Free-piston cylinder liner Ø30 × 120 and Ø40 × 160 — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/free-piston-cylinder-liner/  (CC BY 4.0)
Basis: Bore 30 / 40, length 4 × bore, 3 mm wall
Catalog version: 2026-10-20

Sizes: see table below
- The bore that the displacer and power piston share in the beta free-piston core: Ø30 × 120 (Ø36 outside) or Ø40 × 160 (Ø46 outside), 3 mm wall.
- The displacer runs in it with a 0.5 mm radial gap, the power piston with 0.05 mm, and the stop bumpers fit its bore (fit: press).

file  bore  outside  length  wall
cylinder-liner-30x120  30  36  120  3
cylinder-liner-40x160  40  46  160  3

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- NASA (NTRS, public domain): Free-piston Stirling engine design and analysis (RE-1000 test results) (1984) — PDF — US Government work, public domain — https://ntrs.nasa.gov/search?q=19840017543
- NASA (NTRS, public domain): Dynamics of free-piston Stirling engines (1987) — PDF — US Government work, public domain — https://ntrs.nasa.gov/search?q=19870011457
- Wikipedia: Free-piston engine — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Free-piston_engine
- Wikipedia: Beale number — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Beale_number
- Ohio University: Stirling cycle machine analysis (Urieli), free online — web — Author's site — https://www.ohio.edu/mechanical/stirling/
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 2 parts): https://xemstudio.com/files/hardware/free-piston-cylinder-liner/index.json
API: https://xemstudio.com/api/geometry?object=free-piston-cylinder-liner