Calculator Inputs
Example Data Table
| Case | Torque | Speed | Efficiency | Service Factor | Design Shaft Power |
|---|---|---|---|---|---|
| Pump Drive | 180 N·m | 960 RPM | 91% | 1.20 | 21.71 kW |
| Conveyor Gearbox | 420 N·m | 720 RPM | 93% | 1.15 | 36.39 kW |
| Fan System | 95 N·m | 1750 RPM | 89% | 1.10 | 19.13 kW |
| Agitator | 650 N·m | 360 RPM | 90% | 1.25 | 30.63 kW |
Formula Used
ω = 2πN / 60
P = T × ω
T = F × r
Adjusted Power = Base Power × Load Factor
Design Power = Adjusted Power × Service Factor
Input Power = Design Power / (Efficiency × Remaining Transmission Share)
Where P is shaft power in watts, T is torque in N·m, ω is angular speed in rad/s, N is rotational speed in RPM, F is tangential force, and r is effective radius.
Mechanical horsepower is calculated as watts divided by 745.699872. Metric horsepower is calculated as watts divided by 735.49875.
How to Use This Calculator
- Select the calculation method. Use torque directly, or derive it from force and radius.
- Enter shaft speed and choose the matching speed unit.
- Provide efficiency, service factor, expected load factor, and transmission loss.
- Add sizing margin when selecting a motor or upstream driver.
- Optionally enter operating hours and energy cost for daily energy estimates.
- Press Calculate Shaft Power to show the result above the form.
- Use the CSV or PDF buttons to export the calculated results.
Frequently Asked Questions
1. What does shaft power represent?
Shaft power is the mechanical power transmitted by a rotating shaft. It depends mainly on torque and rotational speed at the shaft.
2. Why include service factor?
Service factor increases design power to reflect shock, overloads, starts, and real operating uncertainty. It helps prevent undersized equipment selections.
3. What is the difference between shaft power and input power?
Shaft power is useful delivered mechanical output. Input power is higher because efficiency losses and transmission losses consume part of the supplied energy.
4. When should I use force and radius mode?
Use that mode when torque is not directly known. It is useful for belt pulls, tangential gear forces, brake arms, and lever calculations.
5. Can this calculator help with motor sizing?
Yes. The recommended motor size includes efficiency, transmission loss, and reserve margin, making it helpful for preliminary equipment selection.
6. Which horsepower value should I use?
Mechanical horsepower is common in many motor and machinery catalogs. Metric horsepower may appear in some regional specifications and legacy documents.
7. Why is load factor separate from service factor?
Load factor reflects expected running load relative to rated conditions. Service factor handles uncertainty, duty severity, and intermittent overload conditions.
8. Is the energy cost result exact?
No. It is an estimate based on entered hours, efficiency, and unit energy cost. Actual bills may vary with tariffs and operating patterns.