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Two speeds by shifting a belt between pulleys carrying gears (20 / 40 T)

How does shifting a belt between two pulley-gear units give two speeds? · Hardware · basis: Xem Studio design following Brown No. 59 (1868)

Also called: two speed belt gear, belt shifted gears, speed change, dos velocidades con correa y engranajes, Zweigang mit Riemen und Zahnrädern

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

sizes
4 in table

Notes

  • Two loose units on the input shaft, each a pulley with a gear (20 and 40 teeth), mesh with a 40 / 20 cluster on the output shaft. The belt on the 20-tooth unit's pulley gives the output half the pulley's speed; shifted onto the 40-tooth unit, twice — the unit not driven just idles.
  • Module 1, 30 mm centres; belt from a wide Ø40 driving pulley 140 mm above, drawn on the 20-tooth unit.
  • Brown's No. 59 (two speeds from a belt shifted between pulleys carrying small and large gears).
  • Parts (each has its own page): pulley-gear-unit-40-m1-20t-bore8, pulley-gear-unit-40-m1-40t-bore8, gear-cluster-m1-40-20-bore8, plain-flat-pulley-40x66, flat-belt-16x1-5-pulleys-40-40-c140, linear-shafts-h6.
  • Brown's movement No. 59 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

Two speeds by shifting a belt between pulleys carrying gears size chart

parametervalue
unitsØ40 pulleys with 20 / 40 T gears
cluster40 / 20 T
speeds0.5, 2 × input
centres30 mm

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. 59: figure, his text and an animationwebPublisher's page; dimensions are facts

Free files

★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json

belt-shifted-gears-two-speed-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=belt-shifted-gears-two-speed-mechanism

Two speeds by shifting a belt between pulleys carrying gears (20 / 40 T), isometric render of a generated part
Render of belt-shifted-gears-two-speed-mechanism-assembly from the free STEP; not to scale.

Fits with

Pulley and gear unit: Ø40 × 16 flat pulley with a module 1, 20-tooth gear, Ø8 bore, isometric render of a generated part
Pulley and gear unit: Ø40 × 16 flat pulley with a module 1, 20-tooth gear, Ø8 bore40.0×40.0×24.0 mm★ 1 file
Pulley and gear unit: Ø40 × 16 flat pulley with a module 1, 40-tooth gear, Ø8 bore, isometric render of a generated part
Pulley and gear unit: Ø40 × 16 flat pulley with a module 1, 40-tooth gear, Ø8 bore41.99×41.99×24.0 mm★ 1 file
Gear cluster, module 1: 40 T / 20 T on one Ø14 hub, Ø8 bore, isometric render of a generated part
Gear cluster, module 1: 40 T / 20 T on one Ø14 hub, Ø8 bore41.99×41.99×33.0 mm★ 1 file
Plain flat-belt pulley Ø40 × 66 face, Ø8 bore (no flanges), isometric render of a generated part
Plain flat-belt pulley Ø40 × 66 face, Ø8 bore (no flanges)40.0×40.0×66.0 mm★ 1 file
Flat belt 16 × 1.5 for two Ø40 pulleys at 140 mm (loop drawn), isometric render of a generated part
Flat belt 16 × 1.5 for two Ø40 pulleys at 140 mm (loop drawn)43.0×183.0×16.0 mm★ 1 file
Linear shafts Ø3 to Ø25 mm (h6), 100 to 1000 mm long, isometric render of a generated part
Linear shafts Ø3 to Ø25 mm (h6), 100 to 1000 mm long10 sizes★ 70 files

Questions

How does shifting a belt between two pulley-gear units give two speeds?

Two loose units on the input shaft, each a pulley with a gear (20 and 40 teeth), mesh with a 40 / 20 cluster on the output shaft. The belt on the 20-tooth unit's pulley gives the output half the pulley's speed; shifted onto the 40-tooth unit, twice — the unit not driven just idles.