How does a ratchet and pawl work?
Lets something turn one way but not the other. A ratchet is a toothed wheel with a little catch called a pawl. Turning one way, the pawl clicks over the teeth. Turning back, it jams in a tooth and stops. Winches and car jacks use it so loads do not fall back down.
Try Spring Catapult for freeComplete MightyCog booklet collection: 82 PDF booklets for $12.99. Instructions only; individual booklets remain free.
Explore the printable packTry it yourself
Lift the load, let go of the crank — does it stay up? Now lift the pawl!
Build it: 3 builds that teach ratchet & pawl
- 🎯 Spring Catapult: Cock the arm, click the trigger, FIRE! A spring flings the ammo across the room. (level 2 of 5, about 25 minutes, 14 steps)
- 🚀 Launch-Lock Racer: Wind it up, and a little catch holds the spring tight until YOU press the launch button! (level 3 of 5, about 40 minutes, 21 steps)
- 🛠️ Ratchet Car Jack: Crank the handle — click, click, click — and lift a toy car. Let go and it stays up! (level 3 of 5, about 35 minutes, 15 steps)
In the classroom
- M1 Force, Mass & Motion (Engineers, Advanced)
Common engineering questions
How can I try ratchet & pawl at home?
Lift the load, let go of the crank — does it stay up? Now lift the pawl!
Which builds teach ratchet & pawl?
3 MightyCog builds teach it: Spring Catapult, Launch-Lock Racer and Ratchet Car Jack. Start with Spring Catapult: 14 steps, about 25 minutes.