This is a planetary gear box. It has 3 sets of gears. Sun gear, planet gear, and ring gear.

The sun gear has 10 teeth, planet gear has 20 teeth, and ring gear has 50 teeth.

The first set of the gears has a reduction of 1:6. Add another set which is 1:6, total it has a reduction of 1:36.

With the sun being the input, planet carrier being the output, the ring gear is the fixed.

For ever 36 times the sun gear rotate, the planet carrier rotate 1 times. This has increase of torque but reduce in speed. Which is REALLY COOL!

Parts that's needed:

• Sun Gear Set 1
• Sun Gear Set 2
• 6 Planet gears
• Ring Gear Set 1
• Ring Gear Set 2
• Planet Carrier Set 1
• Planet Carrier Set 2
• Output shaft
• 6 C Clamps
• Motor holder (Motor used here)
• 1 10x14x4mm Bearing (Here)
• 1 3x6x2mm Bearing (Here)

I explain everything here in this video: