# One tooth turning a notched wheel one notch per turn, locked between (Geneva principle)

> How does a single tooth give a locked, step-by-step motion?

- Category: Mechanisms › Intermittent motion
- Kind: Hardware
- Basis: Xem Studio design following Brown No. 68 (1868)
- Page: https://xemstudio.com/objects/single-tooth-intermittent-wheel-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=single-tooth-intermittent-wheel-mechanism · Plain text: https://xemstudio.com/objects/single-tooth-intermittent-wheel-mechanism/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files Xem Studio Design License (free to use and sell from, not to redistribute as files: https://xemstudio.com/license/)
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- A driver with a single tooth (here a round pin) turns a wheel with notches: once per turn the tooth enters a notch and moves the wheel one division; for the rest of the turn the driver's plain rim sits in a concave arc of the wheel and locks it.
- Drawn with the catalog 6-station Geneva pair (R30 wheel, pin at R17.32, centres 34.64 mm = R / cos 30°): the pin is at the bottom of a slot at mid-index. The wheel moves 60° in 120° of driver rotation and stands locked for 240°.
- Brown's No. 68 (one tooth driving a notched wheel one notch per revolution, the blank part of the driver's rim locking it). Brown's Geneva stop (No. 212) is the watch-winding form.
- Parts (each has its own page): geneva-drive, dowel-pins-metric.
- Brown's movement No. 68 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

## Sizes

| parameter | value |
|---|---|
| stations | 6 |
| wheel | R30, 5 mm slots |
| pin radius | 17.32 mm |
| centres | 34.64 mm |
| motion / dwell | 120° / 240° of driver turn |

## Where the files are

- Henry T. Brown (1868, public domain): [Five Hundred and Seven Mechanical Movements — scan on archive.org](https://archive.org/details/fivehundredseven00browiala) — web — Publisher's page; dimensions are facts
- 507movements.com: [Brown's movement No. 68: figure, his text and an animation](https://507movements.com/mm_068.html) — web — Publisher's page; dimensions are facts

## Free STEP/STL (1 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/single-tooth-intermittent-wheel-mechanism/index.json · license: https://xemstudio.com/files/hardware/single-tooth-intermittent-wheel-mechanism/LICENSE.md

- single-tooth-intermittent-wheel-mechanism-assembly: [STEP](https://xemstudio.com/files/hardware/single-tooth-intermittent-wheel-mechanism/single-tooth-intermittent-wheel-mechanism-assembly.step) · [STL](https://xemstudio.com/files/hardware/single-tooth-intermittent-wheel-mechanism/single-tooth-intermittent-wheel-mechanism-assembly.stl) — Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)

## Questions

**How does a single tooth give a locked, step-by-step motion?**

A driver with a single tooth (here a round pin) turns a wheel with notches: once per turn the tooth enters a notch and moves the wheel one division; for the rest of the turn the driver's plain rim sits in a concave arc of the wheel and locks it.

## Fits with

- [Geneva drive: 4 and 6 station wheels, R30, with drive discs](https://xemstudio.com/objects/geneva-drive/)
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/)