Differential Gear Model

A working model of a car's differential on an 80 × 80 mm base. The crown gear is the input; the two output shafts can turn at different speeds.

It answers a good question: when a car turns, the outer wheel travels further than the inner one, so how can one engine drive both? Students turn the input and hold one output to see the other speed up.

Design by osamutake on Printables, shared under CC BY 4.0. The files and photos are the designer's, unchanged.

1. Print the "printable" file; the "assembled" one is for viewing.
2. Assemble and turn the input with both outputs free, then with one held.
3. Students explain what happens to a car's wheels in a corner, and why a car can get stuck when one wheel is on ice.