{"id":100291,"date":"2026-02-15T20:32:08","date_gmt":"2026-02-15T20:32:08","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100291"},"modified":"2026-03-05T15:35:25","modified_gmt":"2026-03-05T15:35:25","slug":"vibration-iso20816-9-gears","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/nb\/calculators\/vibration-iso20816-9-gears\/","title":{"rendered":"Vibrasjonsgrenser for girdrift \u2014 ISO 20816-9 Gratisverkt\u00f8y"},"content":{"rendered":"\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Vibration Limits Calculator \u2014 ISO 20816-9 Gear Drives\",\"alternateName\":[\"ISO 20816-9 Calculator\",\"Gearbox Vibration Limits\",\"Gear Drive Vibration Evaluation\"],\"description\":\"Free online vibration zone evaluation calculator per ISO 20816-9 for gear drives.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/vibration-iso20816-9-gears\/\",\"applicationCategory\":\"Engineering Calculator\",\"operatingSystem\":\"Any (Web Browser)\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"EUR\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"datePublished\":\"2025-01-01\",\"dateModified\":\"2025-02-14\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true,\"featureList\":[\"ISO 20816-9 zone evaluation\",\"Parallel shaft, planetary, bevel gearboxes\",\"Speed category adjustment\",\"Gear mesh frequency reference\",\"Color-coded zone display\"],\"keywords\":\"vibration limits, ISO 20816-9, gear drive, gearbox, parallel shaft, planetary, bevel, zone A B C D\"}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[\n{\"@type\":\"Question\",\"name\":\"What machines does ISO 20816-9 cover?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"ISO 20816-9 applies to gear drives (gearboxes) used in industrial applications, including parallel shaft gearboxes, planetary\/epicyclic gear trains, and bevel gear units. It covers speed-increasing and speed-reducing gearboxes typically found in power generation, process industries, and general manufacturing.\"}},\n{\"@type\":\"Question\",\"name\":\"Why do speed categories matter for gearbox vibration limits?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Higher-speed gearboxes tend to produce lower overall vibration levels at the bearing housing because the forces are distributed over more cycles per second. Lower-speed gearboxes produce higher peak forces per revolution. Therefore, low-speed gearboxes (<1000 RPM) have higher zone limits than high-speed gearboxes (>3000 RPM).\"}},\n{\"@type\":\"Question\",\"name\":\"Why do planetary gearboxes have higher vibration limits?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Planetary (epicyclic) gearboxes have multiple gear meshes occurring simultaneously \u2014 the sun-planet meshes and the planet-ring gear meshes. This inherently produces more complex vibration signatures with higher overall levels. A multiplier of approximately 1.25\u00d7 is applied to the parallel shaft limits to account for this.\"}},\n{\"@type\":\"Question\",\"name\":\"What is gear mesh frequency and why is it important?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Gear mesh frequency (GMF) equals the number of teeth on a gear multiplied by its rotational speed in Hz. For example, a 50-tooth gear at 1500 RPM: GMF = 50 \u00d7 25 Hz = 1250 Hz. Sidebands around GMF indicate gear damage, while the GMF amplitude itself relates to gear quality, alignment, and loading. GMF and its harmonics are key diagnostic indicators.\"}},\n{\"@type\":\"Question\",\"name\":\"What should I do if gearbox vibration reaches Zone C?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Zone C indicates the gearbox is not suitable for continuous long-term operation. Investigate root causes: gear tooth damage (pitting, scuffing, cracking), bearing degradation, misalignment with coupled machines, lubrication issues, or overloading. Perform vibration spectrum analysis focusing on gear mesh frequency and its sidebands. Plan corrective action and increase monitoring frequency.