# Belt drive between shafts at right angles with two guide pulleys

> How do guide pulleys carry a belt round a right angle?

- Category: Mechanisms › Belt and friction drives
- Kind: Hardware
- Basis: Xem Studio design following Brown No. 3 (1868)
- Page: https://xemstudio.com/objects/guide-pulley-right-angle-belt-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=guide-pulley-right-angle-belt-mechanism · Plain text: https://xemstudio.com/objects/guide-pulley-right-angle-belt-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

- Two pulleys on shafts at right angles, joined by one belt led over two guide pulleys on a single inclined shaft. Each strand lies in the mid-planes of both pulleys it joins, so the belt runs in either direction without leaving the faces.
- Here two Ø40 pulleys sit 80 mm apart on the common perpendicular, their belt lines all parallel; the guides (Ø28.28 = 20√2) are 100 mm beyond, on a shaft at 45° to both. Each strand twists 45°; belt 12 × 1.5, inside length 774.52 mm.
- Brown's No. 3 (guide pulleys carrying the belt between shafts at right angles); No. 4 does it with the belt alone, working one way only.
- Parts (each has its own page): plain-flat-pulley-40x12, plain-flat-pulley-28-28x12-bore6, flat-belt-12x1-5-right-angle-guide-drive, dowel-pins-metric.
- Brown's movement No. 3 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

## Sizes

| parameter | value |
|---|---|
| pulleys | 2 × Ø40 × 12, shafts at 90° |
| guide pulleys | 2 × Ø28.28 on one shaft at 45° |
| ratio | 1 : 1 |
| belt | 12 × 1.5, 774.52 mm |

## 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. 3: figure, his text and an animation](https://507movements.com/mm_003.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/guide-pulley-right-angle-belt-mechanism/index.json · license: https://xemstudio.com/files/hardware/guide-pulley-right-angle-belt-mechanism/LICENSE.md

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

## Questions

**How do guide pulleys carry a belt round a right angle?**

Two pulleys on shafts at right angles, joined by one belt led over two guide pulleys on a single inclined shaft. Each strand lies in the mid-planes of both pulleys it joins, so the belt runs in either direction without leaving the faces.

## Fits with

- [Plain flat-belt pulley Ø40 × 12 face, Ø8 bore (no flanges)](https://xemstudio.com/objects/plain-flat-pulley-40x12/)
- [Guide pulley Ø28.28 × 12, Ø6 bore (plain face)](https://xemstudio.com/objects/plain-flat-pulley-28-28x12-bore6/)
- [Flat belt 12 × 1.5 for the right-angle guide-pulley drive (loop drawn on the pulleys)](https://xemstudio.com/objects/flat-belt-12x1-5-right-angle-guide-drive/)
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/)