Xem Studiomeasured geometry

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Weighted belt tightener: pulley on a slide pulled by a hanging weight

How does a weighted tightener keep a belt tight? · Hardware · basis: Xem Studio design following Brown No. 23 (1868)

Also called: belt tensioner, weighted tensioner, gravity belt tensioner, constant tension belt, tensor de correa con contrapeso, Riemenspanner mit Gewicht

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

sizes
4 in table

Notes

  • The driven pulley turns on a slide that runs on guide rods; a weight hung from the slide pulls it away from the driver, so the belt stays at the same tension however it stretches.
  • Belt tension ≈ half the weight's pull per strand: a 394.58 g steel weight gives about 1.94 N in each strand. Here Ø80 driver over a Ø40 pulley 150 mm below, 16 × 1.5 belt of 491.17 mm.
  • Brown's No. 23 (hanging, weighted tightener on a sliding frame).
  • Parts (each has its own page): flanged-flat-pulley-40, flanged-flat-pulley-80, flat-belt-16x1-5-pulleys-40-80-c150, tightener-slide-8mm-stub, hanging-weight-d40x40-lug, linear-shafts-h6, dowel-pins-metric.
  • Brown's movement No. 23 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

Weighted belt tightener: pulley on a slide pulled by a hanging weight size chart

parametervalue
pulleysØ80 above Ø40, 150 mm
slide60 × 20 × 10 on 2 × Ø6 rods
weightØ40 × 40 (394.58 g steel)
belt16 × 1.5, 491.17 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. 23: 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

weighted-belt-tightener-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=weighted-belt-tightener-mechanism

Weighted belt tightener: pulley on a slide pulled by a hanging weight, isometric render of a generated part
Render of weighted-belt-tightener-mechanism-assembly from the free STEP; not to scale.

Fits with

Flanged flat-belt pulley Ø40, 16 mm face, Ø8 bore, isometric render of a generated part
Flanged flat-belt pulley Ø40, 16 mm face, Ø8 bore46.0×46.0×20.0 mm★ 1 file
Flanged flat-belt pulley Ø80, 16 mm face, Ø8 bore, isometric render of a generated part
Flanged flat-belt pulley Ø80, 16 mm face, Ø8 bore86.0×86.0×20.0 mm★ 1 file
Flat belt 16 × 1.5 for Ø40 and Ø80 pulleys at 150 mm (loop drawn on the pulleys), isometric render of a generated part
Flat belt 16 × 1.5 for Ø40 and Ø80 pulleys at 150 mm (loop drawn on the pulleys)83.0×213.0×16.0 mm★ 1 file
Tightener slide 60 × 20 × 10 with Ø8 stub axle, two Ø6 rod bores and a pin tab, isometric render of a generated part
Tightener slide 60 × 20 × 10 with Ø8 stub axle, two Ø6 rod bores and a pin tab60.0×46.0×31.0 mm★ 1 file
Hanging weight Ø40 × 40 with a pin lug (394.58 g in steel), isometric render of a generated part
Hanging weight Ø40 × 40 with a pin lug (394.58 g in steel)40.0×40.0×52.0 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
Dowel pins, 2–6 mm (ISO 2338 / DIN 6325), isometric render of a generated part
Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)5 sizes★ 23 files

Questions

How does a weighted tightener keep a belt tight?

The driven pulley turns on a slide that runs on guide rods; a weight hung from the slide pulls it away from the driver, so the belt stays at the same tension however it stretches.