Radial versus axial bearing loads, ratings and equivalent load
Radial load acts across the shaft axis; axial or thrust load acts along it. Real assemblies may have both. A catalogue load rating is not the same as an unrestricted allowable machine load, and dynamic and static ratings answer different questions.
On this page10 sections ⌄
Radial, axial and combined loads: identify the direction first
A radial bearing is not necessarily incapable of taking any axial force. JTEKT identifies deep-groove and angular-contact ball bearings as examples that can carry combined loading, subject to the actual design. A pure thrust ball bearing has a different task; do not substitute it for a radial support merely because the bore matches.
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| Load | Direction relative to the shaft | What to check |
|---|---|---|
| Radial Fr | Perpendicular to the shaft axis | Shaft reactions and the bearing's radial capability |
| Axial / thrust Fa | Along the shaft axis | One or both directions; which bearing locates the shaft |
| Combined | Radial and axial components at the same time | The exact bearing's equivalent-load factors and arrangement |
| Moment | Tendency to tilt the supported assembly | Support spacing and system reactions, not a single scalar rating |
Dynamic C, static C0 and working load are different
Obtain X, Y and any decision threshold e from the applicable bearing data. A radial equivalent-load expression may use P = XFr + YFa, but the factors and the valid branch depend on construction and loading. A static check uses its own factors and criteria. Do not use one set everywhere.
JTEKT describes a branch for applicable single-row radial bearings where Fa/Fr does not exceed e: X = 1 and Y = 0, so P = Fr. With an illustrative radial input of 2 kN, that branch gives P = 2 kN. The example does not establish e or assign the branch to 6204, 608 or another model; verify the actual bearing before using it.
On smaller screens, scroll the table sideways to read all columns.
| Quantity | Used for | Not equivalent to |
|---|---|---|
| C, basic dynamic load rating | Fatigue-life calculation under the rating definition | Maximum vehicle weight or an unrestricted working load |
| C0, basic static load rating | Checking permanent contact deformation under static loading | The dynamic rating at zero rpm |
| P, dynamic equivalent load | A load producing the same calculated fatigue-life effect | Always Fr + Fa |
| P0, static equivalent load | A static contact-load assessment | Automatically the same value as P |
How much load can a 6204, 608 or another bearing carry?
Can I convert C from kN to kilograms and use it as payload?
No. A force conversion does not change the meaning of a rating. First calculate bearing reactions, duty and equivalent loads, then check fatigue life, static safety and operating limits. The same external payload can produce different bearing loads in different support arrangements.
Can a deep-groove ball bearing take thrust?
Some axial loading is possible for the appropriate construction, but the permitted condition must come from the exact bearing data. There is no universal percentage that safely covers all deep-groove bearings.
Which family should I investigate for combined loading?
Start with the product-family centre. Angular-contact ball and tapered-roller arrangements are relevant examples; load direction, magnitude, speed, stiffness and space decide the shortlist. This is a starting point, not a model selection approval.
What the evidence can — and cannot — tell you
| Observation or context | Interpretation to consider | Verification needed |
|---|---|---|
| Fr and Fa | Applied radial and axial load | Use the same force units and the actual duty case. |
| C and C0 | Catalogue dynamic and static ratings | Keep each with its matching calculation and bearing type. |
| Equivalent load P | A model-dependent representation of combined loading | Obtain the applicable factors and limits; do not assume X=Y=1. |
A practical investigation sequence
Identify and record
Draw the load directions and support positions before entering values in a calculator. Include the operating cases that can change reactions.
Check the context
Identify whether the exact bearing supports the required axial direction and combined duty. Single-direction and paired arrangements are not interchangeable.
Verify before acting
Use verified manufacturer factors and catalogue ratings in the load and life tools. Preserve whether the result is in newtons or kilonewtons.
Keep the decision traceable
Check static safety, life, speed, stiffness and arrangement constraints separately; passing one calculation is not a complete selection.
Capture the information a model search cannot guess
Keep this checklist with your inspection or comparison. Checking a box only records that you have collected the item; it does not certify the bearing.
0 of 4 information groups recorded.
Technical basis & editorial scope
Original BearingScope workflow, written for catalogue research and comparison. Manufacturer material is used to check principles, not copied as a product endorsement or substituted for model-specific instructions. Reviewed 1 October 2026.
- JTEKT Basic Bearing Knowledge — Bearing selection — Selection conditions, bearing types and operating environment
- JTEKT — Selection of bearing type — Load direction and construction selection principles
- JTEKT — Dynamic equivalent load — Dynamic equivalent load and construction-specific factors; numerical worked example is illustrative, not model data
- JTEKT — Basic static load rating and static equivalent load — Static rating and equivalent-load distinction
Source addresses and collection status are retained in the internal audit. No unpublished dimensions, torque settings, service intervals or interchange approvals are inferred.