{
 "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": "uniform-motion-crank-yoke-mechanism",
 "name": "Crank with closed channel yoke (uniform-speed reciprocation)",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Cams",
 "year": null,
 "question": "How can a crank give uniform straight-line speed?",
 "tags": [
  "mechanism",
  "cams",
  "kinematics",
  "507 mechanical movements"
 ],
 "aliases": [
  "uniform velocity crank",
  "constant speed yoke",
  "crank channel yoke",
  "manivela con yugo de velocidad uniforme",
  "Kurbel mit Gleichlaufkulisse"
 ],
 "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/uniform-motion-crank-yoke-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/uniform-motion-crank-yoke-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown No. 354 (1868)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A plain crank pin runs in a closed channel cut in the crosshead instead of a straight slot. The channel's shape is the pin's path relative to a crosshead moving at constant speed, so the crosshead travels 24 mm out at uniform speed during half a turn and back during the other half — a crank made to behave like a heart cam.",
   "Drawn at θ = 50°: crosshead at x = -5.33 mm, the Ø3 pin touching both walls of the 3 mm channel. Direction reverses sharply at the channel's two points (θ = 0° and 180°), the price of uniform speed.",
   "Brown's No. 354 (crank and slotted cross-head modified for uniform velocity, from No. 93).",
   "Parts (each has its own page): crank-disc-36-pin-r12, uniform-motion-yoke-plate-60x40-r12, linear-shafts-h6, dowel-pins-metric.",
   "Brown's movement No. 354 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "crank radius",
     "12 mm"
    ],
    [
     "stroke",
     "24 mm, uniform speed"
    ],
    [
     "channel",
     "3 mm, closed loop"
    ],
    [
     "speed",
     "48 mm per crank turn"
    ]
   ]
  }
 },
 "sheet_text": "Crank with closed channel yoke (uniform-speed reciprocation) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/uniform-motion-crank-yoke-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Xem Studio design following Brown No. 354 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A plain crank pin runs in a closed channel cut in the crosshead instead of a straight slot. The channel's shape is the pin's path relative to a crosshead moving at constant speed, so the crosshead travels 24 mm out at uniform speed during half a turn and back during the other half — a crank made to behave like a heart cam.\n- Drawn at θ = 50°: crosshead at x = -5.33 mm, the Ø3 pin touching both walls of the 3 mm channel. Direction reverses sharply at the channel's two points (θ = 0° and 180°), the price of uniform speed.\n- Brown's No. 354 (crank and slotted cross-head modified for uniform velocity, from No. 93).\n- Parts (each has its own page): crank-disc-36-pin-r12, uniform-motion-yoke-plate-60x40-r12, linear-shafts-h6, dowel-pins-metric.\n- Brown's movement No. 354 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter  value\ncrank radius  12 mm\nstroke  24 mm, uniform speed\nchannel  3 mm, closed loop\nspeed  48 mm per crank turn\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. 354: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_354.html\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/uniform-motion-crank-yoke-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=uniform-motion-crank-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. 354: figure, his text and an animation",
   "url": "https://507movements.com/mm_354.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": [
  "crank-disc-36-pin-r12",
  "uniform-motion-yoke-plate-60x40-r12",
  "linear-shafts-h6",
  "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 crank give uniform straight-line speed?",
   "a": "A plain crank pin runs in a closed channel cut in the crosshead instead of a straight slot. The channel's shape is the pin's path relative to a crosshead moving at constant speed, so the crosshead travels 24 mm out at uniform speed during half a turn and back during the other half — a crank made to behave like a heart 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": "uniform-motion-crank-yoke-mechanism-assembly",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/uniform-motion-crank-yoke-mechanism/uniform-motion-crank-yoke-mechanism-assembly.step",
   "stl": "https://xemstudio.com/files/hardware/uniform-motion-crank-yoke-mechanism/uniform-motion-crank-yoke-mechanism-assembly.stl",
   "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/uniform-motion-crank-yoke-mechanism/index.md"
}