Free preliminary sizing tool
Gearbox ratio, torque and inertia calculator
Estimate output torque and speed through reduction gearing, plus load inertia reflected to the motor. Check assumptions before choosing a gearbox.
No registration is needed to calculate. Review the method, assumptions and worked example before using the figures.
Enter your calculation inputs
The initial values are an illustrative example. Replace them with your application figures. Calculations run in your browser and do not contact an AI service.
Method and assumptions
n_out = n_in / i; T_out = T_in × i × η; J_reflected = J_load / i²
Use a reduction ratio of at least 1, expressed as input revolutions per output revolution. Enter efficiency as a percentage and load inertia at the gearbox output in kg·m². The tool estimates forward motoring relationships at one operating point.
Illustrative worked example
Illustrative inputs: 2 Nm, 3,000 rpm, 10:1 reduction, 90% efficiency and 0.02 kg·m² load inertia give 18 Nm, 300 rpm and 0.0002 kg·m² reflected load inertia. These numbers do not establish that a particular gearbox can carry the duty.
What the result does not establish
Calculated torque is not a gearbox rating. Check continuous, peak, emergency-stop and bearing loads, duty, speed, backlash, stiffness and lifetime. Reflected load inertia excludes the gearbox, coupling and motor inertia. Reverse efficiency and backdrivability are not calculated.
These are general preliminary calculations, not an engineer-approved design, customer case study or product recommendation. Use the exact manufacturer's ratings and installation conditions for final selection.
Kollmorgen: application sizing guide · Gearbox selection guide
Pricing and availability
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- 01Tell us what you needSend a part number, or configure the application, quantities and timing.
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