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Three speeds by shifting a belt over pulleys carrying gears (16 / 24 / 32 T)

How does shifting a belt along pulley-gear units give three speeds? · Hardware · basis: Xem Studio design following Brown No. 58 (1868)

Also called: three speed belt gear, gear change by belt, pulley gear speed change, tres velocidades con correa y engranajes, Dreigang mit Riemen und Zahnrädern

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

sizes
4 in table

Notes

  • On the input shaft run loose units each made of a pulley and a gear (16, 24 and 32 teeth) and an idle pulley; the gears mesh with a cluster of 32, 24 and 16 teeth fixed on the output shaft 30 mm away. The belt drives whichever unit it is on: output speed 16/32, 24/24 or 32/16 of the input pulley's — or nothing on the idler.
  • Module 1.25 throughout (N₁ + N₂ = 48 keeps one 30 mm centre distance); belt from a wide Ø40 driving pulley 140 mm above, drawn on the 24-tooth unit (1 : 1). Speeds: 0.5, 1, 2 × input.
  • Brown's No. 58 (three speeds from a belt shifted across four pulleys carrying spur gears).
  • Parts (each has its own page): pulley-gear-unit-40-m1-25-16t-bore8, pulley-gear-unit-40-m1-25-24t-bore8, pulley-gear-unit-40-m1-25-32t-bore8, gear-cluster-m1-25-32-24-16-bore8, plain-flat-pulley-40x16, plain-flat-pulley-40x100, flat-belt-16x1-5-pulleys-40-40-c140, linear-shafts-h6.
  • Brown's movement No. 58 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

Three speeds by shifting a belt over pulleys carrying gears size chart

parametervalue
unitsØ40 pulleys with 16 / 24 / 32 T gears, module 1.25
cluster32 / 24 / 16 T
speeds0.5, 1, 2 × input, or stop
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. 58: 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-three-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.
Set it up →

Plain text: sheet.txt · JSON: /api/geometry?object=belt-shifted-gears-three-speed-mechanism

Three speeds by shifting a belt over pulleys carrying gears (16 / 24 / 32 T), isometric render of a generated part
Render of belt-shifted-gears-three-speed-mechanism-assembly from the free STEP; not to scale.

Fits with

Pulley and gear unit: Ø40 × 16 flat pulley with a module 1.25, 16-tooth gear, Ø8 bore, isometric render of a generated part
Pulley and gear unit: Ø40 × 16 flat pulley with a module 1.25, 16-tooth gear, Ø8 bore40.0×40.0×24.0 mm★ 1 file
Pulley and gear unit: Ø40 × 16 flat pulley with a module 1.25, 24-tooth gear, Ø8 bore, isometric render of a generated part
Pulley and gear unit: Ø40 × 16 flat pulley with a module 1.25, 24-tooth gear, Ø8 bore40.0×40.0×24.0 mm★ 1 file
Pulley and gear unit: Ø40 × 16 flat pulley with a module 1.25, 32-tooth gear, Ø8 bore, isometric render of a generated part
Pulley and gear unit: Ø40 × 16 flat pulley with a module 1.25, 32-tooth gear, Ø8 bore42.49×42.49×24.0 mm★ 1 file
Gear cluster, module 1.25: 32 T / 24 T / 16 T on one Ø14 hub, Ø8 bore, isometric render of a generated part
Gear cluster, module 1.25: 32 T / 24 T / 16 T on one Ø14 hub, Ø8 bore42.49×42.49×58.0 mm★ 1 file
Plain flat-belt pulley Ø40 × 16 face, Ø8 bore (no flanges), isometric render of a generated part
Plain flat-belt pulley Ø40 × 16 face, Ø8 bore (no flanges)40.0×40.0×16.0 mm★ 1 file
Plain flat-belt pulley Ø40 × 100 face, Ø8 bore (no flanges), isometric render of a generated part
Plain flat-belt pulley Ø40 × 100 face, Ø8 bore (no flanges)40.0×40.0×100.0 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 along pulley-gear units give three speeds?

On the input shaft run loose units each made of a pulley and a gear (16, 24 and 32 teeth) and an idle pulley; the gears mesh with a cluster of 32, 24 and 16 teeth fixed on the output shaft 30 mm away. The belt drives whichever unit it is on: output speed 16/32, 24/24 or 32/16 of the input pulley's — or nothing on the idler.