Equivalent Dynamic Load (Bearing)
Calculate a bearing's equivalent dynamic load under combined loading, P = X·F_r + Y·F_a, from the radial load F_r (N), the axial load F_a (N) and the factors X and Y (dimensionless, tabulated by the maker per bearing type and the F_a/F_r ratio). Most bearings actually carry RADIAL (perpendicular to shaft) and AXIAL (along shaft) loads at once, but catalog life and capacity formulas are defined for an equivalent pure radial load. The equivalent dynamic load is that fictitious radial load that would give the SAME bearing life as the real load combination. The X and Y factors depend on the bearing type (deep-groove ball, angular contact, self-aligning, tapered roller) and the axial-to-radial ratio — for mainly radial loads, X≈1 and Y≈0 (axial negligible); when axial grows past a limit (the e factor), Y starts to contribute. Computing P correctly is the first step in any bearing design, since P enters the life formula L10 = (C/P)^p and the capacity check. Wrong factors (or ignoring axial load) give an incorrect life estimate. Enter the radial load, axial load and the X and Y factors.
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Carga dinâmica equivalente (rolamento)
A carga dinâmica equivalente de um rolamento sob cargas combinadas é P = X·F_r + Y·F_a, a partir da carga radial F_r, da carga axial F_a e dos fatores X e Y (tabelados pelo fabricante conforme o tipo de rolamento e a relação F_a/F_r). A maioria dos rolamentos sofre, na prática, cargas radiais (perpendiculares ao eixo) e axiais (ao longo do eixo) ao mesmo tempo, mas as fórmulas de vida e capacidade dos catálogos são definidas para uma carga radial pura equivalente. A carga dinâmica equivalente é justamente essa carga radial fictícia que produziria a mesma vida do rolamento que a combinação real. Os fatores X e Y dependem do tipo de rolamento (rígidos de esferas, de contato angular, autocompensadores, de rolos cônicos) e da proporção entre as cargas — para cargas predominantemente radiais, X≈1 e Y≈0; quando a axial cresce além de um limite (o fator e), Y passa a contribuir. Calcular P corretamente é o primeiro passo do dimensionamento de qualquer rolamento, pois é P que entra na fórmula de vida L10 = (C/P)^p e na verificação da capacidade. Usar fatores errados (ou ignorar a carga axial) leva a uma estimativa de vida incorreta. Informe a carga radial, a carga axial e os fatores X e Y.
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Equivalent Static Load (Bearing)
Calculate a bearing's equivalent static load, P_0 = X_0·F_r + Y_0·F_a, from the radial load F_r (N), the axial load F_a (N) and the static factors X_0 and Y_0 (tabulated by the maker). Unlike the equivalent dynamic load (related to FATIGUE under rotation), the equivalent static load is used to check the bearing under loads with the bearing STOPPED or turning very slowly, or under PEAK loads (shocks, momentary overloads). The risk here is not fatigue but PERMANENT DEFORMATION (indentation) of the races by the rolling elements: an excessive static load 'dents' permanent marks (brinelling) into the races, which then cause noise, vibration and early failure when the bearing turns again. The equivalent static load is the pure radial load that would cause the same maximum permanent deformation (at the most-loaded contact) as the real radial-axial combination. It is compared with the bearing's static load rating C0 (also tabulated) via the static safety factor s0 = C0/P0. This check is especially important in bearings carrying loads with the machine stopped (shafts of equipment parked under load) or subject to shocks. Enter the radial load, axial load and the static factors X0 and Y0.
L10 Life in Hours (Bearing)
Calculate a bearing's nominal L10 life in HOURS of operation, L10h = (10⁶ ÷ (60·n))·(C/P)^p, from the dynamic load rating C (N), the equivalent dynamic load P (N), the rotation n (rpm) and the exponent p (3 for ball bearings, 10/3 for roller bearings). L10 life is the core of bearing selection: the number of revolutions (or hours) that 90% of a batch of identical bearings reaches or exceeds before FATIGUE failure (spalling of races and rolling elements) — i.e., only 10% fail earlier (hence 'L10', the life with 90% reliability). The basic formula L10 = (C/P)^p gives life in MILLIONS of revolutions; dividing by the rotation (rpm × 60 min/h) converts to hours, the practical unit for machines. The result shows the huge load sensitivity: since the exponent is 3 (balls), DOUBLING the load cuts life to 1/8! So a slightly overloaded bearing lasts far less. The capacity C is tabulated in each bearing's catalog. This calculation decides whether a bearing meets the application's required life (typically 20,000-100,000 h for industrial machines) or whether a larger one is needed. Enter the dynamic capacity, the equivalent load, the rotation and the exponent.
Required Dynamic Capacity (Bearing)
Calculate the dynamic load rating C a bearing needs to reach a desired life, C = P·(L10)^(1/p), from the equivalent dynamic load P (N), the desired nominal life L10 (in millions of revolutions) and the exponent p (3 for balls, 10/3 for rollers). It is the INVERSE of the life calculation, and how bearing SELECTION is done in practice: the designer knows the load the bearing will carry (P) and the life it must reach (L10, derived from required operating hours and rotation), and computes the minimum needed dynamic capacity C. Then a bearing is chosen from the maker's catalog whose tabulated C is EQUAL OR GREATER than the required — and that fits the available dimensions (shaft and housing diameter). The dynamic capacity C is, by definition, the load giving an L10 life of exactly 1 million revolutions, and it is each bearing's 'rating' in the catalog. This calculation is the heart of sizing: it translates the application requirement (load and life) into the component spec (capacity), letting you pick the right bearing — neither undersized (early failure) nor oversized (needless cost and space). Enter the equivalent load, the desired life and the exponent.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.