{
 "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": "planetary-crank-variable-traverse-mechanism",
 "name": "Planet-gear crank on a carrier round a fixed sun (variable traverse)",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Gears",
 "year": null,
 "question": "How does a planet-gear crank vary a slider's stroke?",
 "tags": [
  "mechanism",
  "gears",
  "kinematics",
  "507 mechanical movements"
 ],
 "aliases": [
  "planetary crank",
  "variable stroke crank",
  "epicyclic crank traverse",
  "manivela planetaria de carrera variable",
  "Planetenkurbel mit veränderlichem Hub"
 ],
 "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/planetary-crank-variable-traverse-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/planetary-crank-variable-traverse-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown No. 142 (1868)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A 30-tooth sun gear is fixed; a carrier disc turns about it carrying a 30-tooth planet that rolls round the sun, making two turns per carrier turn. A crank pin on the planet (10 mm out) therefore traces a curve whose distance from the centre swings between 20 and 40 mm, and the rod from the pin to the slider gives a traverse that lengthens and shortens from stroke to stroke: Brown's variable-traverse motion for winding and tool feeds.",
   "Drawn at carrier angle 50° (planet turned 274°): pin at (20.5, 13.06), slider at x = 119.65 on the catalog slot guide, rod 100 mm.",
   "Brown's No. 142; module 1 throughout, centre distance 30 mm, the catalog 30 T crank gear and the catalog 30 T gear (sun) on a Ø10 shaft.",
   "Parts (each has its own page): spur-gears-module-1, crank-gear-m1-30t-pin-r10, planet-crank-carrier-disc-52-r30-boss10, four-bar-links, slide-block-12x6, slot-guide-plate-90, linear-shafts-h6, dowel-pins-metric.",
   "Brown's movement No. 142 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "sun / planet",
     "30 T / 30 T, module 1"
    ],
    [
     "carrier radius",
     "30 mm"
    ],
    [
     "crank pin",
     "10 mm on the planet"
    ],
    [
     "effective crank",
     "20 – 40 mm"
    ],
    [
     "rod",
     "100 mm"
    ]
   ]
  }
 },
 "sheet_text": "Planet-gear crank on a carrier round a fixed sun (variable traverse) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/planetary-crank-variable-traverse-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Xem Studio design following Brown No. 142 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A 30-tooth sun gear is fixed; a carrier disc turns about it carrying a 30-tooth planet that rolls round the sun, making two turns per carrier turn. A crank pin on the planet (10 mm out) therefore traces a curve whose distance from the centre swings between 20 and 40 mm, and the rod from the pin to the slider gives a traverse that lengthens and shortens from stroke to stroke: Brown's variable-traverse motion for winding and tool feeds.\n- Drawn at carrier angle 50° (planet turned 274°): pin at (20.5, 13.06), slider at x = 119.65 on the catalog slot guide, rod 100 mm.\n- Brown's No. 142; module 1 throughout, centre distance 30 mm, the catalog 30 T crank gear and the catalog 30 T gear (sun) on a Ø10 shaft.\n- Parts (each has its own page): spur-gears-module-1, crank-gear-m1-30t-pin-r10, planet-crank-carrier-disc-52-r30-boss10, four-bar-links, slide-block-12x6, slot-guide-plate-90, linear-shafts-h6, dowel-pins-metric.\n- Brown's movement No. 142 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter  value\nsun / planet  30 T / 30 T, module 1\ncarrier radius  30 mm\ncrank pin  10 mm on the planet\neffective crank  20 – 40 mm\nrod  100 mm\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. 142: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_142.html\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/planetary-crank-variable-traverse-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=planetary-crank-variable-traverse-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. 142: figure, his text and an animation",
   "url": "https://507movements.com/mm_142.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": [
  "spur-gears-module-1",
  "crank-gear-m1-30t-pin-r10",
  "planet-crank-carrier-disc-52-r30-boss10",
  "four-bar-links",
  "slide-block-12x6",
  "slot-guide-plate-90",
  "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 does a planet-gear crank vary a slider's stroke?",
   "a": "A 30-tooth sun gear is fixed; a carrier disc turns about it carrying a 30-tooth planet that rolls round the sun, making two turns per carrier turn. A crank pin on the planet (10 mm out) therefore traces a curve whose distance from the centre swings between 20 and 40 mm, and the rod from the pin to the slider gives a traverse that lengthens and shortens from stroke to stroke: Brown's variable-traverse motion for winding and tool feeds."
  }
 ],
 "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": "planetary-crank-variable-traverse-mechanism-assembly",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/planetary-crank-variable-traverse-mechanism/planetary-crank-variable-traverse-mechanism-assembly.step",
   "stl": "https://xemstudio.com/files/hardware/planetary-crank-variable-traverse-mechanism/planetary-crank-variable-traverse-mechanism-assembly.stl",
   "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/planetary-crank-variable-traverse-mechanism/index.md"
}