Xem Studiomeasured geometry

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Stepped cone pulleys (three speeds by moving the belt)

How do stepped cone pulleys change speed? · Hardware · basis: Xem Studio design following Brown No. 8 (1868)

Also called: cone pulleys, step pulleys, speed cone pulleys, poleas escalonadas, Stufenscheibentrieb

Exact dimensions. True size, with no printing tolerance added.

sizes
4 in table

Notes

  • Two identical stepped pulleys mounted head to tail: moving the belt from one step pair to another changes the speed ratio — 50/30 = 1.67, 40/40 = 1, 30/50 = 0.6 — while the belt length stays the same because each pair's diameters add to 80 mm.
  • Drawn with the belt on the middle (Ø40 / Ø40) steps, shafts 120 mm apart; belt inside length 365.66 mm.
  • Brown's No. 8 (speed pulleys); the classic lathe and drill-press drive.
  • Parts (each has its own page): stepped-cone-pulley-50-40-30, flat-belt-1-5x16-pulleys-40-120.
  • Brown's movement No. 8 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

Stepped cone pulleys size chart

parametervalue
stepsØ50 / Ø40 / Ø30 (×2, reversed)
ratios1.67, 1, 0.6
shaft centres120 mm
belt16 × 1.5 flat

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

Henry T. Brown (1868, public domain)Five Hundred and Seven Mechanical Movements — scan on archive.orgwebPublisher's page; dimensions are facts
507movements.comBrown's movement No. 8: figure, his text and an animationwebPublisher's page; dimensions are facts

Free files

★ Free files 1 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json

stepped-cone-pulleys-mechanism-assemblyAssembled mechanism, all parts placed at one pose (STEP keeps each part separate)STEP · STL
Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.
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Plain text: sheet.txt · JSON: /api/geometry?object=stepped-cone-pulleys-mechanism

Stepped cone pulleys (three speeds by moving the belt), isometric render of a generated part
Render of stepped-cone-pulleys-mechanism-assembly from the free STEP; not to scale.

Fits with

Stepped (speed-cone) pulley Ø50 / Ø40 / Ø30 × 20 mm steps, Ø8 bore, isometric render of a generated part
Stepped (speed-cone) pulley Ø50 / Ø40 / Ø30 × 20 mm steps, Ø8 bore50.0×50.0×60.0 mm★ 1 file
Flat belt 16 × 1.5 for two Ø40 pulleys at 120 mm (loop drawn on the pulleys), isometric render of a generated part
Flat belt 16 × 1.5 for two Ø40 pulleys at 120 mm (loop drawn on the pulleys)163.0×43.0×16.0 mm★ 1 file

Questions

How do stepped cone pulleys change speed?

Two identical stepped pulleys mounted head to tail: moving the belt from one step pair to another changes the speed ratio — 50/30 = 1.67, 40/40 = 1, 30/50 = 0.6 — while the belt length stays the same because each pair's diameters add to 80 mm.