What does a clutch do in a gearbox?
A part that connects or disconnects a gear from its axle. A clutch gear has a round hole, so it spins freely on its axle — it is "disconnected". A driving ring slides along the axle and locks onto the gear's teeth, connecting it. Sliding the ring left or right picks which gear drives.
Try Clutch-Gear 2-Speed Car for freeGearbox & Drivetrain Cars booklet pack: 30 PDF booklets for $5.99. Instructions only; individual booklets remain free.
Explore the printable packTry it yourself
Spin a clutch gear on an axle by itself: it slips! Now push the driving ring into it and try again.
Build it: 4 builds that teach clutch & driving ring
- ⚙️ Clutch-Gear 2-Speed Car: Push the gear lever and a driving ring grabs a different gear: 1st climbs, 2nd races! (level 3 of 5, about 45 minutes, 18 steps)
- ↩️ Reverse-Gear Truck: The motor only spins one way — the gear lever decides forwards or backwards! (level 4 of 5, about 55 minutes, 18 steps)
- 🔄 Reverse-to-Turn Car: Only one motor — but it can still turn! Drive backwards and the wheels swing round. (level 4 of 5, about 50 minutes, 24 steps)
- 🏁 Three-Speed Car: Two little gearboxes in a row make a big one: crawl, cruise or fly! (level 4 of 5, about 60 minutes, 20 steps)
In the classroom
- M3 Gearboxes: How Cars Go (Engineers, Advanced)
Common engineering questions
How can I try clutch & driving ring at home?
Spin a clutch gear on an axle by itself: it slips! Now push the driving ring into it and try again.
Which builds teach clutch & driving ring?
4 MightyCog builds teach it: Clutch-Gear 2-Speed Car, Reverse-Gear Truck, Reverse-to-Turn Car and Three-Speed Car. Start with Clutch-Gear 2-Speed Car: 18 steps, about 45 minutes.