\"}}\n]}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[\n{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/vibromera.eu\/\"},\n{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Calculators\",\"item\":\"https:\/\/vibromera.eu\/calculators\/\"},\n{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Vibration Limits ISO 20816-9\",\"item\":\"https:\/\/vibromera.eu\/calculators\/vibration-iso20816-9-gears\/\"}\n]}\n<\/script>\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.gstatic.com\" crossorigin>\n\n<link href=\"https:\/\/fonts.googleapis.com\/css2?family=DM+Sans:ital,opsz,wght@0,9..40,300;0,9..40,400;0,9..40,500;0,9..40,600;0,9..40,700;1,9..40,400&#038;family=JetBrains+Mono:wght@400;500;600&#038;family=Fraunces:opsz,wght@9..144,700;9..144,800&#038;display=swap\" rel=\"stylesheet\">\n\n<link rel=\"stylesheet\" href=\"https:\/\/cdn.jsdelivr.net\/npm\/katex@0.16.11\/dist\/katex.min.css\">\n\n<style>\n:root {\n    --vc-bg: #f4f1ec;\n    --vc-surface: #ffffff;\n    --vc-surface-alt: #f8f6f2;\n    --vc-ink: #1a1a1a;\n    --vc-ink-secondary: #5a5650;\n    --vc-ink-muted: #8a857e;\n    --vc-accent: #c85a2a;\n    --vc-accent-hover: #b04d22;\n    --vc-accent-light: #fdf0ea;\n    --vc-blue: #2a5c8c;\n    --vc-blue-light: #eaf1f8;\n    --vc-green: #2a7a4b;\n    --vc-green-light: #eaf8ef;\n    --vc-yellow: #a67c00;\n    --vc-yellow-light: #fef9e8;\n    --vc-red: #b91c1c;\n    --vc-red-light: #fef2f2;\n    --vc-border: #d9d4cc;\n    --vc-border-light: #e8e4dd;\n    --vc-shadow: 0 1px 3px rgba(26,26,26,0.06), 0 4px 12px rgba(26,26,26,0.04);\n    --vc-shadow-lg: 0 4px 12px rgba(26,26,26,0.08), 0 16px 40px rgba(26,26,26,0.06);\n    --vc-radius: 8px;\n    --vc-radius-lg: 12px;\n    --vc-font: 'DM Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;\n    --vc-mono: 'JetBrains Mono', 'Consolas', 'Monaco', monospace;\n    --vc-display: 'Fraunces', Georgia, serif;\n\n    --zone-a: #16a34a;\n    --zone-a-light: #dcfce7;\n    --zone-b: #ca8a04;\n    --zone-b-light: #fef9c3;\n    --zone-c: #ea580c;\n    --zone-c-light: #fff7ed;\n    --zone-d: #dc2626;\n    --zone-d-light: #fef2f2;\n}\n\n.vc-calculator {\n    font-family: var(--vc-font);\n    font-size: 15px;\n    line-height: 1.65;\n    color: var(--vc-ink);\n    max-width: 960px;\n    margin: 0 auto;\n    padding: 20px 16px 40px;\n    -webkit-font-smoothing: antialiased;\n}\n.vc-calculator *, .vc-calculator *::before, .vc-calculator *::after { box-sizing: border-box; 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}\n.vc-faq-a-inner p { margin:0 0 8px; }\n.vc-faq-a-inner p:last-child { margin-bottom:0; }\n.vc-faq-a-inner ul { margin:4px 0 8px 16px; padding:0; }\n.vc-faq-a-inner li { margin-bottom:3px; }\n\n.vc-related { display:flex; flex-wrap:wrap; gap:10px; margin-top:16px; }\n.vc-related-link { display:inline-block; padding:8px 16px; font-family:var(--vc-font); font-size:13px; font-weight:600; background:var(--vc-surface-alt); color:var(--vc-ink-secondary); border:1px solid var(--vc-border); border-radius:var(--vc-radius); text-decoration:none; transition:all 0.15s; }\n.vc-related-link:hover { border-color:var(--vc-accent); color:var(--vc-accent); background:var(--vc-accent-light); }\n\n.vc-promo { margin-top:24px; padding:20px; background:linear-gradient(135deg, var(--vc-accent-light), var(--vc-surface)); border:1px solid var(--vc-border); border-radius:var(--vc-radius-lg); display:flex; align-items:center; gap:16px; }\n.vc-promo-text { flex:1; font-size:14px; color:var(--vc-ink-secondary); }\n.vc-promo-text strong { color:var(--vc-ink); }\n.vc-promo-link { padding:8px 20px; font-size:13px; font-weight:700; color:#fff; background:var(--vc-accent); border-radius:var(--vc-radius); text-decoration:none; white-space:nowrap; transition:background 0.15s; }\n.vc-promo-link:hover { background:var(--vc-accent-hover); }\n\n.vc-footer { text-align:center; padding:32px 16px; font-size:13px; color:var(--vc-ink-muted); }\n.vc-footer a { color:var(--vc-accent); text-decoration:none; }\n.vc-footer a:hover { text-decoration:underline; }\n.vc-footer-links { margin-top:8px; font-size:12px; }\n.vc-footer-links a { margin:0 8px; }\n\n@media print {\n    .vc-section-body { max-height:none!important; }\n    .vc-faq-a { max-height:none!important; }\n    .vc-results { max-height:none!important; padding:24px!important; }\n    .vc-copy-btn, .vc-section-chevron, .vc-faq-chevron, .vc-presets, .vc-promo { display:none!important; }\n}\n<\/style>\n\n<div class=\"vc-calculator\" id=\"vc-iso20816-9\">\n\n<header class=\"vc-header\">\n    <p class=\"vc-header-eyebrow\">Free Engineering Tool #025<\/p>\n    <h1 class=\"vc-header-title\">Vibration Limits \u2014 Gear Drives<\/h1>\n    <p class=\"vc-header-subtitle\">Evaluate vibration severity for gearboxes per ISO 20816-9. Supports parallel shaft, planetary\/epicyclic, and bevel gear drives across speed categories.<\/p>\n    <div class=\"vc-badges\">\n        <span class=\"vc-badge\">ISO 20816-9<\/span>\n        <span class=\"vc-badge\">Zones A\/B\/C\/D<\/span>\n        <span class=\"vc-badge\">Gear Drives<\/span>\n    <\/div>\n<\/header>\n\n<div class=\"vc-card\">\n    <form class=\"vc-form\" id=\"vc-form\" autocomplete=\"off\">\n        <div class=\"vc-form-grid\">\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-geartype\">Gearbox Type<\/label>\n                <select class=\"vc-select\" id=\"vc-geartype\">\n                    <option value=\"parallel\" selected>Parallel Shaft<\/option>\n                    <option value=\"planetary\">Planetary \/ Epicyclic<\/option>\n                    <option value=\"bevel\">Bevel Gear<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-speed\">Speed Category<\/label>\n                <select class=\"vc-select\" id=\"vc-speed\">\n                    <option value=\"low\">Low (&lt;1000 RPM)<\/option>\n                    <option value=\"medium\" selected>Medium (1000\u20133000 RPM)<\/option>\n                    <option value=\"high\">High (&gt;3000 RPM)<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field vc-field-full\">\n                <label class=\"vc-label\" for=\"vc-value\">Measured Velocity <span class=\"vc-label-hint\">(mm\/s RMS)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-value\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 5.0\" value=\"5.0\">\n            <\/div>\n        <\/div>\n\n        <div class=\"vc-presets\">\n            <div class=\"vc-presets-label\">Quick presets<\/div>\n            <button type=\"button\" class=\"vc-preset-btn\" data-g=\"parallel\" data-s=\"medium\" data-v=\"5.0\">Parallel 1500 RPM 5.0 mm\/s<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-g=\"planetary\" data-s=\"low\" data-v=\"8.0\">Planetary 750 RPM 8.0 mm\/s<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-g=\"parallel\" data-s=\"high\" data-v=\"3.0\">High-speed 4500 RPM 3.0 mm\/s<\/button>\n        <\/div>\n    <\/form>\n\n    <div class=\"vc-results\" id=\"vc-results\">\n        <div class=\"vc-results-head\">\n            <h2 class=\"vc-results-title\">Results<\/h2>\n            <button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\">\n                <svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg>\n                Copy\n            <\/button>\n        <\/div>\n\n        <div class=\"vc-zone-bar\" id=\"vc-zone-bar\">\n            <div class=\"vc-zone-bar-seg zb-a\" id=\"zb-a\">A<\/div>\n            <div class=\"vc-zone-bar-seg zb-b\" id=\"zb-b\">B<\/div>\n            <div class=\"vc-zone-bar-seg zb-c\" id=\"zb-c\">C<\/div>\n            <div class=\"vc-zone-bar-seg zb-d\" id=\"zb-d\">D<\/div>\n        <\/div>\n        <div class=\"vc-zone-bar-labels\" id=\"vc-zone-labels\">\n            <span id=\"zl-a\"><\/span><span id=\"zl-b\"><\/span><span id=\"zl-c\"><\/span><span id=\"zl-d\"><\/span>\n        <\/div>\n\n        <div class=\"vc-result-grid\">\n            <div class=\"vc-rcard vc-rcard-primary\" id=\"vc-r-zone-card\">\n                <div class=\"vc-rcard-label\">Vibration