KEVOS® MAKEOS · Engineering
Thrust Bearing Pad Unit Load and PV
What unit load, sliding speed and PV does this pad or washer thrust bearing run at?
Pad area, unit load, mean sliding velocity and PV of a flat-land, tapered-land or tilting-pad thrust bearing (or a thrust washer), against allowable values.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Outside diameter | mm | Outer diameter of the pad ring. |
| Inside diameter | mm | Inner diameter of the pad ring. |
| Pad coverage of the ring | % | Share of the ring area covered by pads (100% for a plain washer; 75–85% typical for pads with oil grooves). |
| Thrust load | N | Axial load. |
| Speed | rpm | Speed. |
| Allowable unit load | MPa | Allowable unit load for the bearing type and material (hydrodynamic pads often 1.5–3.5 MPa; washers depend on material). |
| Allowable PV (0 = not checked) | MPa·m/s | PV limit for dry or boundary-lubricated washers; 0 to skip. |
Method and formulas
- Area = π(Do² − Di²)/4 × coverage.
- Unit load = W ÷ area.
- Mean velocity = π (Do + Di)/2 × n ÷ 60 000; PV = unit load × mean velocity.
- Example: 20000 N on a 150/80 mm ring at 80% coverage is 1.9771 MPa.
Limitations
- Screening by unit load and PV; hydrodynamic film thickness and temperature rise need the full design method.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a thrust washer or collar
- Screen a tilting-pad or tapered-land bearing size
- Compare pad geometries
Who it is for
- Design engineers
- Maintenance engineers
What you get
- Pad area and unit load
- Mean sliding velocity
- PV value
Interpreting the result
- If the unit load is too high, increase the outside diameter or the number of pads.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2338–2356. Topic reference; no source tables or recommended settings are reproduced.
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