# Plate cam with roller follower (cycloidal rise)

> How does a plate cam with a roller follower work?

- Category: Mechanisms › Cams
- Kind: Hardware
- Basis: Xem Studio design following Brown No. 138 (1868)
- Page: https://xemstudio.com/objects/plate-cam-roller-follower-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=plate-cam-roller-follower-mechanism · Plain text: https://xemstudio.com/objects/plate-cam-roller-follower-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

- A disc cam turning on its shaft lifts a roller follower that slides in a straight guide: the profile is drawn from the displacement law — here cycloidal rise of 12 mm over 120°, dwell, return, dwell.
- Roller: rolling contact, low wear; the cam is the pitch curve offset by the roller radius (5 mm). Cycloidal motion has zero acceleration at both ends of the rise.
- Drawn at 60° of cam rotation (mid-rise, lift 6 mm) with the follower touching the profile; follower guide 30 × 16 block. Brown's No. 138.
- Parts (each has its own page): plate-cam-cycloidal-roller-r20-h12, roller-follower-fork-rod-8, roller-follower-10, follower-guide-block-8.
- Brown's movement No. 138 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

## Sizes

| parameter | value |
|---|---|
| base circle | R20 |
| rise | 12 mm / 120° |
| law | cycloidal |
| follower | roller |
| pose | 60°, lift 6 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. 138: figure, his text and an animation](https://507movements.com/mm_138.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/plate-cam-roller-follower-mechanism/index.json

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

## Questions

**How does a plate cam with a roller follower work?**

A disc cam turning on its shaft lifts a roller follower that slides in a straight guide: the profile is drawn from the displacement law — here cycloidal rise of 12 mm over 120°, dwell, return, dwell.

## Fits with

- [Plate cam, cycloidal rise 12 mm, base circle R20, for a roller follower](https://xemstudio.com/objects/plate-cam-cycloidal-roller-r20-h12/)
- [Roller-follower fork rod, 8 × 6 mm, for a Ø10 roller on a Ø3 pin](https://xemstudio.com/objects/roller-follower-fork-rod-8/)
- [Roller follower Ø10 on a Ø3 pin](https://xemstudio.com/objects/roller-follower-10/)
- [Follower guide block 30 × 16 × 6 for an 8 mm wide follower](https://xemstudio.com/objects/follower-guide-block-8/)