Xem Studiomeasured geometry

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Bell-crank lever turning a pull through 90°

What does a bell crank do? · Hardware · basis: Xem Studio design following Brown No. 126 (1868)

Also called: bell crank, bell crank lever, angle lever, palanca acodada, Winkelhebel

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

sizes
4 in table

Notes

  • An L-shaped lever on a pivot at its corner: a pull on one arm becomes a pull at right angles on the other. Force ratio = arm lengths (1 : 1 for 30 × 30 mm; the 20 × 40 crank gives 2 : 1).
  • Here the catalog 30 × 30 bell crank turns on a 623 bearing pressed in its Ø10 pocket, with 60 mm links on each arm.
  • Brown's No. 126; used in bell-pulls, control rods and brakes to change the direction of a push or pull.
  • Parts (each has its own page): bell-cranks, ball-bearings-metric, four-bar-links, dowel-pins-metric.
  • Brown's movement No. 126 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

Bell-crank lever turning a pull through 90° size chart

parametervalue
arms30 × 30 mm at 90°
pivot623 bearing on Ø3 pin
links2 × 60 mm
ratio1 : 1

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. 126: 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

bell-crank-lever-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=bell-crank-lever-mechanism

Bell-crank lever turning a pull through 90°, isometric render of a generated part
Render of bell-crank-lever-mechanism-assembly from the free STEP; not to scale.

Fits with

Bell cranks: 30 × 30 and 20 × 40 mm arms at 90°, isometric render of a generated part
Bell cranks: 30 × 30 and 20 × 40 mm arms at 90°2 sizes★ 2 files
Ball bearings, 683 to 6210 and flanged F6xx (ISO 15), isometric render of a generated part
Ball bearings, 683 to 6210 and flanged F6xx (ISO 15)44 sizes★ 44 files
Four-bar links: flat links with 20 to 100 mm hole centres, isometric render of a generated part
Four-bar links: flat links with 20 to 100 mm hole centres7 sizes★ 7 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

What does a bell crank do?

An L-shaped lever on a pivot at its corner: a pull on one arm becomes a pull at right angles on the other. Force ratio = arm lengths (1 : 1 for 30 × 30 mm; the 20 × 40 crank gives 2 : 1).