD: Calculator + Results --><\/p>\n<section class=\"summary-dashboard\" id=\"calculator\">\n<div class=\"container\">\n<div class=\"dashboard-grid\">\n<p>      <!-- Calculator --><\/p>\n<div class=\"calc-panel animate-in\">\n<h2 class=\"panel-title\">Bearing Fault Frequency Calculator<\/h2>\n<p class=\"panel-subtitle\">Enter bearing parameters to calculate all four characteristic frequencies<\/p>\n<div class=\"calc-form\" id=\"calcForm\">\n<div class=\"form-group\">\n            <label>Shaft Speed <span class=\"unit\">(RPM)<\/span><\/label><br \/>\n            <input type=\"number\" id=\"shaftRPM\" value=\"1800\" min=\"1\" step=\"1\">\n          <\/div>\n<div class=\"form-group\">\n            <label>Number of Rollers <span class=\"unit\">(N)<\/span><\/label><br \/>\n            <input type=\"number\" id=\"numBalls\" value=\"8\" min=\"2\" step=\"1\">\n          <\/div>\n<div class=\"form-group\">\n            <label>Ball\/Roller \u2300 <span class=\"unit\">(mm)<\/span><\/label><br \/>\n            <input type=\"number\" id=\"ballDia\" value=\"15.875\" min=\"0.1\" step=\"0.001\">\n          <\/div>\n<div class=\"form-group\">\n            <label>Pitch \u2300 <span class=\"unit\">(mm)<\/span><\/label><br \/>\n            <input type=\"number\" id=\"pitchDia\" value=\"58.5\" min=\"0.1\" step=\"0.001\">\n          <\/div>\n<div class=\"form-group\">\n            <label>Contact Angle <span class=\"unit\">(degrees)<\/span><\/label><br \/>\n            <input type=\"number\" id=\"contactAngle\" value=\"0\" min=\"0\" max=\"90\" step=\"0.1\">\n          <\/div>\n<div class=\"form-group\">\n            <label>Bearing Model <span class=\"unit\">(optional)<\/span><\/label><br \/>\n            <select id=\"presetBearing\" onchange=\"loadPreset()\"><option value=\"\">\u2014 Custom Values \u2014<\/option><option value=\"6205\">SKF 6205 (Deep Groove)<\/option><option value=\"6206\">SKF 6206 (Deep Groove)<\/option><option value=\"6207\">SKF 6207 (Deep Groove)<\/option><option value=\"6208\">SKF 6208 (Deep Groove)<\/option><option value=\"6305\">SKF 6305 (Deep Groove)<\/option><option value=\"6306\">SKF 6306 (Deep Groove)<\/option><option value=\"6307\">SKF 6307 (Deep Groove)<\/option><option value=\"6308\">SKF 6308 (Deep Groove)<\/option><option value=\"6309\">SKF 6309 (Deep Groove)<\/option><option value=\"6310\">SKF 6310 (Deep Groove)<\/option><option value=\"22205\">SKF 22205 (Spherical Roller)<\/option><option value=\"22206\">SKF 22206 (Spherical Roller)<\/option><option value=\"22210\">SKF 22210 (Spherical Roller)<\/option><option value=\"nu205\">SKF NU205 (Cylindrical Roller)<\/option><option value=\"nu206\">SKF NU206 (Cylindrical Roller)<\/option><option value=\"nu210\">SKF NU210 (Cylindrical Roller)<\/option><option value=\"7205\">SKF 7205 (Angular Contact)<\/option><option value=\"7206\">SKF 7206 (Angular Contact)<\/option><option value=\"7210\">SKF 7210 (Angular Contact)<\/option><option value=\"30205\">SKF 30205 (Tapered Roller)<\/option><option value=\"30206\">SKF 30206 (Tapered Roller)<\/option><\/select>\n          <\/div>\n<p>          <button class=\"calc-btn\" onclick=\"calculate()\">Calculate Fault Frequencies \u2192<\/button>\n        <\/div>\n<\/p><\/div>\n<p>      <!-- Results --><\/p>\n<div class=\"results-panel animate-in delay-1\">\n<h2 class=\"panel-title\">Calculated Frequencies<\/h2>\n<p class=\"panel-subtitle\">Results update after clicking Calculate<\/p>\n<div class=\"results-grid\" id=\"resultsGrid\">\n<div class=\"results-empty\">\n            <span class=\"icon\">\ud83d\udcc9<\/span><br \/>\n            Enter bearing parameters and click Calculate<br \/>to see fault frequencies\n          <\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n<p><!-- QUICK REFERENCE SECTION --><\/p>\n<section class=\"quick-ref\" id=\"quick-reference\">\n<div class=\"container\">\n<div class=\"section-header\">\n<h2>Quick Reference \u2014 The Four Fault Frequencies<\/h2>\n<p>Summary cards and comparison tables for rapid identification during vibration analysis<\/p>\n<\/p><\/div>\n<p>    <!-- 4 cards --><\/p>\n<div class=\"ref-grid\">\n<div class=\"ref-card bpfo animate-in delay-1\">\n<div class=\"card-abbr\">BPFO<\/div>\n<div class=\"card-name\">Ball Pass Frequency, Outer Race<\/div>\n<div class=\"card-formula\">BPFO = (N\u00d7n\/2) \u00d7 (1 + Bd\/Pd \u00d7 cos \u03b2)<\/div>\n<div class=\"card-typical\">Typical: <strong>3\u20135\u00d7 shaft speed<\/strong><\/div>\n<div class=\"card-description\">Most common bearing failure mode. Outer race is stationary, so defect position stays fixed relative to load zone.<\/div>\n<\/p><\/div>\n<div class=\"ref-card bpfi animate-in delay-2\">\n<div class=\"card-abbr\">BPFI<\/div>\n<div class=\"card-name\">Ball Pass Frequency, Inner Race<\/div>\n<div class=\"card-formula\">BPFI = (N\u00d7n\/2) \u00d7 (1 \u2212 Bd\/Pd \u00d7 cos \u03b2)<\/div>\n<div class=\"card-typical\">Typical: <strong>5\u20137\u00d7 shaft speed<\/strong><\/div>\n<div class=\"card-description\">Always higher than BPFO. Shows 1\u00d7 sidebands due to defect rotating through load zone.<\/div>\n<\/p><\/div>\n<div class=\"ref-card bsf animate-in delay-3\">\n<div class=\"card-abbr\">BSF<\/div>\n<div class=\"card-name\">Ball Spin Frequency<\/div>\n<div class=\"card-formula\">BSF = (Pd\/Bd \u00d7 n\/2) \u00d7 [1 \u2212 (Bd\/Pd)\u00b2 \u00d7 cos\u00b2 \u03b2]<\/div>\n<div class=\"card-typical\">Typical: <strong>1.5\u20133\u00d7 shaft speed<\/strong><\/div>\n<div class=\"card-description\">Less common. Defect strikes both races per revolution, creating complex vibration patterns.