Calculate equivalent dynamic bearing load from radial and axial loads using typical factors for your bearing type, or enter catalogue X and Y factors.

Below e: X = 1, Y = 0. Above e: the listed X and Y. Choose Custom to enter catalogue values.

Typical ISO 281 factors (deep groove: conservative low-Fₐ/C₀ row). Use your catalogue’s e, X and Y for final design.

Application and output settings
Multiplier for shock or vibration. Default 1 = steady load.

Equivalent Dynamic Load Formula

The following equation is used to calculate the Equivalent Dynamic Load.

P = X × Fr + Y × Fa
  • Where P is the equivalent dynamic bearing load (use any consistent force unit, e.g., kN)
  • X is the radial load factor
  • Fr is the radial bearing load (same force unit as P)
  • Y is the axial load factor
  • Fa is the axial bearing load (same force unit as P)

Static or nominal load with a service factor

The static / nominal mode calculates Ffactored = Fnominal × f, using a known applied force and a dimensionless load factor. Enter a custom factor appropriate to the machine or design method. A bearing’s static load rating C0 is a capacity rating, not the applied load.

The bearing-service presets return a range: 1–1.2 times the nominal force for smooth operation without shock, 1.2–1.5 for normal operation, and 1.5–3 for operation with shock and vibration. These catalog-style ranges are screening estimates for bearing service. They are not universal impact factors or guaranteed upper and lower bounds for a structure. A time-dependent impact or vibration calculation also needs the relevant mass, stiffness, damping and loading history.

What is Equivalent Dynamic Load?

Definition:

In rolling-bearing life calculations, the equivalent dynamic bearing load (P) is a hypothetical constant load that would give the same basic rating life (L10) as the actual applied loading. For many radial bearings under combined radial (Fr) and axial (Fa) loading, it is commonly calculated using the catalog/standard factors X and Y: P = X·Fr + Y·Fa. The factors X and Y are not arbitrary constants; they are selected from the bearing manufacturer’s tables (or applicable standards) based on bearing type/design and the load ratio Fa/Fr (and sometimes other conditions).

How to Calculate Equivalent Dynamic Load?

Example Problem:

The following example outlines the steps and information needed to calculate equivalent dynamic load.

First, determine the radial and axial loads. For this example, these are 10 kN and 20 kN respectively.

Next, obtain the radial and axial load factors (X and Y) from the bearing catalog/standard. For this arithmetic example, assume X = 0.35 and Y = 0.65; verify applicable factors in the exact bearing’s catalogue before engineering use.

Finally, calculate the equivalent dynamic load using the formula above:

P = X * Fr + Y * Fa

P = .35*10 + .65 * 20

P = 16.5 kN