# Lever with two pawls driving a ratchet on both strokes

> How can a lever drive a ratchet on both its strokes?

- Category: Mechanisms › Intermittent motion
- Kind: Hardware
- Basis: Xem Studio design following Brown No. 206 (1868)
- Page: https://xemstudio.com/objects/double-pawl-lever-ratchet-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=double-pawl-lever-ratchet-mechanism · Plain text: https://xemstudio.com/objects/double-pawl-lever-ratchet-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 lever rocks on a fulcrum beside the ratchet wheel and carries two pawls, pinned one above and one below the fulcrum. Swinging the handle one way, the upper pawl pivot moves toward the wheel and its pawl pushes a tooth; swinging it back, the lower pivot moves toward the wheel and the lower pawl pushes another tooth, while the first slides back over the teeth. The wheel is driven the same way on both strokes, so the motion is nearly continuous.
- Catalog Ø40, 24-tooth ratchet; both pawls drawn with their end faces lying on the steep faces of two teeth (face contact, no overlap) at the same instant.
- Brown's No. 206 (lever with rising and falling pawls giving a nearly continuous rotary motion to a ratchet wheel).
- Parts (each has its own page): ratchet-and-pawl, lever-pawl-24t-d40-upper, lever-pawl-24t-d40-lower, double-pawl-lever-fulcrum-handle-80, dowel-pins-metric.
- Brown's movement No. 206 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

## Sizes

| parameter | value |
|---|---|
| ratchet | 24 T, Ø40 |
| pawls | 2, face contact |
| drive | both strokes, same direction |

## 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. 206: figure, his text and an animation](https://507movements.com/mm_206.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/double-pawl-lever-ratchet-mechanism/index.json · license: https://xemstudio.com/files/hardware/double-pawl-lever-ratchet-mechanism/LICENSE.md

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

## Questions

**How can a lever drive a ratchet on both its strokes?**

A lever rocks on a fulcrum beside the ratchet wheel and carries two pawls, pinned one above and one below the fulcrum. Swinging the handle one way, the upper pawl pivot moves toward the wheel and its pawl pushes a tooth; swinging it back, the lower pivot moves toward the wheel and the lower pawl pushes another tooth, while the first slides back over the teeth. The wheel is driven the same way on both strokes, so the motion is nearly continuous.

## Fits with

- [Ratchet wheels Ø40 with 12, 24 and 36 teeth](https://xemstudio.com/objects/ratchet-wheels/)
- [Pawl for the 24-tooth Ø40 ratchet, pivot to nose 30.89 mm](https://xemstudio.com/objects/lever-pawl-24t-d40-upper/)
- [Pawl for the 24-tooth Ø40 ratchet, pivot to nose 26.87 mm](https://xemstudio.com/objects/lever-pawl-24t-d40-lower/)
- [Double-pawl lever: fulcrum, two pawl pivots and an 80 mm handle](https://xemstudio.com/objects/double-pawl-lever-fulcrum-handle-80/)
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/)