<\/div>\n<\/p><\/div>\n<div class=\"ref-card ftf animate-in delay-4\">\n<div class=\"card-abbr\">FTF<\/div>\n<div class=\"card-name\">Fundamental Train Frequency<\/div>\n<div class=\"card-formula\">FTF = (n\/2) \u00d7 (1 \u2212 Bd\/Pd \u00d7 cos \u03b2)<\/div>\n<div class=\"card-typical\">Typical: <strong>0.35\u20130.45\u00d7 shaft speed<\/strong><\/div>\n<div class=\"card-description\">Sub-synchronous frequency. Indicates cage wear, damage, or bearing-induced rotor instability.<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<p>    <!-- Comparison Table --><\/p>\n<div class=\"comparison-table-wrap\">\n<div class=\"table-title\">\ud83d\udcca Comparative Analysis of Bearing Fault Frequencies<\/div>\n<table>\n<thead>\n<tr>\n<th>Parameter<\/th>\n<th>BPFO (Outer Race)<\/th>\n<th>BPFI (Inner Race)<\/th>\n<th>BSF (Ball\/Roller)<\/th>\n<th>FTF (Cage)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Frequency Range<\/td>\n<td class=\"mono\">3\u20135\u00d7 RPM<\/td>\n<td class=\"mono\">5\u20137\u00d7 RPM<\/td>\n<td class=\"mono\">1.5\u20133\u00d7 RPM<\/td>\n<td class=\"mono\">0.35\u20130.45\u00d7 RPM<\/td>\n<\/tr>\n<tr>\n<td>Failure Probability<\/td>\n<td><span class=\"tag high\">~40% of failures<\/span><\/td>\n<td><span class=\"tag medium\">~30% of failures<\/span><\/td>\n<td><span class=\"tag low\">~10% of failures<\/span><\/td>\n<td><span class=\"tag very-low\">~20% of failures<\/span><\/td>\n<\/tr>\n<tr>\n<td>Sideband Pattern<\/td>\n<td>1\u00d7 sidebands (if loose)<\/td>\n<td>\u00b11\u00d7, \u00b12\u00d7 sidebands (always)<\/td>\n<td>Sidebands at FTF spacing<\/td>\n<td>Random, often erratic<\/td>\n<\/tr>\n<tr>\n<td>Detection Difficulty<\/td>\n<td><span class=\"tag low\">Easy<\/span><\/td>\n<td><span class=\"tag medium\">Moderate<\/span><\/td>\n<td><span class=\"tag high\">Hard<\/span><\/td>\n<td><span class=\"tag high\">Hard<\/span><\/td>\n<\/tr>\n<tr>\n<td>Best Detection Method<\/td>\n<td>Standard FFT<\/td>\n<td>Envelope analysis<\/td>\n<td>Envelope analysis<\/td>\n<td>Time waveform + envelope<\/td>\n<\/tr>\n<tr>\n<td>Typical Cause<\/td>\n<td>Fatigue, contamination, overload<\/td>\n<td>Fatigue, shaft misalignment<\/td>\n<td>Manufacturing defect, overload<\/td>\n<td>Poor lubrication, wear<\/td>\n<\/tr>\n<tr>\n<td>Load Zone Effect<\/td>\n<td>Fixed (defect in load zone = higher amp)<\/td>\n<td>Modulated (enters\/exits zone)<\/td>\n<td>Double impact per revolution<\/td>\n<td>May fluctuate randomly<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<p>    <!-- Severity Table --><\/p>\n<div class=\"comparison-table-wrap\">\n<div class=\"table-title\">\ud83d\udd25 Severity Assessment Guide \u2014 Bearing Defect Stages<\/div>\n<table>\n<thead>\n<tr>\n<th>Stage<\/th>\n<th>Spectrum Indicators<\/th>\n<th>Other Indicators<\/th>\n<th>Typical Time to Failure<\/th>\n<th>Recommended Action<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Stage 1 \u2014 Early<\/td>\n<td>Faint peaks near noise floor; visible only in envelope spectrum<\/td>\n<td>No audible noise; temperature normal; ultrasound may detect<\/td>\n<td class=\"mono\">6\u201324 months<\/td>\n<td>Monitor monthly; plan procurement<\/td>\n<\/tr>\n<tr>\n<td>Stage 2 \u2014 Developing<\/td>\n<td>Clear fault frequency peaks + 2\u20133 harmonics in standard FFT<\/td>\n<td>Possible slight temperature rise; intermittent noise at high load<\/td>\n<td class=\"mono\">1\u20136 months<\/td>\n<td>Monitor bi-weekly; schedule replacement<\/td>\n<\/tr>\n<tr>\n<td>Stage 3 \u2014 Advanced<\/td>\n<td>High-amplitude peaks, many harmonics, sideband families, rising noise floor<\/td>\n<td>Audible noise; temperature rise; visible vibration; grease discoloration<\/td>\n<td class=\"mono\">1\u20134 weeks<\/td>\n<td>Replace at earliest opportunity<\/td>\n<\/tr>\n<tr>\n<td>Stage 4 \u2014 Critical<\/td>\n<td>Chaotic spectrum; broadband energy; sub-harmonic peaks; 1\u00d7 RPM change<\/td>\n<td>Loud noise; high temperature; smoke possible; metal debris in grease<\/td>\n<td class=\"mono\">Days to hours<\/td>\n<td>Immediate shutdown and replacement<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<p>    <!-- Common Bearings Table --><\/p>\n<div class=\"comparison-table-wrap\">\n<div class=\"table-title\">\ud83d\udd29 Pre-Calculated Fault Frequencies for Common Bearings at 1800 RPM (30 Hz)<\/div>\n<table>\n<thead>\n<tr>\n<th>Bearing<\/th>\n<th>Type<\/th>\n<th>N (Balls)<\/th>\n<th>BPFO (Hz)<\/th>\n<th>BPFI (Hz)<\/th>\n<th>BSF (Hz)<\/th>\n<th>FTF (Hz)<\/th>\n<\/tr>\n<\/thead>\n<tbody id=\"preCalcTable\">\n        <\/tbody>\n<\/table><\/div>\n<\/p><\/div>\n<\/section>\n<p><!-- MAIN ARTICLE CONTENT --><br \/>\n<main class=\"main-content\" id=\"four-frequencies\"><\/p>\n<div class=\"container\">\n<div class=\"content-layout\">\n<article class=\"article-content\">\n<h2>Definition: What Are Bearing Fault Frequencies?<\/h2>\n<p><strong>Bearing fault frequencies<\/strong> (also called bearing defect frequencies or characteristic frequencies) are specific <a href=\"https:\/\/vibromera.eu\/glossary\/vibration\/\">vibration<\/a> frequencies generated when rolling elements\u2014balls or rollers\u2014in a bearing pass over defects such as cracks, spalls, pits, or surface fatigue on the bearing races or the rolling elements themselves. These frequencies are mathematically predictable based on the bearing&#8217;s internal geometry and the shaft&#8217;s rotational speed, making them invaluable diagnostic indicators for early detection of <a href=\"https:\/\/vibromera.eu\/glossary\/bearing-defects\/\">bearing defects<\/a>.<\/p>\n<p>Understanding and identifying these frequencies through <a href=\"https:\/\/vibromera.eu\/glossary\/vibration-analysis\/\">vibration analysis<\/a> allows maintenance personnel to detect bearing problems months\u2014sometimes years\u2014before they would become apparent through temperature rise, audible noise, or catastrophic failure. This enables planned maintenance and prevents costly unplanned downtime, secondary damage to shafts and housings, and potential safety incidents.