Zone<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-zone\">\u2014<\/div>\n                <div class=\"vc-rcard-desc\" id=\"vc-r-zone-desc\"><\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Measured Value<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-measured\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Recommendation<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-action\" style=\"font-size:16px;\">\u2014<\/div>\n            <\/div>\n        <\/div>\n\n        <div class=\"vc-info-box\" id=\"vc-gmf-note\">\n            <p><strong>\u2139\ufe0f Gear Mesh Frequency:<\/strong> <span id=\"vc-gmf-text\">For gear diagnostics, also analyze the gear mesh frequency (GMF = number of teeth \u00d7 shaft speed in Hz) and its sidebands. Elevated sidebands around GMF indicate developing gear tooth damage.<\/span><\/p>\n        <\/div>\n\n        <table class=\"vc-zone-table\" id=\"vc-boundary-table\">\n            <thead><tr><th>Zone<\/th><th>Boundary<\/th><th>Description<\/th><\/tr><\/thead>\n            <tbody id=\"vc-boundary-body\"><\/tbody>\n        <\/table>\n    <\/div>\n<\/div>\n\n<!-- Theory -->\n<div class=\"vc-section vc-open\" id=\"vc-sec-theory\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\">\n        <span class=\"vc-section-toggle-text\">\n            <span class=\"vc-section-icon\">\ud83d\udcd8<\/span>\n            <span class=\"vc-section-title\">Theory &amp; Formulas<\/span>\n        <\/span>\n        <svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner vc-theory\">\n            <h3>ISO 20816-9 Scope<\/h3>\n            <p>ISO 20816-9 specifies vibration evaluation criteria for gear drives (gearboxes) used in industrial applications. It covers parallel shaft, planetary\/epicyclic, and bevel gear arrangements across various speed ranges.<\/p>\n            <div class=\"vc-formula-box\" id=\"vc-katex-1\"><\/div>\n\n            <h3>Parallel Shaft \u2014 Medium Speed (1000\u20133000 RPM)<\/h3>\n            <p>Base zone boundaries for parallel shaft gearboxes at medium operating speeds.<\/p>\n            <table class=\"vc-table\">\n                <thead><tr><th>Zone Boundary<\/th><th>Velocity (mm\/s RMS)<\/th><\/tr><\/thead>\n                <tbody>\n                    <tr><td>A\/B<\/td><td>3.5<\/td><\/tr>\n                    <tr><td>B\/C<\/td><td>7.1<\/td><\/tr>\n                    <tr><td>C\/D<\/td><td>11.2<\/td><\/tr>\n                <\/tbody>\n            <\/table>\n\n            <h3>Speed Category Adjustments<\/h3>\n            <table class=\"vc-table\">\n                <thead><tr><th>Speed Category<\/th><th>A\/B<\/th><th>B\/C<\/th><th>C\/D<\/th><\/tr><\/thead>\n                <tbody>\n                    <tr><td>Low (&lt;1000 RPM)<\/td><td>4.5<\/td><td>9.0<\/td><td>14.0<\/td><\/tr>\n                    <tr><td>Medium (1000\u20133000 RPM)<\/td><td>3.5<\/td><td>7.1<\/td><td>11.2<\/td><\/tr>\n                    <tr><td>High (&gt;3000 RPM)<\/td><td>2.8<\/td><td>5.6<\/td><td>9.0<\/td><\/tr>\n                <\/tbody>\n            <\/table>\n\n            <h3>Planetary \/ Epicyclic Gearboxes<\/h3>\n            <p>Planetary gearboxes have multiple simultaneous gear meshes, producing inherently higher vibration. A factor of 1.25\u00d7 is applied to the parallel shaft limits.<\/p>\n\n            <h3>Gear Mesh Frequency<\/h3>\n            <div class=\"vc-formula-box\" id=\"vc-katex-2\"><\/div>\n            <p>GMF and its harmonics are the primary diagnostic indicators for gear condition. Sidebands spaced at shaft speed around GMF indicate gear tooth damage patterns.<\/p>\n\n            <div class=\"vc-info-box\">\n                <p><strong>\u2139\ufe0f Note:<\/strong> The broadband velocity measurement used for zone classification does not distinguish between gear mesh vibration and other sources (unbalance, misalignment). Spectral analysis is essential for diagnosis.