Bearing catalog capacity alone does not select the system: the local contact between the radial roller and steel profile must also be checked.
Why bearing load rating is not the whole answer
A combined roller bearing may have a high basic dynamic or static load rating, but the complete guide system also depends on the contact between the radial roller and its steel profile. Load is transferred through a comparatively small contact zone. Excessive local stress can permanently indent the rail even when the internal bearing rating appears adequate.
For this reason, preliminary selection should check both the bearing rating and the allowable profile load. The weaker part of the assembled system controls the practical limit.
Start with the load arrangement
Record the operating load P, direction of movement, number of bearings, distance between bearing centres and the distance from the load centre to the guide. A cantilevered load creates a moment, so the most heavily loaded bearing can carry substantially more than total load divided by bearing count.
- Simple horizontal: establish how the payload and carriage weight share across the load-carrying bearings.
- Vertical mast: include lifted mass, carriage mass, acceleration, braking and any offset from the guide plane.
- Cantilever: include the moment created by load multiplied by its offset from the support.
- Telescopic system: check every extension stage because overlap and bearing spacing change through travel.
Data needed for a defensible check
- Maximum operating and abnormal loads in newtons
- Load centre, bearing spacing and rail spacing in millimetres
- Number and position of bearings
- Profile designation, cross-section and steel grade
- Shock, acceleration, duty cycle and expected deflection
- Required life, travel speed and environment
How to use the online screen
Our combined bearing selection tool estimates a screening reaction and compares it with verified standard-series profile-load values. It is intended to narrow the starting size, not to replace the contact-pressure, structure and deflection calculation.
When manual review is required
Use an application drawing when the system has uneven support, more than two rails, moving centres of gravity, overhead loads, significant acceleration, impact, welded rail supports or non-standard profiles. Jumbo and special bearings also require execution-specific data. Submit the load diagram and profile section through the technical review form.
Technical note: This guide supports preliminary sourcing. Confirm the controlled drawing, tolerances, load capacity and application requirements before ordering or installation.