<\/p>\n<div class=\"info-box\">\n<div class=\"box-title\">Why Mathematical Predictability Matters<\/div>\n<p>Unlike many vibration sources that produce unpredictable frequencies, bearing fault frequencies can be calculated precisely from bearing geometry. This means an analyst can know <em>exactly<\/em> which frequencies to look for in a <a href=\"https:\/\/vibromera.eu\/glossary\/spectrum\/\">spectrum<\/a>, eliminating guesswork and enabling automated monitoring systems that continuously watch for these specific signatures.<\/p>\n<\/p><\/div>\n<h2>The Four Fundamental Fault Frequencies \u2014 In Depth<\/h2>\n<p>Every rolling element bearing has four characteristic fault frequencies. Each corresponds to a different type of defect on a specific bearing component. Understanding the physical mechanism behind each frequency is essential for accurate diagnosis.<\/p>\n<h3>1. BPFO \u2014 Ball Pass Frequency, Outer Race<\/h3>\n<p>The <a href=\"https:\/\/vibromera.eu\/glossary\/bpfo\/\">BPFO<\/a> represents the rate at which rolling elements pass over a fixed point on the outer race. When a defect exists on the outer raceway surface, each rolling element strikes the defect as it passes, generating a repetitive impact at a predictable frequency.<\/p>\n<h4>Physical Mechanism<\/h4>\n<p>In most bearing installations, the outer race is stationary (pressed into the housing). This means that a defect on the outer race stays in a fixed position relative to the load zone\u2014the arc where the shaft load is transferred through the rolling elements. Because the defect&#8217;s position doesn&#8217;t change relative to the load, the impact force at each rolling element passage remains relatively constant. This produces a clean, strong vibration signal that is generally the easiest bearing defect to detect.<\/p>\n<h4>Diagnostic Characteristics<\/h4>\n<ul>\n<li><strong>Typical range:<\/strong> 3\u20135\u00d7 shaft speed for most standard bearings<\/li>\n<li><strong>Amplitude consistency:<\/strong> Relatively uniform amplitude because the defect is always in the same position relative to the load zone<\/li>\n<li><strong>Sideband behavior:<\/strong> Minimal <a href=\"https:\/\/vibromera.eu\/glossary\/sidebands\/\">sidebands<\/a> in typical installations; 1\u00d7 sidebands may appear if the outer race can rotate slightly in its housing (loose fit)<\/li>\n<li><strong>Harmonic development:<\/strong> As the defect grows, 2\u00d7, 3\u00d7, 4\u00d7 BPFO harmonics appear progressively<\/li>\n<li><strong>Detection ease:<\/strong> Easiest of the four fault types to detect due to consistent signal amplitude<\/li>\n<\/ul>\n<div class=\"info-box success\">\n<div class=\"box-title\">Practical Tip \u2014 Outer Race Load Zone<\/div>\n<p>If a BPFO peak is present but weak, the defect may be located outside the primary load zone. Changing the measurement direction (e.g., from vertical to horizontal) or changing the load on the bearing can move the load zone relative to the defect, potentially making it more visible in the spectrum.<\/p>\n<\/p><\/div>\n<h3>2. BPFI \u2014 Ball Pass Frequency, Inner Race<\/h3>\n<p>The <a href=\"https:\/\/vibromera.eu\/glossary\/bpfi\/\">BPFI<\/a> represents the rate at which rolling elements pass over a fixed point on the inner race. Since the inner race rotates with the shaft, a defect on the inner race moves in and out of the load zone with each revolution\u2014a critical difference from outer race defects.<\/p>\n<h4>Physical Mechanism<\/h4>\n<p>The inner race is press-fitted onto the shaft and rotates with it. A spall or pit on the inner race surface is struck by each rolling element as it passes, but unlike BPFO, the impact energy varies as the defect travels through the loaded and unloaded zones of the bearing. When the defect is in the load zone (bottom of a horizontal shaft bearing), the rolling elements are pressed firmly against both races, and the impact is strong. When the defect rotates to the unloaded zone (top), the rolling elements barely contact the inner race, and the impact may be very weak or absent.<\/p>\n<p>This amplitude modulation at 1\u00d7 shaft speed is the defining signature of inner race defects and produces characteristic sidebands in the frequency spectrum.<\/p>\n<h4>Diagnostic Characteristics<\/h4>\n<ul>\n<li><strong>Typical range:<\/strong> 5\u20137\u00d7 shaft speed (always higher than BPFO for the same bearing)<\/li>\n<li><strong>Amplitude modulation:<\/strong> Signal amplitude modulated at shaft speed (1\u00d7) as defect enters\/exits load zone<\/li>\n<li><strong>Sideband behavior:<\/strong> Almost always shows \u00b11\u00d7, \u00b12\u00d7 sidebands around BPFI \u2014 this is the key diagnostic indicator<\/li>\n<li><strong>Detection difficulty:<\/strong> Harder than BPFO because of varying amplitude; envelope analysis is often required for early detection<\/li>\n<li><strong>Common causes:<\/strong> Shaft <a href=\"https:\/\/vibromera.eu\/glossary\/misalignment\/\">misalignment<\/a> creating uneven stress, improper interference fit, shaft deflection fatigue<\/li>\n<\/ul>\n<div class=\"info-box warning\">\n<div class=\"box-title\">Critical Distinction \u2014 BPFI Sidebands<\/div>\n<p>The presence of 1\u00d7 sidebands around BPFI is often more diagnostically significant than the BPFI peak itself. In early-stage inner race defects, the sidebands may be more prominent than the fundamental BPFI frequency. Always check for sideband families when investigating inner race conditions.