Rocker beam 60 / 80 / 100 mm on a 623 pivot — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/rocker-beam/  (CC BY 4.0)
Basis: Centre pivot on a 623 bearing (Ø10 pocket, fit: press); Ø3 end holes (fit: run) at ±L/2
Catalog version: 2026-10-20

Sizes: see table below
- The walking beam of a beam-driven gamma: one end to the crank's con-rod, the other to the displacer rod, pivoting in the middle.
- A 12 wide × 6 thick bar L + 12 long (72 / 92 / 112) with Ø3 holes at ±L/2 (fit: run) and a Ø10 pocket on centre for a 623 bearing (fit: press).
- With equal arms the ratio is 1:1: the displacer stroke equals the crank stroke.

file  pin centres  length  section  pivot  end holes
rocker-beam-60  60  72  12 × 6  Ø10 (623)  Ø3
rocker-beam-80  80  92  12 × 6  Ø10 (623)  Ø3
rocker-beam-100  100  112  12 × 6  Ø10 (623)  Ø3

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Wikipedia: Beam engine — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Beam_engine
- Wikipedia: Stirling engine — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Stirling_engine
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

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