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Universal (Hooke / Cardan) joint
Why does a universal joint not turn at constant speed? · Hardware · basis: Xem Studio drawing; classic mechanism (Brown No. 50)
Also called: universal joint, cardan joint, hooke joint, u joint speed, junta cardán, junta cardan, Kardangelenk
Exact dimensions. True size, with no printing tolerance added.
- sizes
- 2 in table
Notes
- Two yokes at 90° on a cross: shafts at an angle β turn together, but the output speed swings: ω₂/ω₁ = cos β / (1 − sin²β·cos²θ), between cos β and 1/cos β twice per turn.
- Two joints in phase with equal angles (a double Cardan or a drive shaft with both yokes aligned) cancel the swing.
- Brown shows two forms (Nos. 50 and 51). The 5 mm printable joint is its own page.
- Parts (each has its own page): universal-joint-5mm, clevis-pins. Brown's movement No. 50 shows it (1868).
Universal (Hooke / Cardan) joint size chart
| parameter | value |
|---|---|
| angle β (max, printable joint) | ≈30° |
| speed swing at 30° | 0.866 – 1.155 |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| Henry T. Brown (1868, public domain) | Five Hundred and Seven Mechanical Movements — scan on archive.org | web | Publisher's page; dimensions are facts |
Xem scan
Not needed Published standard; the sheet is the geometry.
https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.Plain text: sheet.txt · JSON: /api/geometry?object=universal-joint-mechanism
Fits with
Questions
Why does a universal joint not turn at constant speed?
Two yokes at 90° on a cross: shafts at an angle β turn together, but the output speed swings: ω₂/ω₁ = cos β / (1 − sin²β·cos²θ), between cos β and 1/cos β twice per turn.