<\/p>\n<\/p><\/div>\n<h3>3. BSF \u2014 Ball Spin Frequency<\/h3>\n<p>The <a href=\"https:\/\/vibromera.eu\/glossary\/bsf\/\">BSF<\/a> represents the rotational speed of a rolling element (ball or roller) spinning on its own axis. When a rolling element has a surface defect\u2014a pit, spall, or flat spot\u2014it impacts both the inner and outer raceways as it rotates, creating a distinctive but complex vibration pattern.<\/p>\n<h4>Physical Mechanism<\/h4>\n<p>Each rolling element in a bearing spins on its own axis as it orbits around the bearing center. The spin rate depends on the ratio of pitch diameter to ball diameter and the shaft speed. A defect on a rolling element strikes the outer race once per ball revolution when it faces outward, and the inner race once per ball revolution when it faces inward. This produces impacts at 2\u00d7 BSF (two impacts per revolution of the defective element). Additionally, because the defective rolling element is carried around the bearing by the cage, its signal is modulated at the cage frequency (FTF).<\/p>\n<h4>Diagnostic Characteristics<\/h4>\n<ul>\n<li><strong>Typical range:<\/strong> 1.5\u20133\u00d7 shaft speed<\/li>\n<li><strong>Signature frequency:<\/strong> Often appears as 2\u00d7 BSF rather than 1\u00d7 BSF (double impact per revolution)<\/li>\n<li><strong>Sideband behavior:<\/strong> Sidebands at FTF (cage frequency) spacing around BSF peaks<\/li>\n<li><strong>Detection difficulty:<\/strong> Most difficult bearing defect to detect; rolling elements can develop flats that &#8220;self-heal&#8221; by re-polishing, causing intermittent symptoms<\/li>\n<li><strong>Occurrence rate:<\/strong> Less common than race defects; often a manufacturing or contamination issue<\/li>\n<\/ul>\n<h3>4. FTF \u2014 Fundamental Train Frequency<\/h3>\n<p>The <a href=\"https:\/\/vibromera.eu\/glossary\/ftf\/\">FTF<\/a> represents the rotational speed of the bearing cage (also called the retainer or separator). The cage holds the rolling elements in proper spacing around the bearing and rotates at a fraction of shaft speed.<\/p>\n<h4>Physical Mechanism<\/h4>\n<p>The cage rotates at a speed between 0 and shaft speed\u2014typically around 0.35\u20130.45\u00d7 shaft speed. Cage failures produce sub-synchronous vibration that can be erratic and difficult to distinguish from other low-frequency sources. Cage problems usually stem from inadequate lubrication, which causes the cage to drag against the rolling elements or races, creating wear, deformation, or cracking.<\/p>\n<h4>Diagnostic Characteristics<\/h4>\n<ul>\n<li><strong>Typical range:<\/strong> 0.35\u20130.45\u00d7 shaft speed (sub-synchronous)<\/li>\n<li><strong>Signal character:<\/strong> Often erratic and non-repetitive, making it harder to detect with standard FFT averaging<\/li>\n<li><strong>Modulation:<\/strong> May modulate other bearing frequencies \u2014 look for FTF sidebands around BPFO or BPFI<\/li>\n<li><strong>Detection:<\/strong> Best detected using <a href=\"https:\/\/vibromera.eu\/glossary\/time-waveform\/\">time waveform<\/a> analysis combined with envelope analysis; may also appear in shaft orbit patterns<\/li>\n<li><strong>Risk level:<\/strong> Cage failures can be catastrophic because cage fragments can jam the bearing, causing sudden seizure<\/li>\n<\/ul>\n<div class=\"info-box warning\">\n<div class=\"box-title\">Cage Failure Warning<\/div>\n<p>Unlike race defects that progress gradually, cage failures can escalate rapidly from minor to catastrophic. If FTF activity is detected, especially with erratic or broadband characteristics, increased monitoring frequency is strongly recommended. Cage fragment can cause sudden bearing seizure, potentially leading to shaft damage, equipment wreck, and safety hazards.<\/p>\n<\/p><\/div>\n<p>        <!-- FORMULAS SECTION --><\/p>\n<h2 id=\"formulas\">Formula Variables and Calculations Explained<\/h2>\n<p>The fault frequency formulas use the bearing&#8217;s internal geometric parameters. These dimensions define the relationship between shaft rotation and the movement of each bearing component:<\/p>\n<table class=\"article-table\">\n<thead>\n<tr>\n<th>Variable<\/th>\n<th>Name<\/th>\n<th>Description<\/th>\n<th>Units<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td class=\"mono\">N<\/td>\n<td>Number of rolling elements<\/td>\n<td>Total count of balls or rollers in the bearing<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td class=\"mono\">n<\/td>\n<td>Shaft rotational frequency<\/td>\n<td>Rotational speed of the inner race \/ shaft<\/td>\n<td>Hz or RPM<\/td>\n<\/tr>\n<tr>\n<td class=\"mono\">Bd<\/td>\n<td>Ball \/ roller diameter<\/td>\n<td>Diameter of one rolling element<\/td>\n<td>mm or inches<\/td>\n<\/tr>\n<tr>\n<td class=\"mono\">Pd<\/td>\n<td>Pitch diameter<\/td>\n<td>Diameter of the circle passing through centers of all rolling elements<\/td>\n<td>mm or inches<\/td>\n<\/tr>\n<tr>\n<td class=\"mono\">\u03b2<\/td>\n<td>Contact angle<\/td>\n<td>Angle between line connecting ball-race contact points and bearing radial plane. 0\u00b0 for deep groove, 15\u201340\u00b0 for angular contact and tapered roller.<\/td>\n<td>degrees<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<div class=\"info-box\">\n<div class=\"box-title\">Where to Find Bearing Geometry Data<\/div>\n<p>Most vibration analysis software includes bearing databases with pre-calculated parameters for tens of thousands of bearing models from all major manufacturers (SKF, FAG, NSK, NTN, Timken, etc.). Alternatively, manufacturer catalogs and online tools provide Bd, Pd, N, and \u03b2 for any bearing designation. For very old or uncommon bearings, the parameters can be estimated from measured outer diameter, inner bore, and bearing width.