Worm Gear Torque Calculator

Calculator Inputs

Calculation Mode

Input Torque

Input Torque Unit

Target or Measured Output Torque

Target Torque Unit

Worm Starts

Wheel Teeth

Efficiency

Enter percent, such as 72.

Worm Speed

Use revolutions per minute.

Service Factor

Shock Factor

Safety Factor

Wheel Pitch Diameter

Pitch Diameter Unit

Result Torque Unit

Power Unit

Formula Used

Gear ratio: Ratio = Wheel teeth ÷ Worm starts

Output torque: Output torque = Input torque × Ratio × Efficiency

Required input torque: Input torque = Output torque ÷ Ratio ÷ Efficiency

Measured efficiency: Efficiency = Output torque ÷ Input torque ÷ Ratio

Output speed: Output speed = Worm speed ÷ Ratio

Power: Input power = Input torque × 2 × π × rpm ÷ 60

Wheel force: Tangential force = Output torque ÷ Pitch radius

Design torque: Design torque = Output torque × Service factor × Shock factor × Safety factor

How to Use This Calculator

Select the calculation mode.
Enter input torque or target output torque.
Add worm starts and wheel teeth.
Enter gearbox efficiency as a percent.
Add speed, service factor, shock factor, and safety factor.
Enter pitch diameter for force results.
Choose preferred output units.
Press calculate and review the result above the form.
Use the CSV or PDF buttons to save the output.

Example Data Table

Case	Input Torque	Starts	Teeth	Efficiency	Ratio	Output Torque
Light conveyor	8 N m	1	30	68%	30:1	163.2 N m
Index table	12 N m	2	40	72%	20:1	172.8 N m
Small lift	18 N m	1	50	60%	50:1	540 N m

Engineering Notes for Worm Gear Torque

A worm gear drive changes speed and torque through sliding contact. The worm turns the wheel through one or more starts. The wheel teeth set the ratio. A higher ratio usually raises torque. It also lowers output speed. Efficiency is important because worm drives lose power through friction. Heat can become a design limit. This calculator helps estimate these values before detailed sizing. Use verified ratings for final equipment selection.

Why Torque Changes

Input torque is multiplied by the gear ratio. Then the result is reduced by efficiency. For example, a 30:1 drive with 70 percent efficiency does not give perfect multiplication. It gives about twenty one times the input torque. This simple rule is useful during early design. It also helps compare motor choices and reducer sizes.

Important Design Factors

Real gearboxes need more checks than torque alone. Service factor covers long duty cycles. Shock factor covers starting loads or impact. Safety factor adds extra margin. The design torque shown by this page combines these factors. Use it when selecting shafts, keys, couplings, and housings. Check manufacturer limits before ordering parts.

Speed, Power, and Loss

Power should remain consistent after losses. The input power comes from torque and worm speed. Output power is lower because efficiency is less than one. The difference becomes heat. Slow moving, heavily loaded worm gears may need oil, fins, fans, or larger cases. Always check thermal ratings for continuous service.

Practical Use

Use accurate tooth counts and starts. Do not guess efficiency when the load is critical. Bronze wheels, steel worms, lubrication grade, lead angle, and surface finish all affect results. Use measured data when available. Use conservative values when data is missing. This approach gives safer estimates for Engineering work.

Reading the Results

Rated output torque is the calculated gearbox torque. Design torque is the stronger selection value. It includes service, shock, and safety multipliers. Tangential force shows the load at the wheel pitch circle. Output speed helps match conveyors, lifts, mixers, and tables. Loss power warns about heating. Review every value together, not separately.

Limits of the Estimate

This tool is for planning. It does not replace catalog data, bearing checks, or tooth stress analysis.

FAQs

What is worm gear torque?

It is the turning force produced at the worm wheel output shaft. It depends on input torque, gear ratio, and drive efficiency.

Why is efficiency important?

Worm gears use sliding contact. This creates friction and heat. Efficiency reduces the theoretical torque multiplication to a realistic output value.

How do I calculate gear ratio?

Divide the number of wheel teeth by the number of worm starts. A 40 tooth wheel and 2 start worm create a 20:1 ratio.

Can this calculator find required input torque?

Yes. Select required input torque mode. Enter the target output torque, ratio details, and efficiency. The tool returns the needed input torque.

What is design torque?

Design torque is rated output torque multiplied by service, shock, and safety factors. It helps choose stronger components for real use.

What efficiency should I enter?

Use manufacturer data when possible. If no data exists, use a conservative estimate based on lubrication, lead angle, load, and gearbox quality.

Why does output speed decrease?

The worm gear ratio reduces speed. Output speed equals worm speed divided by gear ratio. Higher ratios create slower output motion.

Can I use this for final gearbox selection?

Use it for planning and comparison. Final selection should also check thermal rating, tooth stress, bearing life, lubrication, and manufacturer limits.