{
 "version": "2026-10-20",
 "license": "Dimension sheets are written by Xem Studio from the cited sources and are free to use (CC BY 4.0, attribute 'Xem Studio'). Linked files belong to their publishers under the license shown; Xem Studio does not host them. 'license_verified: false' means the license shown is from memory or the publisher's page as last read and should be confirmed at the link before commercial use.",
 "slug": "stirling-walking-beam",
 "name": "Walking beam for a tri-clamp beam engine (arms 158.07 / 131.73)",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Stirling & thermoacoustic",
 "year": null,
 "question": "How do I build a walking beam for a vertical power cylinder?",
 "tags": [
  "beam",
  "walking beam",
  "linkage",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "walking beam stirling",
  "beam engine linkage"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/stirling-walking-beam/",
 "sheet_txt": "https://xemstudio.com/objects/stirling-walking-beam/sheet.txt",
 "sheet": {
  "basis": "Design values; 625 and dowel sizes from their standards",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A T-shaped beam on two 625 bearings on a Ø5 pivot pin in the post's cheeks. Arm A (158.62) carries a Ø6 pin for the 60 mm link from the piston rod's crosshead; arm B (132.18) a Ø5 pin for the 488.4 mm link down to the crank. The arm ratio 1.2 turns the crank's 30 mm throw into the piston's 36 mm stroke."
  ],
  "table": {
   "columns": [
    "feature",
    "value"
   ],
   "rows": [
    [
     "arm A",
     158.62
    ],
    [
     "arm B",
     132.18
    ],
    [
     "pivot",
     "Ø16 bore, two 625"
    ],
    [
     "swing",
     "±6.5°"
    ]
   ]
  }
 },
 "sheet_text": "Walking beam for a tri-clamp beam engine (arms 158.07 / 131.73) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/stirling-walking-beam/  (CC BY 4.0)\nBasis: Design values; 625 and dowel sizes from their standards\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A T-shaped beam on two 625 bearings on a Ø5 pivot pin in the post's cheeks. Arm A (158.62) carries a Ø6 pin for the 60 mm link from the piston rod's crosshead; arm B (132.18) a Ø5 pin for the 488.4 mm link down to the crank. The arm ratio 1.2 turns the crank's 30 mm throw into the piston's 36 mm stroke.\n\nfeature  value\narm A  158.62\narm B  132.18\npivot  Ø16 bore, two 625\nswing  ±6.5°\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/stirling-walking-beam/index.json\nAPI: https://xemstudio.com/api/geometry?object=stirling-walking-beam\n",
 "sources": [
  {
   "publisher": "Long Earth Society",
   "title": "Engine builds",
   "url": "https://longearthsociety.com/engineering/",
   "formats": [
    "web",
    "video"
   ],
   "license": "LES site",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "list-tri-clamp-walking-beam-gamma"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.",
 "mating": [
  {
   "feature": "pivot bore",
   "exact": "Ø16 × 10",
   "mates": "two 625 bearings",
   "fit": "press",
   "files": "all"
  },
  {
   "feature": "end A hole",
   "exact": "Ø6",
   "mates": "Ø6 dowel pin (link A)",
   "fit": "press",
   "files": "all"
  },
  {
   "feature": "end B hole",
   "exact": "Ø5",
   "mates": "Ø5 dowel pin (link B)",
   "fit": "press",
   "files": "all"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. Typical FDM: hole +0.0 to +0.1 mm on diameter.",
  "slide": "assembles by hand and is held by a grub, pinch or clamp: shaft in a hub, rod in a socket, spigot in a bore. Typical FDM: +0.2 mm.",
  "run": "turns or slides in use: pin in a link, rod through a guide. Typical FDM: +0.3 mm.",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. Typical FDM: +0.3 mm.",
  "clamp": "split part that closes on the mating part with screws: make it at size.",
  "designed": "a gap that is part of the design (piston fit option, displacer gap, air gap): do not change."
 },
 "faq": [
  {
   "q": "Why a beam?",
   "a": "It is the classic desk layout: the power cylinder stands up from the middle of the displacer cylinder and the beam brings its motion to the same crank as the displacer."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "walking-beam-158.07-131.73",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-walking-beam/walking-beam-158.07-131.73.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-walking-beam/walking-beam-158.07-131.73.stl",
   "note": "walking beam 10 thick: pivot boss Ø30 with an Ø16 bore (two 625), end A Ø6 press hole 158.62 from the pivot, end B Ø5 press hole 132.18 from it, bar 16 high, stem to 40 below the pivot"
  }
 ],
 "markdown": "https://xemstudio.com/objects/stirling-walking-beam/index.md"
}