Xem Studiomeasured geometryLibrary › Stirling engines › Free-piston ·
Piston stop bumper Ø30 and Ø40 × 6
What stops a free-piston Stirling piston from hitting the end of its cylinder? · Hardware · basis: OD = liner bore (fit: press); recess 0.6 × bore
Long Earth Society build part. The LES free-piston test bed: Ø40 core on flexures in a 2 in tri-clamp vessel. 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
- 2 in table
Notes
- An end stop for the free-piston core: Ø30 or Ø40 (the liner bore, fit: press) × 6 tall, a 2 mm closed face over a 4 mm deep recess of 0.6 × the bore (Ø18 / Ø24), with a 1 mm rounded edge.
- One at each end of the stroke; the stroke is kept to 85 % of the free travel between them. Over-stroke, when the alternator load drops, is the usual way a free-piston engine fails.
Sizes
| file | OD | height | recess | face |
|---|---|---|---|---|
| stop-bumper-30 | 30 | 6 | Ø18 × 4 | 2 |
| stop-bumper-40 | 40 | 6 | Ø24 × 4 | 2 |
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 |
|---|---|---|---|---|
| rod bores | Ø5 | Ø5 rod | slide | all |
| stop bumper OD | Ø30 / Ø40 | liner bore | press | stop-bumper-* |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| NASA (NTRS, public domain) | Free-piston Stirling engine design and analysis (RE-1000 test results) (1984) | US Government work, public domain | |
| NASA (NTRS, public domain) | Dynamics of free-piston Stirling engines (1987) | US Government work, public domain | |
| Wikipedia | Free-piston engine | web | CC BY-SA 4.0 (text) |
| Wikipedia | Beale number | web | CC BY-SA 4.0 (text) |
| Ohio University | Stirling cycle machine analysis (Urieli), free online | web | Author's site |
| Long Earth Society | Engine builds | web, video | LES site |
Free files
★ Free files 2 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json
| stop-bumper-30 | end-stop bumper Ø30 OD (= the Ø30 bore) × 6 | STEP · STL |
| stop-bumper-40 | end-stop bumper Ø40 OD (= the Ø40 bore) × 6 | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=piston-stop-bumper
How it fits
Goes in or on
Free-piston cylinder liner Ø30 × 120 and Ø40 × 160in the Ø30 / Ø40 boreConnects to
Free-piston Stirling power piston Ø29.9 × 30 and…at each end of its travelYou might also need
Questions
What stops a free-piston engine from over-stroking?
The alternator load first; bumpers at both ends of the stroke for when the load drops, with the stroke kept to 85 % of the free travel.
How big is the stop bumper for a 40 mm bore?
Ø40 × 6 with a Ø24 × 4 recess.