Planetary Gear Set (12T Sun, 9T Planets, 30T Ring)

This model is a planetary gear system designed for learning and experimentation.

It demonstrates the mechanics of an epicyclic gear train with the following parameters:

Sun gear: 12 teeth

Planet gears: 9 teeth each

Ring gear: 30 teeth

Module: 2.083 mm

Pitch diameter (sun): 25 mm

Pressure angle: 20°

Backlash: 0.05 mm

Gear Ratio Calculation:

Planetary gear ratio formula:

Ratio = 1 + (N_ring / N_sun)

Then:

Ratio = 1 + (30 / 12) Ratio = 1 + 2.5 Ratio = 3.5 : 1

This means the carrier rotates at 1/3.5 of the sun gear speed when the ring is fixed.

Perfect for students, hobbyists, and engineers interested in gear mechanics and motion transfer.
👉 View the design on Onshape:
Onshape Project Link