{
 "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": "constant-breadth-cam-yoke-mechanism",
 "name": "Constant-breadth cam turning in a yoke (three strokes per turn)",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Cams",
 "year": null,
 "question": "How does a constant-breadth cam reciprocate a bar?",
 "tags": [
  "mechanism",
  "cams",
  "kinematics",
  "507 mechanical movements"
 ],
 "aliases": [
  "constant breadth cam",
  "reuleaux cam yoke",
  "three throw cam",
  "leva de anchura constante en yugo",
  "Gleichdick im Rahmen"
 ],
 "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/constant-breadth-cam-yoke-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/constant-breadth-cam-yoke-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown No. 276 (1868)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A cam of constant breadth (a Reuleaux triangle with rounded corners) turns about its centre between two parallel faces of a yoke exactly its breadth apart, so it touches both at every angle and drives the yoke both ways. Its distance to each face changes from the corner radius to the flank radius: the yoke moves 4.64 mm to and fro three times per turn of the cam.",
   "Breadth 40 (side 30, corners R5); drawn at 20°, the yoke 2.06 mm from centre.",
   "Brown's No. 276 (cam giving a reciprocating motion to a bar); the corner-pivoted triangle of No. 91 gives one long stroke with dwells instead.",
   "Parts (each has its own page): constant-breadth-cam-s30-r5-bore5, constant-breadth-cam-yoke-40, dowel-pins-metric.",
   "Brown's movement No. 276 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "breadth",
     "40 mm"
    ],
    [
     "pivot",
     "centre"
    ],
    [
     "stroke",
     "4.64 mm"
    ],
    [
     "strokes per turn",
     "3"
    ]
   ]
  }
 },
 "sheet_text": "Constant-breadth cam turning in a yoke (three strokes per turn) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/constant-breadth-cam-yoke-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Xem Studio design following Brown No. 276 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A cam of constant breadth (a Reuleaux triangle with rounded corners) turns about its centre between two parallel faces of a yoke exactly its breadth apart, so it touches both at every angle and drives the yoke both ways. Its distance to each face changes from the corner radius to the flank radius: the yoke moves 4.64 mm to and fro three times per turn of the cam.\n- Breadth 40 (side 30, corners R5); drawn at 20°, the yoke 2.06 mm from centre.\n- Brown's No. 276 (cam giving a reciprocating motion to a bar); the corner-pivoted triangle of No. 91 gives one long stroke with dwells instead.\n- Parts (each has its own page): constant-breadth-cam-s30-r5-bore5, constant-breadth-cam-yoke-40, dowel-pins-metric.\n- Brown's movement No. 276 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter  value\nbreadth  40 mm\npivot  centre\nstroke  4.64 mm\nstrokes per turn  3\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. 276: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_276.html\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/constant-breadth-cam-yoke-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=constant-breadth-cam-yoke-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. 276: figure, his text and an animation",
   "url": "https://507movements.com/mm_276.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": [
  "constant-breadth-cam-s30-r5-bore5",
  "constant-breadth-cam-yoke-40",
  "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 does a constant-breadth cam reciprocate a bar?",
   "a": "A cam of constant breadth (a Reuleaux triangle with rounded corners) turns about its centre between two parallel faces of a yoke exactly its breadth apart, so it touches both at every angle and drives the yoke both ways. Its distance to each face changes from the corner radius to the flank radius: the yoke moves 4.64 mm to and fro three times per turn of the cam."
  }
 ],
 "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": "constant-breadth-cam-yoke-mechanism-assembly",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/constant-breadth-cam-yoke-mechanism/constant-breadth-cam-yoke-mechanism-assembly.step",
   "stl": "https://xemstudio.com/files/hardware/constant-breadth-cam-yoke-mechanism/constant-breadth-cam-yoke-mechanism-assembly.stl",
   "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/constant-breadth-cam-yoke-mechanism/index.md"
}