{
 "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": "opposed-racks-and-pinion-mechanism",
 "name": "Pinion between two racks (opposite motion, pump drive)",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Gears",
 "year": null,
 "question": "How does one pinion move two racks in opposite directions?",
 "tags": [
  "mechanism",
  "gears",
  "kinematics",
  "507 mechanical movements"
 ],
 "aliases": [
  "double rack and pinion",
  "opposed racks",
  "rack pump drive",
  "piñón entre dos cremalleras",
  "Ritzel zwischen zwei Zahnstangen"
 ],
 "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/opposed-racks-and-pinion-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/opposed-racks-and-pinion-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown No. 127 (1868)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A pinion between two parallel racks drives them in opposite directions at the same speed: rocking the lever on the pinion's shaft raises one rack (and its pump piston) while lowering the other.",
   "Racks are two full-depth module 1, 120 mm racks with their pitch lines 20 mm apart (one pitch diameter of the 20-tooth pinion); each moves π·m·N = 62.83 mm per pinion turn.",
   "Brown's No. 127 (air pump: lever and spur gear driving two racks on the piston rods).",
   "Parts (each has its own page): gear-rack-m1-120-full-depth, spur-gears-module-1, hand-lever-60-bore6, dowel-pins-metric.",
   "Brown's movement No. 127 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "pinion",
     "20 T, module 1"
    ],
    [
     "racks",
     "2 × 120 mm, pitch lines 20 mm apart"
    ],
    [
     "travel",
     "62.83 mm per turn, opposite ways"
    ],
    [
     "lever",
     "60 mm"
    ]
   ]
  }
 },
 "sheet_text": "Pinion between two racks (opposite motion, pump drive) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/opposed-racks-and-pinion-mechanism/  (CC BY 4.0)\nBasis: Xem Studio design following Brown No. 127 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A pinion between two parallel racks drives them in opposite directions at the same speed: rocking the lever on the pinion's shaft raises one rack (and its pump piston) while lowering the other.\n- Racks are two full-depth module 1, 120 mm racks with their pitch lines 20 mm apart (one pitch diameter of the 20-tooth pinion); each moves π·m·N = 62.83 mm per pinion turn.\n- Brown's No. 127 (air pump: lever and spur gear driving two racks on the piston rods).\n- Parts (each has its own page): gear-rack-m1-120-full-depth, spur-gears-module-1, hand-lever-60-bore6, dowel-pins-metric.\n- Brown's movement No. 127 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter  value\npinion  20 T, module 1\nracks  2 × 120 mm, pitch lines 20 mm apart\ntravel  62.83 mm per turn, opposite ways\nlever  60 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. 127: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_127.html\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/opposed-racks-and-pinion-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=opposed-racks-and-pinion-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. 127: figure, his text and an animation",
   "url": "https://507movements.com/mm_127.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": [
  "gear-rack-m1-120-full-depth",
  "spur-gears-module-1",
  "hand-lever-60-bore6",
  "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 one pinion move two racks in opposite directions?",
   "a": "A pinion between two parallel racks drives them in opposite directions at the same speed: rocking the lever on the pinion's shaft raises one rack (and its pump piston) while lowering the other."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "opposed-racks-and-pinion-mechanism-assembly",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/opposed-racks-and-pinion-mechanism/opposed-racks-and-pinion-mechanism-assembly.step",
   "stl": "https://xemstudio.com/files/hardware/opposed-racks-and-pinion-mechanism/opposed-racks-and-pinion-mechanism-assembly.stl",
   "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/opposed-racks-and-pinion-mechanism/index.md"
}