{
 "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": "bevel-reversing-gear-fast-loose-pulleys-mechanism",
 "name": "Fast and loose pulleys with bevel gears: start, stop or reverse an upright shaft",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Gears",
 "year": null,
 "question": "How do fast and loose pulleys reverse a shaft through bevel gears?",
 "tags": [
  "mechanism",
  "gears",
  "kinematics",
  "507 mechanical movements"
 ],
 "aliases": [
  "reversing gear",
  "bevel reversing gear",
  "fast and loose pulleys",
  "mitre gear reverse",
  "inversor con engranajes cónicos y poleas",
  "Wendegetriebe mit Kegelrädern und Riemen"
 ],
 "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/bevel-reversing-gear-fast-loose-pulleys-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/bevel-reversing-gear-fast-loose-pulleys-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown No. 7 (1868)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Resize: multiply every length by one factor k and the motion stays identical: angles, ratios, timing and the formulas below do not change, because a mechanism's motion depends only on the ratios of its lengths. Here, scales with k: pulleys, driving pulley; stays the same: gears; step to the nearest standard size (and redraw the hole or pocket it fits): upright shaft.",
   "Resize: Gears scale by the module m (pitch Ø = m·z, centre distance = m·(z₁ + z₂)/2): keep the tooth counts so the ratio stays, and choose a standard module (0.5, 0.8, 1, 1.25, 1.5, 2, 2.5, 3).",
   "Resize: fit clearances stay in mm (a slide fit is the same gap at any size); keep every printed wall and pin at least two nozzle widths; mass grows with k³ but part strength only with k², so at k = 2 parts are about 8× heavier and 4× stronger: check pins and thin links when scaling up.",
   "Two mitre gears face each other on a cross shaft and both mesh with a third on the upright shaft. One (A) is keyed to the cross shaft, which carries the fast pulley; the other (B) runs loose with its own pulley; between them is a loose idler pulley.",
   "Belt on the fast pulley: the shaft turns gear A and the upright shaft turns one way. Belt on B's pulley: gear B, on the other side of the upright gear, turns it the other way. Belt on the idler: it stops. The belt is shifted sideways along the wide driving pulley. Brown draws the two bevels on a shaft and a hollow shaft one inside the other; here B simply runs loose on the one shaft.",
   "Three module 2, 24-tooth spherical-involute mitre gears (cone distance 33.94 mm), Ø40 × 16 pulleys on a Ø5 shaft; the three gears were checked in mesh at six angles. Brown's No. 7.",
   "Parts (each has its own page): mitre-gear-m2-24t-bore5, plain-flat-pulley-40x16-bore5, plain-flat-pulley-40x52, flat-belt-16x1-5-pulleys-40-40-c130, linear-shafts-h6.",
   "Brown's movement No. 7 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "gears",
     "3 × mitre, module 2, 24 T"
    ],
    [
     "pulleys",
     "3 × Ø40 × 16 (fast, idle, loose)"
    ],
    [
     "driving pulley",
     "Ø40 × 52, 130 mm above"
    ],
    [
     "upright shaft",
     "same speed, either direction"
    ]
   ]
  }
 },
 "sheet_text": "Fast and loose pulleys with bevel gears: start, stop or reverse an upright shaft — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/bevel-reversing-gear-fast-loose-pulleys-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Xem Studio design following Brown No. 7 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Resize: multiply every length by one factor k and the motion stays identical: angles, ratios, timing and the formulas below do not change, because a mechanism's motion depends only on the ratios of its lengths. Here, scales with k: pulleys, driving pulley; stays the same: gears; step to the nearest standard size (and redraw the hole or pocket it fits): upright shaft.\n- Resize: Gears scale by the module m (pitch Ø = m·z, centre distance = m·(z₁ + z₂)/2): keep the tooth counts so the ratio stays, and choose a standard module (0.5, 0.8, 1, 1.25, 1.5, 2, 2.5, 3).\n- Resize: fit clearances stay in mm (a slide fit is the same gap at any size); keep every printed wall and pin at least two nozzle widths; mass grows with k³ but part strength only with k², so at k = 2 parts are about 8× heavier and 4× stronger: check pins and thin links when scaling up.\n- Two mitre gears face each other on a cross shaft and both mesh with a third on the upright shaft. One (A) is keyed to the cross shaft, which carries the fast pulley; the other (B) runs loose with its own pulley; between them is a loose idler pulley.\n- Belt on the fast pulley: the shaft turns gear A and the upright shaft turns one way. Belt on B's pulley: gear B, on the other side of the upright gear, turns it the other way. Belt on the idler: it stops. The belt is shifted sideways along the wide driving pulley. Brown draws the two bevels on a shaft and a hollow shaft one inside the other; here B simply runs loose on the one shaft.\n- Three module 2, 24-tooth spherical-involute mitre gears (cone distance 33.94 mm), Ø40 × 16 pulleys on a Ø5 shaft; the three gears were checked in mesh at six angles. Brown's No. 7.\n- Parts (each has its own page): mitre-gear-m2-24t-bore5, plain-flat-pulley-40x16-bore5, plain-flat-pulley-40x52, flat-belt-16x1-5-pulleys-40-40-c130, linear-shafts-h6.\n- Brown's movement No. 7 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter  value\ngears  3 × mitre, module 2, 24 T\npulleys  3 × Ø40 × 16 (fast, idle, loose)\ndriving pulley  Ø40 × 52, 130 mm above\nupright shaft  same speed, either direction\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. 7: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_007.html\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/bevel-reversing-gear-fast-loose-pulleys-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=bevel-reversing-gear-fast-loose-pulleys-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. 7: figure, his text and an animation",
   "url": "https://507movements.com/mm_007.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": [
  "mitre-gear-m2-24t-bore5",
  "plain-flat-pulley-40x16-bore5",
  "plain-flat-pulley-40x52",
  "flat-belt-16x1-5-pulleys-40-40-c130",
  "linear-shafts-h6"
 ],
 "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 do fast and loose pulleys reverse a shaft through bevel gears?",
   "a": "Two mitre gears face each other on a cross shaft and both mesh with a third on the upright shaft. One (A) is keyed to the cross shaft, which carries the fast pulley; the other (B) runs loose with its own pulley; between them is a loose idler pulley."
  }
 ],
 "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": "bevel-reversing-gear-fast-loose-pulleys-mechanism-assembly",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/bevel-reversing-gear-fast-loose-pulleys-mechanism/bevel-reversing-gear-fast-loose-pulleys-mechanism-assembly.step",
   "stl": "https://xemstudio.com/files/hardware/bevel-reversing-gear-fast-loose-pulleys-mechanism/bevel-reversing-gear-fast-loose-pulleys-mechanism-assembly.stl",
   "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/bevel-reversing-gear-fast-loose-pulleys-mechanism/index.md"
}