{
 "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": "ratchet-pawl",
 "name": "Pawl 24 mm with a Ø3 pivot for the Ø40 ratchet wheels",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Drives & mechanisms",
 "year": null,
 "question": "How is a pawl for a ratchet wheel shaped?",
 "tags": [
  "pawl",
  "ratchet",
  "click",
  "one-way",
  "mechanism",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "pawl design",
  "ratchet pawl stl",
  "pawl dimensions",
  "ratchet click pawl"
 ],
 "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/ratchet-pawl/",
 "sheet_txt": "https://xemstudio.com/objects/ratchet-pawl/sheet.txt",
 "sheet": {
  "basis": "Pawl 24 mm from pivot to tip, 8 wide, 6 thick, Ø10 boss with a Ø3 pivot hole",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A flat pawl 6 thick: a Ø10 boss with a Ø3 pivot hole, an 8 mm wide arm and a pointed tip 24 mm from the pivot. Overall 29 × 10 × 6.",
   "It turns on a Ø3 pin; the tip locks against a tooth face and the sloped tooth backs lift it on the free stroke.",
   "Its contact point trails the pivot in the locking direction so load drives it into the tooth; a spring holds it down (not drawn)."
  ],
  "table": {
   "columns": [
    "feature",
    "value_mm"
   ],
   "rows": [
    [
     "pivot to tip",
     24
    ],
    [
     "arm width",
     8
    ],
    [
     "thickness",
     6
    ],
    [
     "pivot boss",
     "Ø10"
    ],
    [
     "pivot hole",
     "Ø3"
    ],
    [
     "overall",
     "29 × 10 × 6"
    ]
   ]
  }
 },
 "sheet_text": "Pawl 24 mm with a Ø3 pivot for the Ø40 ratchet wheels — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/ratchet-pawl/  (CC BY 4.0)\nBasis: Pawl 24 mm from pivot to tip, 8 wide, 6 thick, Ø10 boss with a Ø3 pivot hole\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A flat pawl 6 thick: a Ø10 boss with a Ø3 pivot hole, an 8 mm wide arm and a pointed tip 24 mm from the pivot. Overall 29 × 10 × 6.\n- It turns on a Ø3 pin; the tip locks against a tooth face and the sloped tooth backs lift it on the free stroke.\n- Its contact point trails the pivot in the locking direction so load drives it into the tooth; a spring holds it down (not drawn).\n\nfeature  value_mm\npivot to tip  24\narm width  8\nthickness  6\npivot boss  Ø10\npivot hole  Ø3\noverall  29 × 10 × 6\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Ratchet (device) — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Ratchet_(device)\n- Wikipedia: Pawl — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Pawl\n- Long Earth Society: Engine builds that use these parts (videos and write-ups) — 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/ratchet-pawl/index.json\nAPI: https://xemstudio.com/api/geometry?object=ratchet-pawl\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Ratchet (device)",
   "url": "https://en.wikipedia.org/wiki/Ratchet_(device)",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Wikipedia",
   "title": "Pawl",
   "url": "https://en.wikipedia.org/wiki/Pawl",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine builds that use these parts (videos and write-ups)",
   "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": [
  "ratchet-wheels",
  "pins-3mm",
  "torsion-spring",
  "dowel-pins-metric"
 ],
 "fits": [
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "ratchet-wheels",
     "why": "tip on the Ø40 wheel's teeth"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "pins-3mm",
     "why": "Ø3 pivot pin"
    },
    {
     "slug": "torsion-spring",
     "why": "pawl return"
    }
   ]
  }
 ],
 "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": "pawl pivot hole",
   "exact": "Ø3",
   "mates": "Ø3 pin (pawl turns on it)",
   "fit": "run",
   "files": "pawl-"
  }
 ],
 "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": "Which way does the pawl point?",
   "a": "Its contact point trails the pivot in the locking direction, so load drives it into the tooth."
  },
  {
   "q": "What does the pawl pivot on?",
   "a": "A Ø3 pin through its Ø3 hole."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "pawl-24",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/ratchet-and-pawl/pawl-24.step",
   "stl": "https://xemstudio.com/files/hardware/ratchet-and-pawl/pawl-24.stl",
   "note": "pawl 24 mm, Ø3 pivot hole, for the Ø40 wheels; spring not modeled"
  }
 ],
 "markdown": "https://xemstudio.com/objects/ratchet-pawl/index.md"
}