{
 "version": "2026-10-20",
 "license": "Dimension sheets: CC BY 4.0. Standard and published-size files: CC BY 4.0. Xem Studio's own designs (files_license = Xem Studio Design License): free to use and sell things from, not to redistribute as files — https://xemstudio.com/license/. Other publishers' files: their own license, linked beside them.",
 "slug": "double-pawl-lever-ratchet-mechanism",
 "name": "Lever with two pawls driving a ratchet on both strokes",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Intermittent motion",
 "year": null,
 "question": "How can a lever drive a ratchet on both its strokes?",
 "tags": [
  "mechanism",
  "intermittent motion",
  "kinematics",
  "507 mechanical movements"
 ],
 "aliases": [
  "double pawl ratchet",
  "two pawl lever",
  "continuous ratchet drive",
  "palanca de dos trinquetes",
  "Doppelklinkenschaltwerk"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/double-pawl-lever-ratchet-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/double-pawl-lever-ratchet-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown No. 206 (1868)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A lever rocks on a fulcrum beside the ratchet wheel and carries two pawls, pinned one above and one below the fulcrum. Swinging the handle one way, the upper pawl pivot moves toward the wheel and its pawl pushes a tooth; swinging it back, the lower pivot moves toward the wheel and the lower pawl pushes another tooth, while the first slides back over the teeth. The wheel is driven the same way on both strokes, so the motion is nearly continuous.",
   "Catalog Ø40, 24-tooth ratchet; both pawls drawn with their end faces lying on the steep faces of two teeth (face contact, no overlap) at the same instant.",
   "Brown's No. 206 (lever with rising and falling pawls giving a nearly continuous rotary motion to a ratchet wheel).",
   "Parts (each has its own page): ratchet-and-pawl, lever-pawl-24t-d40-upper, lever-pawl-24t-d40-lower, double-pawl-lever-fulcrum-handle-80, dowel-pins-metric.",
   "Brown's movement No. 206 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "ratchet",
     "24 T, Ø40"
    ],
    [
     "pawls",
     "2, face contact"
    ],
    [
     "drive",
     "both strokes, same direction"
    ]
   ]
  }
 },
 "sheet_text": "Lever with two pawls driving a ratchet on both strokes — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/double-pawl-lever-ratchet-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Xem Studio design following Brown No. 206 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A lever rocks on a fulcrum beside the ratchet wheel and carries two pawls, pinned one above and one below the fulcrum. Swinging the handle one way, the upper pawl pivot moves toward the wheel and its pawl pushes a tooth; swinging it back, the lower pivot moves toward the wheel and the lower pawl pushes another tooth, while the first slides back over the teeth. The wheel is driven the same way on both strokes, so the motion is nearly continuous.\n- Catalog Ø40, 24-tooth ratchet; both pawls drawn with their end faces lying on the steep faces of two teeth (face contact, no overlap) at the same instant.\n- Brown's No. 206 (lever with rising and falling pawls giving a nearly continuous rotary motion to a ratchet wheel).\n- Parts (each has its own page): ratchet-and-pawl, lever-pawl-24t-d40-upper, lever-pawl-24t-d40-lower, double-pawl-lever-fulcrum-handle-80, dowel-pins-metric.\n- Brown's movement No. 206 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter  value\nratchet  24 T, Ø40\npawls  2, face contact\ndrive  both strokes, same direction\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Henry T. Brown (1868, public domain): Five Hundred and Seven Mechanical Movements — scan on archive.org — web — Publisher's page; dimensions are facts — https://archive.org/details/fivehundredseven00browiala\n- 507movements.com: Brown's movement No. 206: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_206.html\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/double-pawl-lever-ratchet-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=double-pawl-lever-ratchet-mechanism\n",
 "sources": [
  {
   "publisher": "Henry T. Brown (1868, public domain)",
   "title": "Five Hundred and Seven Mechanical Movements — scan on archive.org",
   "url": "https://archive.org/details/fivehundredseven00browiala",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "507movements.com",
   "title": "Brown's movement No. 206: figure, his text and an animation",
   "url": "https://507movements.com/mm_206.html",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "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",
  "lever-pawl-24t-d40-upper",
  "lever-pawl-24t-d40-lower",
  "double-pawl-lever-fulcrum-handle-80",
  "dowel-pins-metric"
 ],
 "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": [],
 "faq": [
  {
   "q": "How can a lever drive a ratchet on both its strokes?",
   "a": "A lever rocks on a fulcrum beside the ratchet wheel and carries two pawls, pinned one above and one below the fulcrum. Swinging the handle one way, the upper pawl pivot moves toward the wheel and its pawl pushes a tooth; swinging it back, the lower pivot moves toward the wheel and the lower pawl pushes another tooth, while the first slides back over the teeth. The wheel is driven the same way on both strokes, so the motion is nearly continuous."
  }
 ],
 "files_license": {
  "name": "Xem Studio Design License",
  "holder": "Xem Studio",
  "url": "https://xemstudio.com/license/",
  "note": "Xem Studio's own design: free to use, print, modify and sell things made from it; not to be republished or redistributed as files."
 },
 "offers": [
  {
   "file": "double-pawl-lever-ratchet-mechanism-assembly",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/double-pawl-lever-ratchet-mechanism/double-pawl-lever-ratchet-mechanism-assembly.step",
   "stl": "https://xemstudio.com/files/hardware/double-pawl-lever-ratchet-mechanism/double-pawl-lever-ratchet-mechanism-assembly.stl",
   "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/double-pawl-lever-ratchet-mechanism/index.md"
}