KEVOS® MAKEOS · Engineering
Overhung Pulley Shaft Bush Check (Belt Pull, Bush Loads, P, V and PV)
For a belt pulley overhung on a shaft running in two plain bushes, what load does each bush carry, and are their pressure, sliding speed and PV within the bush material’s limits?
Check of the plain (sleeve) bearings carrying an overhung pulley: the belt pull from the power, speed and pulley diameter with a belt tension factor, the reactions at the near and far bushes from the overhang and bush spacing, and the projected-area pressure, sliding velocity and PV value of each bush (as the plain bearing PV tool), against the limits of the bush material.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Power through the pulley | kW | Power transmitted by the belt. |
| Shaft speed | rpm | Speed of the shaft. |
| Pulley pitch diameter | mm | Pitch diameter of the pulley. |
| Belt pull factor (shaft load ÷ effective pull) | Shaft load as a multiple of the effective belt pull (about 1.5 for V-belts, 2 or more for flat belts). | |
| Overhang (near bush centre to pulley centre) | mm | Distance from the centre of the bush nearest the pulley to the pulley centre. |
| Spacing between bush centres | mm | Distance between the two bush centres. |
| Bushes | ||
| Shaft diameter in the bushes | mm | Diameter of the shaft in the bushes. |
| Bush length | mm | Length of each bush. |
| Largest pressure for the material | MPa | Highest projected-area pressure the bush material allows. |
| Largest sliding speed for the material | m/s | Highest sliding speed the bush material allows. |
| Largest PV for the material | MPa·m/s | Highest PV the bush material allows. |
Method and formulas
- Torque = 9549 P ÷ n; effective pull = 2T ÷ D_p; shaft load = factor × effective pull.
- Near bush R₁ = F (L_b + a) ÷ L_b; far bush R₂ = F a ÷ L_b.
- P = R ÷ (d L); V = π d n; PV (as the plain bearing PV tool).
- Example: the belt loads the shaft with 613.88 N; the near bush carries 859.44 N at PV 1.05 MPa·m/s.
Limitations
- Steady belt load; start-up and shock raise the pull.
- Uniform bush pressure; shaft deflection concentrates load at the bush end near the pulley.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check bronze or polymer bushes on a pulley shaft
- Find the bush length needed for a belt drive
- Check a speed or power increase on a bushed shaft
Who it is for
- Maintenance engineers
- Design engineers
- Machine designers
What you get
- Torque, effective pull and shaft load
- Bush reactions
- P, V and PV of each bush
Interpreting the result
- A short overhang and widely spaced bushes keep the near bush load close to the belt pull itself.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2314–2337, 2473–2490. Topic reference; no source tables or recommended settings are reproduced.
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Open the Overhung Pulley Shaft Bush Check (Belt Pull, Bush Loads, P, V and PV) calculator
