KEVOS® MAKEOS · Power Transmission
Lead Screw Input Torque
What torque is needed to drive this axial load through a lead screw?
Calculate the torque needed to drive a steady axial load through a lead screw or ball screw at a known overall efficiency.
Open the calculatorRuns in your browser. No account needed.
How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Axial load | N | Total axial load to be moved, including gravity load on a vertical axis and process forces. |
| Screw lead (travel per revolution) | mm | Travel per revolution (pitch × number of starts). |
| Overall screw efficiency (as a fraction) | fraction 0–1 | Overall efficiency as a fraction from 0.01 to 1, from the screw manufacturer for this screw, nut material and lubrication. Enter 0.3 for 30%. |
Method and formulas
- Frictionless torque (N·m) = axial load (N) × lead (mm) / 1,000 / (2π).
- Input torque = frictionless torque / efficiency.
- Example: 2,000 N, 5 mm lead and efficiency 0.3 give 2,000 × 0.005 / (2π × 0.3) = 5.305165 N·m; the frictionless torque is 1.591549 N·m.
Limitations
- Steady motion only: acceleration torque, support bearing and seal drag, and preload torque are excluded.
- Back-driving and load holding are not checked. Whether a screw can be back-driven depends on its thread friction and lead angle; a brake may be needed on vertical axes.
- No certification or drive selection is implied.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size a motor or gearbox for a screw axis
- Compare lead screw and ball screw torque
- See how lead and efficiency change torque
Who it is for
- Design engineers
- Maintenance engineers
What you get
- Input torque at the entered efficiency (N·m)
- Frictionless torque at efficiency 1 (N·m)
Interpreting the result
- Lead screws commonly have much lower efficiency than ball screws, so the same load needs more torque and generates more heat.
Before relying on the result
- Use the manufacturer’s efficiency for the actual screw, nut and lubrication, not a generic figure.
- Add acceleration and drag torque and apply the drive manufacturer’s service factor before sizing a motor.
References
- Budynas R. G. and Nisbett J. K., Shigley’s Mechanical Engineering Design, 10th edition (McGraw-Hill, 2015), chapter 8, section on the mechanics of power screws. Topic reference; no source tables or recommended settings are reproduced.
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