Cardboard Planetary Epicyclic Gearbox Speed Reducer

60 mins Ages 9-14 Indoor

An engaging, screen-free learning activity that builds real-world creativity and critical thinking for kids aged 9 to 14.

Materials Needed

  • • Heavy corrugated cardboard sheets (2 panels)
  • • Wooden craft skewers and brass split brads (6 units)
  • • Gear tooth stencil templates and glue stick (1 set)
  • • Precision craft utility knife (adult use) (1 unit)

Pro Tips

  • → A planetary gearbox consists of a central sun gear, three revolving planet gears on a carrier arm, and an outer ring gear.
  • → When the outer ring is fixed and the sun gear turns fast, the planet carrier rotates slowly with immense mechanical torque.
  • → Let your teen test holding different gears stationary to observe how the gear ratio dynamically shifts.

Safety First

Adult supervision required when cutting gear teeth with craft knife.

How was this activity?

Your anonymous feedback helps us recommend better activities.

Step-by-Step Instructions

1

Step 1

Glue gear templates onto thick corrugated cardboard and carefully cut out the sun gear, 3 planet gears, and outer ring.

2

Step 2

Mount the three planet gears onto a triangular cardboard carrier plate using wooden skewer pivot pins.

3

Step 3

Mesh the sun gear at the center and enclose the assembly within the outer ring gear chassis.

4

Step 4

Turn the sun gear crank while holding the outer ring gear stationary, observing the high-torque slow rotation of the planet carrier.

What they are learning

Epicyclic planetary gear kinematics (Sun, Planet, Ring gear) Mechanical torque multiplication & speed reduction Automotive automatic transmission principles