{
 "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": "ackermann",
 "name": "Ackermann steering geometry",
 "kind": "standard",
 "category": "Car design",
 "group": "Suspension geometry",
 "year": null,
 "question": "What is Ackermann steering and how is it calculated?",
 "tags": [
  "vehicle design",
  "suspension geometry",
  "rc design",
  "aerodynamics"
 ],
 "aliases": [
  "ackermann",
  "ackerman steering",
  "ackermann geometry",
  "ackermann angle",
  "rc ackermann",
  "steering geometry inner wheel",
  "ackermann formula",
  "100% ackermann",
  "ackermann plate",
  "steering trapezoid"
 ],
 "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/ackermann/",
 "sheet_txt": "https://xemstudio.com/objects/ackermann/sheet.txt",
 "sheet": {
  "basis": "Design rules and figures from the cited sources; example geometry by Xem Studio",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Ackermann geometry turns the inside wheel more than the outside so both roll around one common centre without scrubbing (Wikipedia). The ideal condition is cot(outer) - cot(inner) = track / wheelbase (raw.org).",
   "A simple layout points the steering arms toward the centre of the rear axle so the tie rod and axle form a trapezium (Wikipedia).",
   "On RC cars more Ackermann gives sharper turn-in but can feel twitchy at speed and wears the inside front tyre (CompetitionX); Tekno adjusts it by moving the steering link fore or aft.",
   "The file is a reference example built by Xem Studio from the numbers above (Reference 1/10 touring car: wheelbase 260 mm (AARCMCC ISTC 250-270), track 190 mm (EFRA width without body), 50 mm = EFRA rim limit.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle."
  ],
  "table": {
   "columns": [
    "parameter",
    "value or range",
    "source"
   ],
   "rows": [
    [
     "Ackermann condition",
     "cot(phi_o) - cot(phi_i) = w / l",
     "raw.org"
    ],
    [
     "Inner wheel angle",
     "phi_i = atan(2l sin phi / (2l cos phi - w sin phi))",
     "raw.org"
    ],
    [
     "Steering-arm rule",
     "arm pivots on line from kingpin to rear-axle centre",
     "Wikipedia"
    ],
    [
     "Invented",
     "Lankensperger 1816; Ackermann patent 1818",
     "Wikipedia"
    ]
   ]
  }
 },
 "sheet_text": "Ackermann steering geometry — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/ackermann/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Design rules and figures from the cited sources; example geometry by Xem Studio\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Ackermann geometry turns the inside wheel more than the outside so both roll around one common centre without scrubbing (Wikipedia). The ideal condition is cot(outer) - cot(inner) = track / wheelbase (raw.org).\n- A simple layout points the steering arms toward the centre of the rear axle so the tie rod and axle form a trapezium (Wikipedia).\n- On RC cars more Ackermann gives sharper turn-in but can feel twitchy at speed and wears the inside front tyre (CompetitionX); Tekno adjusts it by moving the steering link fore or aft.\n- The file is a reference example built by Xem Studio from the numbers above (Reference 1/10 touring car: wheelbase 260 mm (AARCMCC ISTC 250-270), track 190 mm (EFRA width without body), 50 mm = EFRA rim limit.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.\n\nparameter  value or range  source\nAckermann condition  cot(phi_o) - cot(phi_i) = w / l  raw.org\nInner wheel angle  phi_i = atan(2l sin phi / (2l cos phi - w sin phi))  raw.org\nSteering-arm rule  arm pivots on line from kingpin to rear-axle centre  Wikipedia\nInvented  Lankensperger 1816; Ackermann patent 1818  Wikipedia\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- raw.org (kinematics notes): Ackerman steering — web — Publisher's page; dimensions are facts — https://raw.org/book/kinematics/ackerman-steering/\n- Wikipedia: Ackermann steering geometry — web — Publisher's page; dimensions are facts — https://en.wikipedia.org/wiki/Ackermann_steering_geometry\n- CompetitionX: RC Ackermann Steering Explained — web — Publisher's page; dimensions are facts — https://www.competitionx.com/?p=14\n- Tekno RC: Tekno RC Setup Guide — web — Publisher's page; dimensions are facts — https://teknoforums.com/misc/Tekno-RC-Setup-Guide.pdf\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/ackermann/index.json\nAPI: https://xemstudio.com/api/geometry?object=ackermann\n",
 "sources": [
  {
   "publisher": "raw.org (kinematics notes)",
   "title": "Ackerman steering",
   "url": "https://raw.org/book/kinematics/ackerman-steering/",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Wikipedia",
   "title": "Ackermann steering geometry",
   "url": "https://en.wikipedia.org/wiki/Ackermann_steering_geometry",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "CompetitionX",
   "title": "RC Ackermann Steering Explained",
   "url": "https://www.competitionx.com/?p=14",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Tekno RC",
   "title": "Tekno RC Setup Guide",
   "url": "https://teknoforums.com/misc/Tekno-RC-Setup-Guide.pdf",
   "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": [
  "camber",
  "caster",
  "kick-up",
  "toe-front",
  "toe-rear",
  "anti-ackermann"
 ],
 "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": "Does Ackermann depend on wheelbase?",
   "a": "Yes; the ideal difference between wheel angles grows with track/wheelbase (raw.org)."
  }
 ],
 "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": "ackermann-geometry",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/ackermann/ackermann-geometry.step",
   "stl": "https://xemstudio.com/files/hardware/ackermann/ackermann-geometry.stl",
   "note": "Ackermann demo: inner wheel 30°, outer wheel per the Ackermann relation for wheelbase 260, track 190 (illustrative layout)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/ackermann/index.md"
}