This calculator sums selected mass terms into steady axial weight-force, defines an assumed projected contact radius as a selected fraction of ball radius, and divides force by that projected circular area. It does not calculate real contact stress, oil-film pressure or bearing capacity.
Spherical Step Bearing · Selected Projected-Area Ledger
Explore selected axial weight-force and projected-area arithmetic without treating assumed contact radius or 25 MPa as bearing design criteria.
Equation Used
- g is fixed at 9.81 m/s².
- The three entered mass terms are summed as a steady vertical weight load.
- Contact radius is an explicit selected fraction of ball radius, not a solved contact dimension.
- Pressure uses projected circular area πrc².
- The 25 MPa value is a comparison reference only.
- Elastic contact, lubrication, speed, viscosity, heat, friction, wear and safety are excluded.
Former contact-pressure and utilization claims are narrowed to projected-area pressure and a neutral ratio to a 25 MPa reference.
Selected projected-area reference
The cross-section identifies a spherical-ended vertical spindle and cup. Dimension and ledger graphics carry the exact selected values; contact extent and oil motion are illustrative.
What the calculator determines
Select three mass terms, ball radius and an assumed radius factor. The calculator reports selected axial weight-force, assumed contact radius, force divided by projected circular area, and its ratio to a disclosed 25 MPa reference.
Selected projected-area ledger
W=(m1+m2+m3)g; rc=kR; Aproj=πrc²; pproj=W/Aproj; ratio=100pproj/(25 MPa).
Selected-input example
At total selected mass 875 kg, R=30 mm and k=0.65, W=8583.75 N, rc=19.5 mm, and projected-area pressure is about 7.19 MPa.
Ledger, not bearing analysis
Actual contact extent is load- and material-dependent. Real design may require conformal contact, elastic deformation, pressure distribution, lubricant regime, speed, viscosity, film thickness, friction, heat, wear and material limits. The 25 MPa value is only a comparison reference.
Questions
Is πrc² the spherical contact area?
No. It is the projected circular area selected for this arithmetic comparison.
Does a ratio below 100% qualify the bearing?
No. The reference is not a manufacturer rating or universal allowable pressure.
References & Further Reading
- Wikipedia contributors. Plain bearing. Wikipedia
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