How do pulleys and belts work?

Wheels joined by a belt pass motion over a distance. A belt wrapped around two pulleys carries turning from one axle to another far away. Unlike gears, belts can slip when overloaded, which protects the motor — a built-in safety clutch!

Try Belt-Drive Buggy for free

Gearbox & Drivetrain Cars booklet pack: 30 PDF booklets for $5.99. Instructions only; individual booklets remain free.

Explore the printable pack

Try it yourself

Hold the output pulley still while turning the input. Feel it slip?

Build it: the build that teach pulleys & belts

  • 🪢 Belt-Drive Buggy: No gears touching: a loop carries the power from the motor down to the wheels. (level 3 of 5, about 35 minutes, 11 steps)

In the classroom

Common engineering questions

How can I try pulleys & belts at home?

Hold the output pulley still while turning the input. Feel it slip?

Which builds teach pulleys & belts?

One MightyCog build teaches it: Belt-Drive Buggy. Start with Belt-Drive Buggy: 11 steps, about 35 minutes.

Ideas that go with it