How to use this calculator
- Enter radial and axial load. Use the loads acting at the bearing location.
- Enter catalog dynamic factors. Use X and Y for the selected bearing and load ratio.
- Enter catalog static factors. Use X0 and Y0 for equivalent static load.
- Add load ratings. Enter C and C0 from the bearing catalog.
- Check S0. Compare the static safety factor against your target for shock or standstill loading.
How it works
The dynamic equivalent radial load reduces combined radial and axial loading to
one bearing-life input:
P = X x Fr + Y x Fa
The calculator does not let P fall below Fr for a radial bearing.
The static check uses the same catalog-factor pattern:
P0 = X0 x Fr + Y0 x Fa, then S0 = C0 / P0.
The required static rating is C0,req = S0,target x P0.
When the bearing is loaded by a gear, first resolve the mesh into tangential,
radial and axial components with the
gear mesh force calculator. Then use
the overhung load calculator and the
actual shaft layout to split those radial loads between bearings.
Worked example
Verified against the live calculator
With Fr = 5,000 N, Fa = 1,500 N, X = 1 and
Y = 0, the equivalent dynamic load is 5,000 N.
With X0 = 0.6 and Y0 = 0.5, the combined static value is
3,750 N, so P0 is taken as 5,000 N. A
20,000 N static rating gives S0 = 4.0.
Frequently asked questions
How do you calculate equivalent dynamic bearing load?
For a radial bearing under combined load, equivalent dynamic load is usually P = X*Fr + Y*Fa, where Fr is radial load, Fa is axial load, and X/Y come from the bearing catalog.
How do you calculate equivalent static bearing load?
Equivalent static load is commonly P0 = X0*Fr + Y0*Fa, with P0 not taken less than the radial load Fr for radial bearings.
What is bearing static safety factor?
Static safety factor is S0 = C0 / P0, where C0 is the catalog static load rating and P0 is the equivalent static bearing load.
Where do X, Y, X0 and Y0 come from?
They come from the bearing manufacturer and depend on bearing type, contact angle, internal geometry, load direction and the Fa/Fr ratio.
Is this the same as bearing life?
No. This calculator combines radial and axial loads into P and P0. Use P in the bearing L10 life calculator to estimate rating life.
Can I use this for tapered roller or angular contact bearings?
Yes as a first-pass calculation if you enter the correct catalog factors for that bearing arrangement. Preload and paired-bearing load sharing are separate checks.
Method & assumptions
- Radial-bearing equivalent-load format:
P = X x Fr + Y x Fa. - Static equivalent load is not taken below radial load.
- X/Y factors are user inputs because they depend on catalog tables and bearing type.
- Lubrication, speed, preload, fits, temperature, contamination, misalignment and paired-bearing load sharing are not modeled.