<\/p>\n            <\/div>\n\n            <div class=\"vc-warning-box\">\n                <p style=\"margin:0;font-size:14px;color:var(--vc-ink-secondary);\"><strong>\u26a0\ufe0f Important:<\/strong> Gearbox vibration is strongly influenced by load, alignment with coupled machines, lubrication condition, and gear tooth condition. Always compare measurements taken at consistent operating conditions.<\/p>\n            <\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<!-- Related -->\n<div class=\"vc-section\" id=\"vc-sec-related\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\">\n        <span class=\"vc-section-toggle-text\">\n            <span class=\"vc-section-icon\">\ud83d\udd17<\/span>\n            <span class=\"vc-section-title\">Related Calculators<\/span>\n        <\/span>\n        <svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner\">\n            <div class=\"vc-related\">\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-zones-iso20816-1\/\">ISO 20816-1 \u2014 General Guidelines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-3-industrial\/\">ISO 20816-3 \u2014 Industrial Machines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-5-hydro\/\">ISO 20816-5 \u2014 Hydro Turbines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-8-compressors\/\">ISO 20816-8 \u2014 Reciprocating Compressors<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-21-wind\/\">ISO 20816-21 \u2014 Wind Turbines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/residual-unbalance-iso1940\/\">Residual Unbalance (ISO 21940)<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-velocity\/\">Vibration Velocity (ISO 10816)<\/a>\n            <\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<!-- FAQ -->\n<div class=\"vc-section\" id=\"vc-sec-faq\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\">\n        <span class=\"vc-section-toggle-text\">\n            <span class=\"vc-section-icon\">\u2753<\/span>\n            <span class=\"vc-section-title\">Frequently Asked Questions<\/span>\n        <\/span>\n        <svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner\">\n            <div class=\"vc-faq-list\" id=\"vc-faq-list\"><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-promo\">\n    <div class=\"vc-promo-text\">\n        <strong>Vibromera \u2014 Portable Balancing &amp; Vibration Analysis<\/strong><br>\n        Professional vibration analyzers for gearbox condition monitoring and diagnostics. ISO 20816 compliant evaluation on-site. Used in 50+ countries.\n    <\/div>\n    <a class=\"vc-promo-link\" href=\"https:\/\/vibromera.eu\/\" target=\"_blank\" rel=\"noopener\">Learn More<\/a>\n<\/div>\n\n<footer class=\"vc-footer\">\n    <p>\u00a9 2024\u20132025 <a href=\"https:\/\/vibromera.eu\/\">Vibromera<\/a> \u2014 Engineering Calculators<\/p>\n    <p style=\"font-size:12px;margin-top:4px;\">Based on ISO 20816-9. Last updated: February 2025<\/p>\n    <div class=\"vc-footer-links\">\n        <a href=\"\/calculators\/engineering-calculators\/\">All Calculators<\/a>\n        <a href=\"https:\/\/vibromera.eu\/contacts\/\">Contact<\/a>\n    <\/div>\n<\/footer>\n\n<\/div>\n\n<script src=\"https:\/\/cdn.jsdelivr.net\/npm\/katex@0.16.11\/dist\/katex.min.js\"><\/script>\n<script>\n(function() {\n    'use strict';\n\n    var SLUG = 'vibration-iso20816-9-gears';\n\n    \/* Base limits for parallel shaft, by speed category *\/\n    var BASE_LIMITS = {\n        low:    { ab: 4.5, bc: 9.0, cd: 14.0 },\n        medium: { ab: 3.5, bc: 7.1, cd: 11.2 },\n        high:   { ab: 2.8, bc: 5.6, cd: 9.0 }\n    };\n\n    \/* Planetary multiplier *\/\n    var PLANETARY_FACTOR = 1.25;\n\n    var ZONE_DESC = {\n        A: 'Newly commissioned machines \u2014 excellent condition',\n        B: 'Acceptable for unrestricted long-term operation',\n        C: 'Not suitable for long-term operation \u2014 plan remedial action',\n        D: 'Dangerous vibration level \u2014 risk of damage, immediate action required'\n    };\n\n    var ZONE_ACTION = {\n        A: 'No action required \u2014 gearbox in excellent condition',\n        B: 'Continue normal operation and routine