{
 "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": "mutilated-gear-double-rack-mechanism",
 "name": "Mutilated pinion and double rack (continuous rotation to reciprocation)",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Intermittent motion",
 "year": null,
 "question": "How does a half-toothed gear make a rack go back and forth?",
 "tags": [
  "mechanism",
  "intermittent motion",
  "kinematics",
  "507 mechanical movements"
 ],
 "aliases": [
  "mutilated gear rack",
  "reciprocating rack and pinion",
  "intermittent rack",
  "engranaje mutilado con doble cremallera",
  "Teilzahnrad mit Doppelzahnstange"
 ],
 "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/mutilated-gear-double-rack-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/mutilated-gear-double-rack-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown No. 114 (1868)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A pinion with teeth on half its rim turns continuously between two facing racks on one frame: for half a turn it drives the upper rack (frame moves one way 31.42 mm), for the other half the lower rack (frame comes back).",
   "The toothless half is cut to the root circle so it clears the other rack; the racks are spaced one pitch diameter apart (20 mm) with their teeth in phase, which keeps the hand-over clean (half a turn = 10 pitches each way).",
   "Brown's No. 114.",
   "Parts (each has its own page): mutilated-pinion-m1-20t-half, double-rack-frame-120.",
   "Brown's movement No. 114 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "pinion",
     "module 1, 10 of 20 teeth"
    ],
    [
     "rack spacing (pitch lines)",
     "20 mm"
    ],
    [
     "stroke",
     "31.42 mm each way"
    ]
   ]
  }
 },
 "sheet_text": "Mutilated pinion and double rack (continuous rotation to reciprocation) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/mutilated-gear-double-rack-mechanism/  (CC BY 4.0)\nBasis: Xem Studio design following Brown No. 114 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A pinion with teeth on half its rim turns continuously between two facing racks on one frame: for half a turn it drives the upper rack (frame moves one way 31.42 mm), for the other half the lower rack (frame comes back).\n- The toothless half is cut to the root circle so it clears the other rack; the racks are spaced one pitch diameter apart (20 mm) with their teeth in phase, which keeps the hand-over clean (half a turn = 10 pitches each way).\n- Brown's No. 114.\n- Parts (each has its own page): mutilated-pinion-m1-20t-half, double-rack-frame-120.\n- Brown's movement No. 114 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter  value\npinion  module 1, 10 of 20 teeth\nrack spacing (pitch lines)  20 mm\nstroke  31.42 mm each way\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. 114: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_114.html\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/mutilated-gear-double-rack-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=mutilated-gear-double-rack-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. 114: figure, his text and an animation",
   "url": "https://507movements.com/mm_114.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": [
  "mutilated-pinion-m1-20t-half",
  "double-rack-frame-120"
 ],
 "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 does a half-toothed gear make a rack go back and forth?",
   "a": "A pinion with teeth on half its rim turns continuously between two facing racks on one frame: for half a turn it drives the upper rack (frame moves one way 31.42 mm), for the other half the lower rack (frame comes back)."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "mutilated-gear-double-rack-mechanism-assembly",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/mutilated-gear-double-rack-mechanism/mutilated-gear-double-rack-mechanism-assembly.step",
   "stl": "https://xemstudio.com/files/hardware/mutilated-gear-double-rack-mechanism/mutilated-gear-double-rack-mechanism-assembly.stl",
   "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/mutilated-gear-double-rack-mechanism/index.md"
}