# Ross yoke rocking link, 40 mm

> How long is the rocking link on a Ross yoke?

- Category: Stirling engines › Drives & mechanisms
- Kind: Hardware
- Basis: Solved Ross linkage: rocking link 40 from the frame pivot at (−40, 20) to the yoke's top-middle pin
- Page: https://xemstudio.com/objects/ross-rocking-link/ · JSON: https://xemstudio.com/api/geometry?object=ross-rocking-link · Plain text: https://xemstudio.com/objects/ross-rocking-link/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

**Exact dimensions.** Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part.

## Notes

- The link that steadies the Ross yoke: 40 mm between Ø3 ends (fit: run), 48 × 8 × 5.
- One end turns on the Ø3 × 20 pin in the frame post, the other on the pin in the yoke's top-middle; it runs in the front plane, outside the con-rods.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| link and con-rod ends | Ø3 | Ø3 pins (turn on them) | run | rocking-link-* |

## Sizes

| parameter | value |
|---|---|
| centres | 40 |
| outline | 48 × 8 × 5 |
| holes | 2 × Ø3 (run) |

## Where the files are

- Wikipedia: [Ross yoke](https://en.wikipedia.org/wiki/Ross_yoke) — web — CC BY-SA 4.0 (text)
- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

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

Index: https://xemstudio.com/files/hardware/ross-rocking-link/index.json

- rocking-link-40: [STEP](https://xemstudio.com/files/hardware/ross-yoke-kit/rocking-link-40.step) · [STL](https://xemstudio.com/files/hardware/ross-yoke-kit/rocking-link-40.stl) — rocking link 40 mm, Ø3 ends (pins turn in them): frame post to the yoke's top-middle pin, in the front plane

## How it fits

### Connects to
- [Ross yoke a = h = 20 for two parallel syringes](https://xemstudio.com/objects/ross-yoke/): top-middle Ø3 pin
- [Ross yoke alpha frame for two 10 mL syringes](https://xemstudio.com/objects/ross-yoke-frame/): Ø3 pin in the post

### Also needed
- [Crankshafts Ø3, Ø5 and Ø8 with full-length D-flat](https://xemstudio.com/objects/stirling-crankshafts/): Ø3 × 20 pins, spacers

## Questions

**What does the rocking link on a Ross yoke do?**

It holds the yoke's top-middle on an arc about the frame post, so the yoke rocks instead of swinging freely on the crank pin.

**Where does the rocking link pivot?**

On a Ø3 pin in the frame post at (−40, 20) from the crank axis.

## Fits with

- [Ross yoke a = h = 20 for two parallel syringes](https://xemstudio.com/objects/ross-yoke/)
- [Ross yoke alpha frame for two 10 mL syringes](https://xemstudio.com/objects/ross-yoke-frame/)
- [Build list: Ross yoke alpha, two parallel 10 mL syringes](https://xemstudio.com/objects/list-ross-yoke-alpha/)