<\/p>\n<\/p><\/div>\n<h3>Simplified Estimation Rules<\/h3>\n<p>When exact bearing geometry is unavailable, these approximations work reasonably well for most standard deep groove ball bearings with contact angle \u2248 0\u00b0:<\/p>\n<ul>\n<li><strong>BPFO \u2248 0.4 \u00d7 N \u00d7 shaft speed<\/strong> \u2014 reliable within \u00b15% for most bearings<\/li>\n<li><strong>BPFI \u2248 0.6 \u00d7 N \u00d7 shaft speed<\/strong> \u2014 reliable within \u00b15%<\/li>\n<li><strong>FTF \u2248 0.4 \u00d7 shaft speed<\/strong> \u2014 reliable within \u00b110%<\/li>\n<li><strong>BSF varies<\/strong> too widely to estimate without geometry<\/li>\n<\/ul>\n<p>These approximations are useful for field diagnostics when a bearing database is not available, but precise calculations should always be used for formal analysis reports and trending programs.<\/p>\n<p>        <!-- SPECTRA SECTION --><\/p>\n<h2 id=\"spectra\">How Fault Frequencies Appear in Vibration Spectra<\/h2>\n<p>Understanding how bearing defects manifest in the frequency domain is crucial for accurate diagnosis. The spectral pattern changes significantly as a defect progresses through its life cycle.<\/p>\n<h3>Basic Spectral Appearance<\/h3>\n<p>When a bearing develops a localized defect (spall, crack, or pit), each passage of a rolling element over the defect generates a short-duration impact. This impact excites the bearing&#8217;s natural resonance frequencies (typically 1\u201330 kHz range), creating a modulated high-frequency signal. In the frequency spectrum, this appears as:<\/p>\n<ul>\n<li><strong>Primary peak:<\/strong> A distinct peak at the calculated fault frequency<\/li>\n<li><strong>Harmonics:<\/strong> Additional peaks at 2\u00d7, 3\u00d7, 4\u00d7 the fault frequency, increasing in number as the defect grows<\/li>\n<li><strong>Sidebands:<\/strong> Satellite peaks flanking the fault frequency, spaced at modulating frequency intervals<\/li>\n<li><strong>Amplitude growth:<\/strong> Progressive increase in fault frequency amplitude as defect area increases<\/li>\n<\/ul>\n<h3>Sideband Patterns \u2014 Key Diagnostic Signatures<\/h3>\n<p>Sidebands are secondary peaks that appear around a primary fault frequency, spaced at intervals determined by the modulating mechanism. They provide crucial information for confirming which bearing component is defective:<\/p>\n<ul>\n<li><strong>Inner race defects:<\/strong> BPFI peak with sidebands at \u00b11\u00d7, \u00b12\u00d7, \u00b13\u00d7 shaft speed. This is caused by the defect rotating through the load zone once per shaft revolution, modulating the impact energy.<\/li>\n<li><strong>Outer race defects:<\/strong> BPFO peak usually without sidebands in normally fitted bearings. If sidebands at 1\u00d7 shaft speed appear around BPFO, it may indicate the outer race is able to rotate slightly in its housing (loose fit condition).<\/li>\n<li><strong>Rolling element defects:<\/strong> BSF peaks (often 2\u00d7 BSF) with sidebands spaced at FTF (cage frequency). The cage carries the defective element around the bearing, causing the defect&#8217;s position relative to the load zone to change at the cage rotation rate.<\/li>\n<li><strong>Cage defects:<\/strong> FTF peak, often with harmonics, may show erratic amplitude variations. Cage frequency sidebands around BPFO or BPFI can indicate cage-related problems affecting rolling element spacing.<\/li>\n<\/ul>\n<h3>Defect Progression Stages<\/h3>\n<p>Bearing defects progress through recognizable stages, each with characteristic spectral patterns:<\/p>\n<div class=\"stages-timeline\">\n<div class=\"stage-item\">\n<div class=\"stage-name\">Stage 1 \u2014 Subsurface<\/div>\n<div class=\"stage-desc\">Micro-cracks below the race surface. Only detectable in the ultrasonic range (250 kHz+) using specialized techniques like Shock Pulse Method or high-frequency envelope analysis. Standard FFT shows nothing.<\/div>\n<\/p><\/div>\n<div class=\"stage-item\">\n<div class=\"stage-name\">Stage 2 \u2014 Slight Defect<\/div>\n<div class=\"stage-desc\">Surface <a href=\"https:\/\/vibromera.eu\/glossary\/spalling\/\">spalling<\/a> begins. Fault frequencies appear in the <a href=\"https:\/\/vibromera.eu\/glossary\/envelope-spectrum\/\">envelope spectrum<\/a> with 1\u20132 harmonics. Standard FFT may show very faint peaks. Natural resonance frequencies of bearing housing may be excited.<\/div>\n<\/p><\/div>\n<div class=\"stage-item\">\n<div class=\"stage-name\">Stage 3 \u2014 Definite Defect<\/div>\n<div class=\"stage-desc\">Spall has grown significantly. Clear fault frequency peaks with multiple harmonics and sideband families visible in standard FFT. Noise floor begins to rise. This is the optimal replacement window.<\/div>\n<\/p><\/div>\n<div class=\"stage-item\">\n<div class=\"stage-name\">Stage 4 \u2014 Severe \/ End-of-Life<\/div>\n<div class=\"stage-desc\">Extensive damage. Spectrum is chaotic with high broadband energy, random peaks, and elevated noise floor. Discrete fault frequencies may actually decrease as defect geometry becomes random. Immediate replacement required.<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<p>        <!-- DETECTION SECTION --><\/p>\n<h2 id=\"detection\">Detection Techniques \u2014 From Simple to Advanced<\/h2>\n<h3>Standard FFT Analysis<\/h3>\n<p>The <a href=\"https:\/\/vibromera.eu\/glossary\/fft\/\">Fast Fourier Transform<\/a> is the fundamental tool for vibration spectrum analysis. For bearing diagnostics, the procedure involves calculating the FFT of the raw vibration signal and examining it for peaks at the calculated bearing fault frequencies.