Worm Gear Output Torque Calculator (Power-Based)
Calculate the output torque of a worm gearbox from the input power, speed, gear ratio and efficiency.
Method
Input torque T℅ₙ = 9550 × P(kW) / n(rpm)
Output torque = T℅ₙ × ratio × efficiency
Output speed = input speed / ratio
Note
Efficiency is applied once. Worm gear efficiency falls with ratio — about 90% at low ratios down to 40–50% at high ratios.
Frequently Asked Questions
How do I calculate worm gear output torque from power?
First find input torque = 9550 × kW / rpm, then multiply by ratio and efficiency.
Why the 9550 constant?
It converts kW and rpm to N·m: T(N·m) = 9550 × P(kW) / n(rpm).
Should I apply efficiency once or twice?
Once. Double-counting efficiency underestimates the output torque.
What efficiency do I use?
Use the gearbox-rated value; roughly 40–60% for valve worm gearboxes.
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