{
 "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": "watts-linkage-mechanism",
 "name": "Watt's linkage (straight-line motion), 60 / 30 / 60",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Linkages",
 "year": null,
 "question": "How straight is Watt's linkage?",
 "tags": [
  "mechanism",
  "linkages",
  "kinematics",
  "507 mechanical movements"
 ],
 "aliases": [
  "watts linkage",
  "watt parallel motion",
  "straight line linkage",
  "watt linkage suspension",
  "mecanismo de Watt",
  "Wattsches Gestänge"
 ],
 "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/watts-linkage-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/watts-linkage-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown No. 337 (1868)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Two equal radius arms swinging in opposite directions, joined by a short coupler: the coupler's midpoint moves on a figure-eight whose middle part is very nearly straight — Watt's 1784 parallel motion for a beam-driven rod.",
   "Here: arms 60 mm, coupler 30 mm, fixed pivots ±60 mm apart horizontally and 30 mm vertically. At 12° the midpoint is at x = 0.01 mm (straight line x = 0); over ±10° of arm swing it stays within about 0.1 mm of the line.",
   "Brown's No. 337 (radius rod on the lower end of a short link hung from the beam, rod at its centre); the same linkage locates car axles sideways.",
   "Parts (each has its own page): four-bar-links, watt-linkage-coupler-30, dowel-pins-metric.",
   "Brown's movement No. 337 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "radius arms",
     "2 × 60 mm"
    ],
    [
     "coupler",
     "30 mm"
    ],
    [
     "fixed pivots",
     "(−60, 15) and (60, −15) mm"
    ],
    [
     "tracer",
     "coupler midpoint"
    ]
   ]
  }
 },
 "sheet_text": "Watt's linkage (straight-line motion), 60 / 30 / 60 — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/watts-linkage-mechanism/  (CC BY 4.0)\nBasis: Xem Studio design following Brown No. 337 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Two equal radius arms swinging in opposite directions, joined by a short coupler: the coupler's midpoint moves on a figure-eight whose middle part is very nearly straight — Watt's 1784 parallel motion for a beam-driven rod.\n- Here: arms 60 mm, coupler 30 mm, fixed pivots ±60 mm apart horizontally and 30 mm vertically. At 12° the midpoint is at x = 0.01 mm (straight line x = 0); over ±10° of arm swing it stays within about 0.1 mm of the line.\n- Brown's No. 337 (radius rod on the lower end of a short link hung from the beam, rod at its centre); the same linkage locates car axles sideways.\n- Parts (each has its own page): four-bar-links, watt-linkage-coupler-30, dowel-pins-metric.\n- Brown's movement No. 337 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter  value\nradius arms  2 × 60 mm\ncoupler  30 mm\nfixed pivots  (−60, 15) and (60, −15) mm\ntracer  coupler midpoint\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. 337: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_337.html\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/watts-linkage-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=watts-linkage-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. 337: figure, his text and an animation",
   "url": "https://507movements.com/mm_337.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": [
  "four-bar-links",
  "watt-linkage-coupler-30",
  "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 straight is Watt's linkage?",
   "a": "Two equal radius arms swinging in opposite directions, joined by a short coupler: the coupler's midpoint moves on a figure-eight whose middle part is very nearly straight — Watt's 1784 parallel motion for a beam-driven rod."
  },
  {
   "q": "Is Watt's linkage exactly straight?",
   "a": "No: the midpoint traces a lemniscate-like curve, nearly straight near the middle; Peaucellier's linkage (1864) is the first exact one."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "watts-linkage-mechanism-assembly",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/watts-linkage-mechanism/watts-linkage-mechanism-assembly.step",
   "stl": "https://xemstudio.com/files/hardware/watts-linkage-mechanism/watts-linkage-mechanism-assembly.stl",
   "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/watts-linkage-mechanism/index.md"
}