<\/p>\n<p>Standard FFT analysis is effective for moderate to advanced defects (Stages 2\u20134) where fault frequency energy is strong enough to stand out above the noise floor and other vibration sources. However, it has significant limitations for early detection because bearing fault signals are typically low-energy, high-frequency impacts that can be masked by stronger low-frequency vibration from imbalance, misalignment, and other sources.<\/p>\n<h3>Envelope Analysis (Demodulation) \u2014 The Gold Standard<\/h3>\n<p><a href=\"https:\/\/vibromera.eu\/glossary\/envelope-analysis\/\">Envelope analysis<\/a> (also called High Frequency Demodulation or HFD) is the most effective technique for early bearing defect detection. It works by exploiting the physical nature of bearing impacts:<\/p>\n<ul>\n<li><strong>Step 1 \u2014 <a href=\"https:\/\/vibromera.eu\/glossary\/band-pass-filter\/\">Band-pass filter<\/a>:<\/strong> The raw vibration signal is filtered to isolate the high-frequency range (typically 500 Hz \u2013 20 kHz) where bearing impacts excite structural resonances. This removes dominant low-frequency vibration from imbalance, misalignment, etc.<\/li>\n<li><strong>Step 2 \u2014 Rectification:<\/strong> The filtered signal is rectified (absolute value) or passed through a Hilbert transform to extract the amplitude envelope.<\/li>\n<li><strong>Step 3 \u2014 Envelope FFT:<\/strong> The FFT of the envelope signal reveals the repetition rate of the impacts \u2014 which corresponds directly to bearing fault frequencies.<\/li>\n<\/ul>\n<p>Envelope analysis can detect bearing faults 6\u201312 months earlier than standard FFT methods, making it the preferred technique for <a href=\"https:\/\/vibromera.eu\/glossary\/predictive-maintenance\/\">predictive maintenance<\/a> programs. Most modern vibration analyzers include this capability as a standard feature.<\/p>\n<h3>Time-Domain Techniques<\/h3>\n<ul>\n<li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/shock-pulse-method\/\">Shock Pulse Method (SPM):<\/a><\/strong> Measures the intensity of mechanical shock waves generated by metal-to-metal impact in rolling bearings. Uses a resonant transducer (typically 32 kHz) to detect the short-duration, high-energy impacts from surface defects. Reports dBsv (decibels shock value) with normalised dBn and dBc values comparing to new and damaged bearing thresholds.<\/li>\n<li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/crest-factor\/\">Crest Factor:<\/a><\/strong> The ratio of peak vibration amplitude to RMS amplitude. A healthy bearing has a crest factor around 3; as impacting begins from surface defects, peak values increase while RMS stays relatively constant, pushing crest factor to 5\u20137 or higher. Note: in late-stage failure, both peak and RMS increase, and crest factor may drop back toward normal \u2014 a potential trap for unwary analysts.<\/li>\n<li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/kurtosis\/\">Kurtosis:<\/a><\/strong> A statistical measure of the &#8220;peakedness&#8221; of the vibration signal distribution. A normal (Gaussian) signal has kurtosis = 3. Early bearing defects create sharp impacts that increase kurtosis to 4\u20138 or higher, making it a sensitive early indicator. Like crest factor, kurtosis may decrease in late-stage failure as the signal becomes broadband.<\/li>\n<\/ul>\n<h3>Advanced Techniques<\/h3>\n<ul>\n<li><strong>Spectral Kurtosis:<\/strong> Maps kurtosis values across frequency bands to identify the optimal demodulation band for envelope analysis, replacing guesswork in filter selection.<\/li>\n<li><strong>Minimum Entropy Deconvolution (MED):<\/strong> Signal processing technique that enhances impulsiveness in vibration data, improving detection of periodic impacts from bearing faults in noisy signals.<\/li>\n<li><strong>Cyclostationary Analysis:<\/strong> Exploits the second-order cyclostationary properties of bearing fault signals (periodic modulation of random noise), providing superior detection in very early defect stages.<\/li>\n<li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/wavelet-analysis\/\">Wavelet Analysis<\/a>:<\/strong> Time-frequency decomposition that can isolate transient bearing impacts in both time and frequency simultaneously, useful when conventional methods are inconclusive.<\/li>\n<\/ul>\n<p>        <!-- PRACTICAL APPLICATION --><\/p>\n<h2 id=\"practical\">Practical Application \u2014 Step-by-Step Diagnostic Procedure<\/h2>\n<div class=\"procedure-steps\">\n<div class=\"proc-step\">\n<div class=\"step-content\">\n<h4>Identify Bearing<\/h4>\n<p>Determine the bearing model number and exact location. Check equipment drawings, bearing housing markings, or maintenance records. The model number is essential for calculating correct fault frequencies.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<div class=\"proc-step\">\n<div class=\"step-content\">\n<h4>Calculate Fault Frequencies<\/h4>\n<p>Use the bearing geometry parameters (N, Bd, Pd, \u03b2) and current shaft speed to calculate BPFO, BPFI, BSF, and FTF. Use the calculator above, bearing database software, or the formulas directly. Note: shaft speed may vary \u2014 measure actual RPM if possible.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<div class=\"proc-step\">\n<div class=\"step-content\">\n<h4>Collect Vibration Data<\/h4>\n<p>Mount an <a href=\"https:\/\/vibromera.eu\/glossary\/accelerometer\/\">accelerometer<\/a> on the bearing housing as close to the load zone as possible. Measure acceleration in all three axes. Use a sampling rate at least 10\u00d7 the highest frequency of interest (for envelope analysis, sample at 40\u2013100 kHz). Ensure the machine is running at normal operating load and speed.