# Grooved (wedge) friction gearing, 30 : 60

> Why are friction wheels grooved?

- Category: Mechanisms › Belt and friction drives
- Kind: Hardware
- Basis: Xem Studio design following Brown No. 45 (1868)
- Page: https://xemstudio.com/objects/grooved-friction-wheels-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=grooved-friction-wheels-mechanism · Plain text: https://xemstudio.com/objects/grooved-friction-wheels-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

- Ridges on one wheel wedge into matching V-grooves on the other: pressed together with force F, the normal force on the flanks is F / sin(α/2), so with 67.38° grooves the grip is about 1.8 times that of plain wheels at the same pressure.
- Ratio by pitch diameters, 60/30 = 2 : 1, centres 45 mm; the two profiles are exact complements on the line of centres (touching flanks, no overlap).
- Brown's No. 45 (friction gearing with grooves, shown in section).
- Parts (each has its own page): grooved-friction-wheel-30, grooved-friction-wheel-60.
- Brown's movement No. 45 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

## Sizes

| parameter | value |
|---|---|
| wheels | pitch Ø30 and Ø60 × 16 |
| grooves | 4 mm pitch, 67.38° |
| centres | 45 mm |
| grip gain | ≈ 1.8× |

## 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. 45: figure, his text and an animation](https://507movements.com/mm_045.html) — web — Publisher's page; dimensions are facts

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

Index: https://xemstudio.com/files/hardware/grooved-friction-wheels-mechanism/index.json

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

## Questions

**Why are friction wheels grooved?**

Ridges on one wheel wedge into matching V-grooves on the other: pressed together with force F, the normal force on the flanks is F / sin(α/2), so with 67.38° grooves the grip is about 1.8 times that of plain wheels at the same pressure.

## Fits with

- [Grooved friction wheel, pitch Ø30, 4 mm V-grooves × 16 wide](https://xemstudio.com/objects/grooved-friction-wheel-30/)
- [Grooved friction wheel, pitch Ø60, 4 mm V-grooves × 16 wide](https://xemstudio.com/objects/grooved-friction-wheel-60/)