monitoring',\n        C: 'Investigate root cause; schedule corrective maintenance; increase monitoring',\n        D: 'Immediate shutdown or load reduction recommended \u2014 risk of damage'\n    };\n\n    function $(id) { return document.getElementById(id); }\n    function fmt(n, d) { if(isNaN(n)) return '\u2014'; var f=n.toFixed(d===undefined?2:d); return f.replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,''); }\n\n    function getZone(val, lim) {\n        if (val <= lim.ab) return 'A';\n        if (val <= lim.bc) return 'B';\n        if (val <= lim.cd) return 'C';\n        return 'D';\n    }\n\n    function getLimits(geartype, speed) {\n        var base = BASE_LIMITS[speed];\n        var factor = (geartype === 'planetary') ? PLANETARY_FACTOR : 1.0;\n        return {\n            ab: Math.round(base.ab * factor * 10) \/ 10,\n            bc: Math.round(base.bc * factor * 10) \/ 10,\n            cd: Math.round(base.cd * factor * 10) \/ 10,\n            unit: 'mm\/s RMS'\n        };\n    }\n\n    function calculate() {\n        var geartype = $('vc-geartype').value;\n        var speed = $('vc-speed').value;\n        var val = parseFloat($('vc-value').value);\n\n        if (isNaN(val) || val < 0) {\n            $('vc-results').classList.remove('vc-visible');\n            return;\n        }\n\n        var lim = getLimits(geartype, speed);\n        var zone = getZone(val, lim);\n\n        ['a','b','c','d'].forEach(function(letter) {\n            var seg = $('zb-' + letter);\n            seg.className = 'vc-zone-bar-seg zb-' + letter + (letter.toUpperCase() === zone ? ' zb-active' : ' zb-dim');\n        });\n\n        $('zl-a').textContent = '\u2264' + lim.ab;\n        $('zl-b').textContent = lim.ab + '\u2013' + lim.bc;\n        $('zl-c').textContent = lim.bc + '\u2013' + lim.cd;\n        $('zl-d').textContent = '>' + lim.cd;\n\n        var zoneCard = $('vc-r-zone-card');\n        zoneCard.className = 'vc-rcard vc-rcard-primary vc-zone-' + zone.toLowerCase();\n        $('vc-r-zone').textContent = 'Zone ' + zone;\n        $('vc-r-zone-desc').textContent = ZONE_DESC[zone];\n\n        $('vc-r-measured').innerHTML = fmt(val, 1) + ' <span class=\"vc-rcard-unit\">' + lim.unit + '<\/span>';\n        $('vc-r-action').textContent = ZONE_ACTION[zone];\n\n        var note = geartype === 'planetary' ? ' (planetary \u00d71.25 applied)' : '';\n        $('vc-gmf-text').textContent = 'For gear diagnostics, analyze the gear mesh frequency (GMF = number of teeth \u00d7 shaft speed in Hz) and its sidebands. Elevated sidebands around GMF indicate developing gear tooth damage.' + note;\n\n        var tbody = $('vc-boundary-body');\n        tbody.innerHTML =\n            '<tr class=\"zt-a\"><td><strong>Zone A<\/strong><\/td><td>\u2264 ' + lim.ab + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.A + '<\/td><\/tr>' +\n            '<tr class=\"zt-b\"><td><strong>Zone B<\/strong><\/td><td>' + lim.ab + ' \u2013 ' + lim.bc + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.B + '<\/td><\/tr>' +\n            '<tr class=\"zt-c\"><td><strong>Zone C<\/strong><\/td><td>' + lim.bc + ' \u2013 ' + lim.cd + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.C + '<\/td><\/tr>' +\n            '<tr class=\"zt-d\"><td><strong>Zone D<\/strong><\/td><td>&gt; ' + lim.cd + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.D + '<\/td><\/tr>';\n\n        $('vc-results').classList.add('vc-visible');\n\n        var u = new URL(window.location);\n        u.searchParams.set('geartype', geartype);\n        u.searchParams.set('speed', speed);\n        u.searchParams.set('value', val);\n        history.replaceState(null, '', u.toString());\n\n        var gearNames = { parallel: 'Parallel Shaft', planetary: 'Planetary', bevel: 'Bevel' };\n        var speedNames = { low: '<1000 RPM', medium: '1000-3000 RPM', high: '>3000 RPM' };\n        saveHistory({ geartype: geartype, speed: speed, value: val, zone: zone, _summary: gearNames[geartype] + ' (' + speedNames[speed] + ') ' + val + ' mm\/s \u2192 Zone ' + zone });\n    }\n\n    document.querySelectorAll('.vc-preset-btn').forEach(function(btn) {\n        btn.addEventListener('click', function(e) {\n            e.preventDefault();\n            $('vc-geartype').value = this.getAttribute('data-g');\n            $('vc-speed').value = this.getAttribute('data-s');\n            $('vc-value').value = this.getAttribute('data-v');\n            calculate();\n        });\n    });\n\n    $('vc-form').addEventListener('input', calculate);\n    $('vc-form').addEventListener('change', calculate);\n\n    $('vc-copy-btn').addEventListener('click', function() {\n        var text = 'Vibration Zone Evaluation \u2014 ISO 20816-9\\n' +\n            '\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\n' +\n            'Gearbox: ' + $('vc-geartype').options[$('vc-geartype').selectedIndex].text + '\\n' +\n            'Speed: ' + $('vc-speed').options[$('vc-speed').selectedIndex].text + '\\n' +\n            'Measured: ' + $('vc-r-measured').textContent + '\\n' +\n            'Zone: ' + $('vc-r-zone').textContent + '\\n' +\n            'Assessment: ' + $('vc-r-zone-desc').textContent + '\\n' +\n            '\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\n' +\n            'vibromera.eu\/calculators\/vibration-iso20816-9-gears\/';\n\n        if (navigator.clipboard) {\n            navigator.clipboard.writeText(text).then(function() {\n                var btn = $('vc-copy-btn');\n                btn.classList.add('vc-copied');\n                btn.innerHTML = '<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><polyline points=\"20 6 9 17 4 12\"\/><\/svg> Copied!';\n                setTimeout(function() {\n                    btn.classList.remove('vc-copied');\n                    btn.innerHTML = '<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg> Copy';\n                }, 2000);\n            });\n        }\n    });\n\n    document.querySelectorAll('.vc-section-toggle').forEach(function(btn) {\n        btn.addEventListener('click', function() {\n            var section = this.closest('.vc-section');\n            var isOpen = section.classList.contains('vc-open');\n            section.classList.toggle('vc-open');\n            this.setAttribute('aria-expanded', !isOpen);\n        });\n    });\n\n    var faqData = [\n        { q: 'What machines does ISO 20816-9 cover?', a: '<p>ISO 20816-9 applies to <strong>gear drives (gearboxes)<\/strong> used in industrial applications:<\/p><ul><li>Parallel shaft gearboxes (most common)<\/li><li>Planetary \/ epicyclic gear trains<\/li><li>Bevel gear units<\/li><\/ul><p>It covers speed-increasing and speed-reducing gearboxes in power generation, process industries, and manufacturing.<\/p>' },\n        { q: 'Why do speed categories matter for gearbox vibration limits?', a: '<p>Speed affects vibration characteristics significantly:<\/p><ul><li><strong>Low speed (&lt;1000 RPM):<\/strong> Higher peak forces per revolution, higher limits (A\/B = 4.5 mm\/s)<\/li><li><strong>Medium speed (1000\u20133000 RPM):<\/strong> Standard limits (A\/B = 3.5 mm\/s)<\/li><li><strong>High speed (&gt;3000 RPM):<\/strong> Lower limits (A\/B = 2.8 mm\/s) \u2014 less force per cycle but higher frequency excitation<\/li><\/ul><p>The speed category refers to the fastest shaft in the gearbox.<\/p>' },\n        { q: 'Why do planetary gearboxes have higher vibration limits?', a: '<p>Planetary (epicyclic) gearboxes have <strong>multiple simultaneous gear meshes<\/strong>:<\/p><ul><li>Sun gear meshes with 3\u20136 planet gears<\/li><li>Each planet meshes with the ring gear<\/li><li>Planet bearing forces contribute additional vibration<\/li><\/ul><p>This inherently produces higher overall vibration, so a multiplier of \u00d71.25 is applied to the parallel shaft limits.