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<div class=\"proc-step\">\n<div class=\"step-content\">\n<h4>Analyze Spectrum<\/h4>\n<p>Examine both the standard FFT spectrum and the envelope spectrum for peaks at calculated fault frequencies. Look for BPFO, BPFI, BSF, and FTF and their harmonics. Use cursor read-out to verify frequencies match within \u00b12% of calculated values (allow for slight speed variation). A portable analyzer such as the <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> lets you capture the spectrum directly on the machine in the field and overlay the calculated fault frequencies, so a developing bearing defect can be confirmed without sending the rotor to a workshop.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<div class=\"proc-step\">\n<div class=\"step-content\">\n<h4>Confirm Diagnosis with Sidebands<\/h4>\n<p>Check for sideband patterns consistent with the identified defect type. BPFI should show 1\u00d7 sidebands; BSF should show FTF sidebands. The presence of correct sidebands confirms the diagnosis and distinguishes bearing frequencies from other coincidental peaks.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<div class=\"proc-step\">\n<div class=\"step-content\">\n<h4>Assess Severity<\/h4>\n<p>Evaluate the defect stage based on amplitude, number of harmonics, sideband development, noise floor elevation, and comparison with baseline\/historical data. Classify as Stage 1\u20134 using the severity guide above.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<div class=\"proc-step\">\n<div class=\"step-content\">\n<h4>Plan Maintenance Action<\/h4>\n<p>Based on severity assessment and equipment criticality, schedule bearing replacement during the next available maintenance window. Stages 1\u20132 allow extended monitoring; Stage 3 requires near-term planning; Stage 4 demands immediate attention. Document findings for trending purposes.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<h3>Worked Example \u2014 Complete Diagnosis<\/h3>\n<div class=\"example-block\">\n<div class=\"example-title\">Case: 22 kW Electric Motor \u2014 SKF 6308 Bearing at Drive End<\/div>\n<p><strong>Machine:<\/strong> 22 kW, 4-pole, 50 Hz induction motor driving a centrifugal pump. Operating speed: 1470 RPM (24.5 Hz). Drive-end bearing: SKF 6308 deep groove ball bearing.<\/p>\n<p><strong>Bearing Data:<\/strong> N = 8 balls, Bd = 15.875 mm, Pd = 58.5 mm, \u03b2 = 0\u00b0. Bd\/Pd ratio = 0.2714.<\/p>\n<p><strong>Calculated Frequencies:<\/strong><\/p>\n<ul>\n<li>BPFO = (8 \u00d7 24.5 \/ 2) \u00d7 (1 + 0.2714) = 98.0 \u00d7 1.2714 = <strong>124.6 Hz<\/strong><\/li>\n<li>BPFI = (8 \u00d7 24.5 \/ 2) \u00d7 (1 \u2212 0.2714) = 98.0 \u00d7 0.7286 = <strong>71.4 Hz<\/strong> \u2014 Wait, this doesn&#8217;t seem right. Let&#8217;s recalculate properly:<\/li>\n<\/ul>\n<p><em>Note: BPFI uses (1 \u2212 Bd\/Pd) while BPFO uses (1 + Bd\/Pd). BPFI should always be higher than BPFO. Looking at the standard formulas, in the canonical formulations where the outer race is fixed:<\/em><\/p>\n<ul>\n<li>BPFO = (N\/2) \u00d7 n \u00d7 (1 \u2212 Bd\/Pd \u00d7 cos \u03b2) = 4 \u00d7 24.5 \u00d7 (1 \u2212 0.2714) = 98.0 \u00d7 0.7286 = <strong>71.4 Hz<\/strong><\/li>\n<li>BPFI = (N\/2) \u00d7 n \u00d7 (1 + Bd\/Pd \u00d7 cos \u03b2) = 4 \u00d7 24.5 \u00d7 (1 + 0.2714) = 98.0 \u00d7 1.2714 = <strong>124.6 Hz<\/strong><\/li>\n<li>BSF = (Pd\/(2\u00d7Bd)) \u00d7 n \u00d7 [1 \u2212 (Bd\/Pd)\u00b2 \u00d7 cos\u00b2 \u03b2] = (58.5\/31.75) \u00d7 24.5 \u00d7 [1 \u2212 0.0737] = 1.8425 \u00d7 24.5 \u00d7 0.9263 = <strong>41.8 Hz<\/strong><\/li>\n<li>FTF = (n\/2) \u00d7 (1 \u2212 Bd\/Pd \u00d7 cos \u03b2) = 12.25 \u00d7 0.7286 = <strong>8.9 Hz<\/strong><\/li>\n<\/ul>\n<p><strong>Measurement Results (Envelope Spectrum):<\/strong> A prominent peak at 124.3 Hz (matching BPFI within 0.2%) with harmonics at 248.7 Hz and 373.1 Hz. Sideband peaks at 99.8 Hz and 148.8 Hz (\u00b124.5 Hz = \u00b11\u00d7 shaft speed around BPFI).<\/p>\n<p><strong>Diagnosis:<\/strong> Inner race defect confirmed \u2014 BPFI fundamental with 1\u00d7 sidebands is the classic signature. The presence of 2 harmonics but clear sideband structure indicates Stage 2\u20133 defect progression.<\/p>\n<p><strong>Recommended Action:<\/strong> Schedule bearing replacement within 2\u20134 weeks. Continue monitoring weekly until replacement. Inspect removed bearing for root cause (misalignment? improper fit? lubrication?). Verify alignment and fit during reinstallation.<\/p>\n<\/p><\/div>\n<p>        <!-- PREDICTIVE MAINTENANCE --><\/p>\n<h2 id=\"predictive\">Importance for Predictive Maintenance<\/h2>\n<p>Bearing fault frequencies form the cornerstone of effective predictive maintenance programs for rotating equipment. Their impact on maintenance strategy is profound:<\/p>\n<ul>\n<li><strong>Early Warning \u2014 6 to 24 Months Lead Time:<\/strong> Envelope analysis can detect bearing defects at the earliest stage of surface fatigue, providing months or even years of advance warning. This completely eliminates surprise failures and allows strategic procurement, staffing, and scheduling of maintenance activities.<\/li>\n<li><strong>Specific Component Diagnosis:<\/strong> Unlike overall vibration level monitoring, which can only say &#8220;something is wrong,&#8221; fault frequency analysis identifies exactly which bearing component is damaged \u2014 outer race, inner race, rolling element, or cage. This specificity enables precise repair scoping and parts ordering.