Valve Operating Torque → Gearbox Selector
Size a worm gearbox for a valve. Enter the valve’s operating torque and a safety factor to get the required gearbox output torque, and the input torque at a chosen ratio.
Method
Pick the lowest standard ratio whose rated output torque meets the requirement.
Notes
Valve worm gearboxes are typically 40–60% efficient. Higher ratio gives more output torque and self-locking, but more turns to operate.
Frequently Asked Questions
How do I size a worm gearbox for a valve?
Multiply the valve operating torque by a safety factor (≥1.25) to get the required gearbox output torque, then pick a gearbox rated above it.
How do I find the input torque?
Divide the required output torque by (ratio × efficiency).
What efficiency should I use?
Around 40–60% for valve worm gearboxes; lower for high ratios.
Why use a worm gearbox on a valve?
It multiplies torque, reduces handwheel effort, and self-locks to hold the valve position with no power.
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