<\/p>' },\n        { q: 'What is gear mesh frequency and why is it important?', a: '<p><strong>Gear Mesh Frequency (GMF)<\/strong> = Number of teeth \u00d7 Shaft speed (Hz)<\/p><p>Example: 50-tooth gear at 1500 RPM \u2192 GMF = 50 \u00d7 25 = 1250 Hz<\/p><p>GMF analysis reveals:<\/p><ul><li>Gear tooth quality and wear condition<\/li><li>Sidebands indicate individual tooth damage<\/li><li>Harmonics of GMF indicate manufacturing quality<\/li><li>Modulation patterns reveal load distribution issues<\/li><\/ul>' },\n        { q: 'What should I do if gearbox vibration reaches Zone C?', a: '<p>For Zone C on a gearbox:<\/p><ul><li>Perform detailed spectrum analysis focusing on GMF and its sidebands<\/li><li>Check for gear tooth damage (pitting, scuffing, cracking)<\/li><li>Inspect bearing condition (inner\/outer race frequencies)<\/li><li>Verify alignment with coupled machines<\/li><li>Check lubrication \u2014 oil condition, temperature, flow rate<\/li><li>Plan corrective maintenance at next available opportunity<\/li><li>Increase monitoring frequency<\/li><\/ul>' }\n    ];\n\n    var faqList = $('vc-faq-list');\n    faqData.forEach(function(faq) {\n        faqList.innerHTML += '<div class=\"vc-faq-item\"><button type=\"button\" class=\"vc-faq-q\"><span>' + faq.q + '<\/span><svg class=\"vc-faq-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-faq-a\"><div class=\"vc-faq-a-inner\">' + faq.a + '<\/div><\/div><\/div>';\n    });\n    faqList.addEventListener('click', function(e) {\n        var btn = e.target.closest('.vc-faq-q');\n        if (!btn) return;\n        btn.closest('.vc-faq-item').classList.toggle('vc-open');\n    });\n\n    function saveHistory(entry) {\n        var key = 'vc_history_' + SLUG;\n        var arr = [];\n        try { arr = JSON.parse(localStorage.getItem(key)) || []; } catch(e) {}\n        entry._ts = new Date().toISOString();\n        arr.unshift(entry);\n        if (arr.length > 10) arr = arr.slice(0, 10);\n        try { localStorage.setItem(key, JSON.stringify(arr)); } catch(e) {}\n    }\n\n    function loadParams() {\n        var p = new URLSearchParams(window.location.search);\n        if (p.has('geartype')) $('vc-geartype').value = p.get('geartype');\n        if (p.has('speed')) $('vc-speed').value = p.get('speed');\n        if (p.has('value')) $('vc-value').value = p.get('value');\n    }\n\n    function renderFormulas() {\n        try {\n            katex.render('\\\\text{Zone} = \\\\begin{cases} A & v_{\\\\text{meas}} \\\\leq v_{A\/B} \\\\\\\\ B & v_{A\/B} < v_{\\\\text{meas}} \\\\leq v_{B\/C} \\\\\\\\ C & v_{B\/C} < v_{\\\\text{meas}} \\\\leq v_{C\/D} \\\\\\\\ D & v_{\\\\text{meas}} > v_{C\/D} \\\\end{cases}', $('vc-katex-1'), { displayMode: true, throwOnError: false });\n            katex.render('f_{\\\\text{GMF}} = Z \\\\times n \\\\quad \\\\text{where } Z = \\\\text{number of teeth},\\\\; n = \\\\text{shaft speed (Hz)}', $('vc-katex-2'), { displayMode: true, throwOnError: false });\n        } catch(e) {}\n    }\n\n    function init() {\n        loadParams();\n        renderFormulas();\n        calculate();\n    }\n\n    if (document.readyState === 'loading') {\n        document.addEventListener('DOMContentLoaded', init);\n    } else {\n        init();\n    }\n})();\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>Gratis online kalkulator for evaluering av vibrasjonssoner i henhold til ISO 20816-9 for girdrift. Evaluer lagerhusets hastighet mot grenseverdiene for sone A\/B\/C\/D for parallellaksel-, planet- og koniske girkasser ved forskjellige hastigheter.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100291","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100291","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":2,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100291\/revisions"}],"predecessor-version":[{"id":100740,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100291\/revisions\/100740"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/media?parent=100291"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/categories?post=100291"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/tags?post=100291"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}