# Toggle (knee-lever) press mechanism

> How much force does a toggle press give?

- Category: Mechanisms › Linkages
- Kind: Hardware
- Basis: Xem Studio drawing; classic mechanism (Brown No. 164)
- Page: https://xemstudio.com/objects/toggle-press-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=toggle-press-mechanism · Plain text: https://xemstudio.com/objects/toggle-press-mechanism/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- 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

- Two equal links in line with the output, bent slightly at the knee. A side force F at the knee gives an end force F / (2·tan θ), θ = each link's angle off the straight line.
- At θ = 15° the gain is 1.87×; it rises without limit as the links straighten (θ → 0), which is why presses, clamps and stone crushers use it.
- The stroke shrinks as the force grows: the end moves 2L(1 − cos θ) while straightening.
- Parts (each has its own page): toggle-links-50, crosshead-8mm, crosshead-guide-8mm, pins-3mm. Brown's movement No. 164 shows it (1868).

## Sizes

| parameter | value |
|---|---|
| link centres L | 50 mm |
| angle θ (drawn) | 15° |
| force gain at θ | 1.87× |

## 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

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/toggle-press-mechanism/index.json

- toggle-press-mechanism-assembly: [STEP](https://xemstudio.com/files/hardware/toggle-press-mechanism/toggle-press-mechanism-assembly.step) · [STL](https://xemstudio.com/files/hardware/toggle-press-mechanism/toggle-press-mechanism-assembly.stl) — Assembled mechanism, all parts placed (STEP keeps each part separate)

## Questions

**How much force does a toggle press give?**

Two equal links in line with the output, bent slightly at the knee. A side force F at the knee gives an end force F / (2·tan θ), θ = each link's angle off the straight line.

## Fits with

- [Toggle links, 50 mm centres (pair)](https://xemstudio.com/objects/toggle-links-50/)
- [Crosshead Ø8 × 24 for a Ø3 piston rod](https://xemstudio.com/objects/crosshead-8mm/)
- [Crosshead guide, Ø8 bore × 30](https://xemstudio.com/objects/crosshead-guide-8mm/)
- [Crank and wrist pins Ø3 × 12, 16, 19, 20 and 23](https://xemstudio.com/objects/pins-3mm/)