Xem Studiomeasured geometryLibrary › Mechanisms › Belt and friction drives ·
Conoid (curved cone) pulleys: varied speed with a belt of constant length
Why are the cones curved? · Hardware · basis: Xem Studio design following Brown No. 10 (1868)
Also called: conoid pulleys, curved speed cones, variable speed cone pulleys, poleas conoides, gewölbte Kegelscheiben
Exact dimensions. True size, with no printing tolerance added.
- sizes
- 5 in table
Notes
- Two straight cones head to tail keep r₁ + r₂ constant, which keeps a CROSSED belt the same length but not an open one: an open belt goes slack away from the middle. Curving the cones by the right amount makes the open-belt length exactly constant.
- Here Ø24–Ø56 × 64 conoids at 110 mm; at 20 mm along, Ø27.9 drives Ø51.9, ratio 0.54. The belt length 346.65 mm is the same at every position (straight cones of the same size lose -4.64 mm near the ends).
- Brown's No. 10 (cone pulleys of curved outline for gradually varying speed).
- Parts (each has its own page): conoid-pulley-24-56x64-bore8, flat-belt-10x1-5-conoid-pulleys-c110.
- Brown's movement No. 10 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.
Conoid (curved cone) pulleys: varied speed with a belt of constant… size chart
| parameter | value |
|---|---|
| pulleys | 2 × Ø24–Ø56 × 64 conoids, head to tail |
| centres | 110 mm |
| ratio range | 0.43 – 2.33 (approx.) |
| drawn at 20 mm | ratio 0.54 |
| belt | 10 × 1.5, 346.65 mm |
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 |
| 507movements.com | Brown's movement No. 10: figure, his text and an animation | web | Publisher's page; dimensions are facts |
Free files
★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json
| conoid-pulleys-mechanism-assembly | Assembled mechanism, all parts placed at one pose (STEP keeps each part separate) | STEP · STL |
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=conoid-pulleys-mechanism
Fits with
Questions
Why are the cones curved?
Two straight cones head to tail keep r₁ + r₂ constant, which keeps a CROSSED belt the same length but not an open one: an open belt goes slack away from the middle. Curving the cones by the right amount makes the open-belt length exactly constant.