Tri-clamp crank head: ISO 2852 cap with Ø3 rod bore and two 623 towers, 1.5, 2 and 3 in — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tri-clamp-crank-head/  (CC BY 4.0)
Basis: ISO 2852 cap face; Ø3 run bore for the displacer rod; two 623 bearing pockets (Ø10) on a Ø3 crank axis 30 mm above the face
Catalog version: 2026-10-20

Sizes: see table below
- An ISO 2852 end cap that carries both the displacer rod and a small crankshaft, so the drive sits right on the cylinder.
- On centre: a Ø18 × 9 boss with a Ø3 bore straight through for the Ø3 displacer rod (run fit); the bore is the rod guide and the clearance seal.
- Two towers 10 × 14 × 28 mm stand on the back of the 6 mm cap, centred ±(C3/2 − 11) from the axis (±14.25 / ±21.0 / ±34.5 mm for 1.5 / 2 / 3 in), each with a Ø10 pocket for a 623 bearing; the Ø3 crankshaft axis is 30 mm above the face, 24 mm above the cap's back.
- The overall height is 34 mm; flange Ø50.5 / 64.0 / 91.0.

size_in  flange_od_mm  rod_bore_mm  tower_centres_mm  bearing  crank_axis_above_face_mm
1.5  50.5  3  28.5  623 (Ø10)  30
2  64.0  3  42.0  623 (Ø10)  30
3  91.0  3  69.0  623 (Ø10)  30

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Long Earth Society: Tri-clamp Stirling engine builds — web, video — LES site — https://longearthsociety.com/engineering/
- James R. Senft: An Introduction to Low Temperature Differential Stirling Engines (displacer and gap design) — book — Moriya Press [verify license at link] — https://www.stirlingengine.com/
- Wikipedia: Stirling engine — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Stirling_engine

Free files (CC BY 4.0, Xem Studio; STEP + STL, 3 parts): https://xemstudio.com/files/hardware/tri-clamp-crank-head/index.json
API: https://xemstudio.com/api/geometry?object=tri-clamp-crank-head