Can radial and axial bearing loads simply be added to obtain dynamic equivalent load?

LILY Bearing | 2026-10-28

Best answer

Use the manufacturer's bearing-specific load relationship

Radial and axial forces enter different contacts and affect fatigue according to the bearing design.

Catalog equivalent-load relationships use applicable factors and conditions to represent that effect. A vector magnitude such as √(Fr² + Fa²) answers a geometric force question, whereas dynamic equivalent load answers a rating-life question. They must not be treated as automatically interchangeable. The exact bearing type, contact angle or execution, and relevant load ratio can matter when selecting the factors. A combined-load calculation should consequently retain the catalog reference and the chosen factor conditions, rather than report only a final force with no derivation.

Audit the worksheet before trusting its life result

Find the separate radial and axial reactions at the bearing, the equivalent-load equation, each factor and the condition used to select it.

If a sheet simply writes “P = radial + axial,” ask why that relationship applies to the exact product. If it uses a vector resultant, check whether that value was intended for a different mechanical calculation. Preserve force units throughout and avoid borrowing factors from a nearby-looking bearing family. The review is complete only when the equation and inputs refer to the bearing being evaluated. This procedure does not provide missing catalog factors; it makes their absence visible before a life estimate becomes a design claim.