<\/li>\n<li><strong>Trend Monitoring and Remaining Life Prediction:<\/strong> By tracking fault frequency amplitudes over time, analysts can establish deterioration rates and predict when a bearing will reach end of life. This trending capability enables just-in-time replacement\u2014not too early (wasting remaining bearing life) and not too late (risking failure).<\/li>\n<li><strong>Root Cause Analysis:<\/strong> The pattern of bearing defects across a machine fleet reveals systemic issues. Frequent outer race defects may indicate contamination; inner race defects may indicate shaft misalignment patterns; rolling element defects may indicate a bad batch from a supplier.<\/li>\n<li><strong>Secondary Damage Prevention:<\/strong> A failed bearing can destroy the shaft journal, damage the housing bore, wreck seal surfaces, contaminate lubricating systems, and even cause fire or explosion in hazardous environments. Early detection and planned replacement prevents all secondary damage.<\/li>\n<li><strong>Documented Cost Savings:<\/strong> Studies consistently show that predictive maintenance based on vibration analysis returns 10:1 or higher cost-benefit ratios compared to reactive (run-to-failure) maintenance. For critical equipment, the savings are even higher when production losses from unplanned downtime are included.<\/li>\n<\/ul>\n<div class=\"info-box success\">\n<div class=\"box-title\">Industry Best Practice<\/div>\n<p>Leading maintenance programs combine routine vibration data collection (monthly or quarterly for most equipment) with automated alarm systems that continuously monitor critical machines. Bearing fault frequencies should be configured as alarm parameters in online monitoring systems, with alert thresholds set based on historical baselines. This two-tier approach catches both gradual deterioration and sudden-onset defects.<\/p>\n<\/p><\/div>\n<p>Bearing fault frequencies are among the most powerful and well-proven diagnostic tools in vibration analysis. Their mathematical predictability, combined with modern envelope analysis and automated monitoring technology, enables reliable early detection of bearing defects. Mastering these concepts is essential for anyone involved in condition monitoring, reliability engineering, or predictive maintenance of rotating equipment.<\/p>\n<hr style=\"margin: 48px 0 24px; border: none; border-top: 1px solid var(--border-light);\">\n<p><a href=\"https:\/\/vibromera.eu\/glossary\/\">\u2190 Back to Glossary Index<\/a><\/p>\n<\/article>\n<p>      <!-- TOC SIDEBAR --><\/p>\n<aside class=\"toc-sidebar\">\n<div class=\"toc-box\">\n<h3>On This Page<\/h3>\n<p>          <a href=\"#calculator\">Fault Frequency Calculator<\/a><br \/>\n          <a href=\"#quick-reference\">Quick Reference Tables<\/a><br \/>\n          <a href=\"#four-frequencies\">Definition &#038; Overview<\/a><br \/>\n          <a class=\"sub\" href=\"#four-frequencies\">BPFO \u2014 Outer Race<\/a><br \/>\n          <a class=\"sub\" href=\"#four-frequencies\">BPFI \u2014 Inner Race<\/a><br \/>\n          <a class=\"sub\" href=\"#four-frequencies\">BSF \u2014 Ball Spin<\/a><br \/>\n          <a class=\"sub\" href=\"#four-frequencies\">FTF \u2014 Cage<\/a><br \/>\n          <a href=\"#formulas\">Formulas Explained<\/a><br \/>\n          <a href=\"#spectra\">Vibration Spectra<\/a><br \/>\n          <a class=\"sub\" href=\"#spectra\">Sideband Patterns<\/a><br \/>\n          <a class=\"sub\" href=\"#spectra\">Defect Progression<\/a><br \/>\n          <a href=\"#detection\">Detection Techniques<\/a><br \/>\n          <a class=\"sub\" href=\"#detection\">FFT Analysis<\/a><br \/>\n          <a class=\"sub\" href=\"#detection\">Envelope Analysis<\/a><br \/>\n          <a class=\"sub\" href=\"#detection\">Time-Domain<\/a><br \/>\n          <a class=\"sub\" href=\"#detection\">Advanced Methods<\/a><br \/>\n          <a href=\"#practical\">Practical Application<\/a><br \/>\n          <a href=\"#predictive\">Predictive Maintenance<\/a>\n        <\/div>\n<div class=\"toc-box\" style=\"margin-top: 24px; background: var(--navy); border-color: var(--navy);\">\n<h3 style=\"color: var(--white);\">Vibromera Equipment<\/h3>\n<p style=\"color: rgba(255,255,255,0.6); font-size: 13px; margin-bottom: 12px;\">Professional portable vibration analysis and balancing devices at accessible prices.<\/p>\n<p>          <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\" style=\"display: block; padding: 8px 14px; background: var(--blue); color: white; border-radius: 6px; text-align: center; font-weight: 600; font-size: 14px; text-decoration: none; margin-bottom: 8px; border-left: none;\">Balanset-1A \u2192<\/a><br \/>\n          <a href=\"https:\/\/vibromera.eu\/product\/balanset-4\/\" style=\"display: block; padding: 8px 14px; background: rgba(255,255,255,0.1); color: white; border-radius: 6px; text-align: center; font-weight: 600; font-size: 14px; text-decoration: none; border: 1px solid rgba(255,255,255,0.2); border-left: none;\">Balanset-4 \u2192<\/a>\n        <\/div>\n<\/aside><\/div>\n<\/p><\/div>\n<p><\/main><\/p>\n<p><!-- SHOP CTA --><\/p>\n<section class=\"shop-cta\">\n<div class=\"container\">\n<h2>Professional Vibration Analysis Equipment<\/h2>\n<p>Detect bearing faults early with Vibromera&#8217;s portable balancing and vibration analysis devices \u2014 professional capabilities at accessible prices.<\/p>\n<p>    <a href=\"https:\/\/vibromera.eu\/shop\/\" class=\"cta-btn\">Browse Equipment \u2192<\/a>\n  <\/div>\n<\/section>\n<p><!-- FOOTER --><\/p>\n<footer class=\"page-footer\">\n<div class=\"container\">\n<p><a href=\"https:\/\/vibromera.eu\/glossary\/\">\u2190 Back to Glossary<\/a> &nbsp;|&nbsp; 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