Xem Studiomeasured geometryLibrary › Stirling engines › Drives & mechanisms ·
Ratchet wheels Ø40 with 12, 24 and 36 teeth
How are the teeth of a ratchet wheel shaped? · Hardware · basis: Sawtooth wheel: tips at R20, roots at R17 (3 mm deep), each tooth rising over 85 % of the pitch and dropping over 15 %
Long Earth Society build part. Anti-reverse for the LES flywheel generators; same mechanism as a reel's clicker. The engines
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. Mating features
- sizes
- 3 in table
Notes
- A Ø40 × 6 wheel with a Ø5 bore and 12, 24 or 36 sawtooth teeth 3 mm deep (tips on R20, roots on R17).
- Each tooth rises from root to tip over 85 % of the pitch (the back) and drops back over 15 % (the face the pawl locks against).
- Steps: 12 teeth 30°, 24 teeth 15°, 36 teeth 10°. Fewer teeth are larger and stronger.
- A one-way drive: anti-reverse on a reel, a hand-wound starter, or between a Stirling flywheel and a generator so the generator never back-drives the engine.
Sizes
| file | teeth | step | tip Ø | root Ø | thickness | bore |
|---|---|---|---|---|---|---|
| ratchet-12t-d40 | 12 | 30° | 40 | 34 | 6 | 5 |
| ratchet-24t-d40 | 24 | 15° | 40 | 34 | 6 | 5 |
| ratchet-36t-d40 | 36 | 10° | 40 | 34 | 6 | 5 |
Mating features
Drawn at the exact size. Open press, slide, run and socket features by your process's clearance; leave designed gaps and clamp fits as drawn.
| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| wheel bore | Ø5 | Ø5 shaft | slide | ratchet-* |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| Wikipedia | Ratchet (device) | web | CC BY-SA 4.0 (text) |
| Wikipedia | Pawl | web | CC BY-SA 4.0 (text) |
| Long Earth Society | Engine builds that use these parts (videos and write-ups) | web, video | LES site |
Free files
★ Free files 3 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json
| ratchet-12t-d40 | ratchet wheel Ø40 × 6, 12 teeth 3 mm deep, Ø5 bore | STEP · STL |
| ratchet-24t-d40 | ratchet wheel Ø40 × 6, 24 teeth 3 mm deep, Ø5 bore | STEP · STL |
| ratchet-36t-d40 | ratchet wheel Ø40 × 6, 36 teeth 3 mm deep, Ø5 bore | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=ratchet-wheels
How it fits
Goes in or on
Metric shafts Ø3 to Ø10 with D-flats and clip…Ø5 shaft in the boreConnects to
Pawl 24 mm with a Ø3 pivot for the Ø40 ratchet…pawl tip against the tooth faceAlso needed
Torsion spring wire Ø0.8, OD 8, 6 coilsholds the pawl on the teethYou might also need
Questions
How many teeth should a ratchet have?
12 teeth (30° steps) are the largest and strongest; 24 or 36 give 15° or 10° steps.
How deep are the teeth?
3 mm, from R20 at the tips to R17 at the roots.