Calculator Inputs
Formula Used
This calculator uses standard flat-belt relations for power transmission and tension ratio. It is useful for study, estimation, and quick design screening.
Belt speed: v = πDN / 60
Euler-Eytelwein relation: T1 / T2 = eμθ
Power relation: P = (T1 - T2)v
Centrifugal tension: Tc = mv2
Initial tension estimate: T0 = (T1 + T2) / 2
- T1 is the tight side tension.
- T2 is the slack side tension.
- θ must be in radians for the exponential tension-ratio formula.
- When centrifugal tension is enabled, it is added to both sides.
How to Use This Calculator
- Enter transmitted power in kilowatts.
- Enter the driver pulley diameter and speed in rpm.
- Provide the coefficient of friction and belt wrap angle.
- Add belt mass per metre if high-speed effects matter.
- Set a design factor for conservative design review.
- Enable centrifugal tension when speed is high enough to matter.
- Press the calculate button to show results above the form.
- Use the CSV or PDF buttons to export your result set.
Example Data Table
Sample values are included below to demonstrate expected output format and unit handling.
| Power (kW) | Diameter (m) | RPM | μ | Wrap (deg) | Mass (kg/m) | Speed (m/s) | Tight Tension (N) | Slack Tension (N) | Initial Tension (N) |
|---|---|---|---|---|---|---|---|---|---|
| 5.00 | 0.30 | 960 | 0.30 | 165 | 0.85 | 15.080 | 766.445 | 434.872 | 600.658 |
Frequently Asked Questions
1) What is belt tension?
Belt tension is the pulling force carried by the belt. It determines grip, power transfer, slip resistance, and the load applied to shafts and bearings.
2) What are tight and slack side tensions?
The tight side carries the higher load while transmitting power. The slack side carries the lower load after the belt leaves the driven contact zone.
3) Why does wrap angle matter?
A larger wrap angle increases belt contact with the pulley. More contact raises available friction and increases the allowable tension ratio before slip begins.
4) How does friction affect results?
Higher friction increases the ratio between tight and slack tensions. That means the same power can be transmitted with different tension requirements and lower slipping risk.
5) When should centrifugal tension be included?
Include it when belt speed is high enough that mass-related outward force becomes noticeable. It is especially important for faster systems and lightweight, flexible belts.
6) Can this calculator be used for V-belts?
It is best for flat-belt style theory. V-belts introduce groove effects and different effective friction behavior, so dedicated V-belt design methods are more accurate.
7) What units should I use?
Use kilowatts for power, metres for pulley diameter, rpm for rotational speed, kilograms per metre for belt mass, and degrees for wrap angle.
8) How is initial tension estimated here?
This page estimates initial tension as the average of tight and slack side tensions. It is a practical screening value, not a manufacturer-specific setup instruction.