{
 "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": "ross-rocking-link",
 "name": "Ross yoke rocking link, 40 mm",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Drives & mechanisms",
 "year": null,
 "question": "How long is the rocking link on a Ross yoke?",
 "tags": [
  "ross yoke",
  "link",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "ross yoke rocking link",
  "40 mm link 3 mm holes",
  "ross yoke link length"
 ],
 "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/ross-rocking-link/",
 "sheet_txt": "https://xemstudio.com/objects/ross-rocking-link/sheet.txt",
 "sheet": {
  "basis": "Solved Ross linkage: rocking link 40 from the frame pivot at (−40, 20) to the yoke's top-middle pin",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "The link that steadies the Ross yoke: 40 mm between Ø3 ends (fit: run), 48 × 8 × 5.",
   "One end turns on the Ø3 × 20 pin in the frame post, the other on the pin in the yoke's top-middle; it runs in the front plane, outside the con-rods."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "centres",
     40
    ],
    [
     "outline",
     "48 × 8 × 5"
    ],
    [
     "holes",
     "2 × Ø3 (run)"
    ]
   ]
  }
 },
 "sheet_text": "Ross yoke rocking link, 40 mm — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/ross-rocking-link/  (CC BY 4.0)\nBasis: Solved Ross linkage: rocking link 40 from the frame pivot at (−40, 20) to the yoke's top-middle pin\nCatalog version: 2026-10-20\n\nSizes: see table below\n- The link that steadies the Ross yoke: 40 mm between Ø3 ends (fit: run), 48 × 8 × 5.\n- One end turns on the Ø3 × 20 pin in the frame post, the other on the pin in the yoke's top-middle; it runs in the front plane, outside the con-rods.\n\nparameter  value\ncentres  40\noutline  48 × 8 × 5\nholes  2 × Ø3 (run)\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Ross yoke — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Ross_yoke\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/ross-rocking-link/index.json\nAPI: https://xemstudio.com/api/geometry?object=ross-rocking-link\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Ross yoke",
   "url": "https://en.wikipedia.org/wiki/Ross_yoke",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "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": [
  "ross-yoke",
  "ross-yoke-frame",
  "list-ross-yoke-alpha"
 ],
 "fits": [
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "ross-yoke",
     "why": "top-middle Ø3 pin"
    },
    {
     "slug": "ross-yoke-frame",
     "why": "Ø3 pin in the post"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "stirling-crankshafts",
     "why": "Ø3 × 20 pins, spacers"
    }
   ]
  }
 ],
 "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": "link and con-rod ends",
   "exact": "Ø3",
   "mates": "Ø3 pins (turn on them)",
   "fit": "run",
   "files": "rocking-link-"
  }
 ],
 "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": "What does the rocking link on a Ross yoke do?",
   "a": "It holds the yoke's top-middle on an arc about the frame post, so the yoke rocks instead of swinging freely on the crank pin."
  },
  {
   "q": "Where does the rocking link pivot?",
   "a": "On a Ø3 pin in the frame post at (−40, 20) from the crank axis."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "rocking-link-40",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/ross-yoke-kit/rocking-link-40.step",
   "stl": "https://xemstudio.com/files/hardware/ross-yoke-kit/rocking-link-40.stl",
   "note": "rocking link 40 mm, Ø3 ends (pins turn in them): frame post to the yoke's top-middle pin, in the front plane"
  }
 ],
 "markdown": "https://xemstudio.com/objects/ross-rocking-link/index.md"
}