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Engineering Kit

Planetary gear calculator

A free online planetary gear calculator for epicyclic trains. Set the sun and ring tooth counts and the planet count, and the train rebuilds and animates, with the planet teeth following the concentric constraint automatically.

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Epicyclic gear train schematic with the sun gear, three planets on the carrier and the internal ring gear labelled.

Try it in your browser

Drive the inputs and watch the geometry redraw in real time. The preview deliberately stops short of the numbers: epicyclic gear ratios, sun, planet and ring tooth counts and carrier speeds all stay in the Android app.

Planetary gear demo

Enter sun and ring tooth counts to rebuild and animate the epicyclic train.

24 T
96 T
Planet count

Planet teeth follow the concentric constraint, and the drawn planet count drops back whenever the requested planets would not clear each other.

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What the planetary gear calculator works out

Planetary Gear Calculator is deliberately narrow: it solves one sizing problem completely, with the assumptions written down next to the result.

Gear ratio
for every configuration: ring fixed, carrier fixed or sun fixed.
Planet tooth count
from the concentric condition, so the three members actually mesh.
Member speeds
sun, carrier and ring, including the sign that tells you the direction.
Assembly feasibility
whether the requested planets can be equally spaced without clashing.

Typical jobs

100% offline

Planetary Gear Calculator for Android

The Android app gives the numerical ratio for each fixed member, the planet tooth count, the member speeds for a given input RPM and the assembly checks, offline. No account, no sign-in, no data connection.

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