Xem Studiomeasured geometry

Library › Mechanisms › Linkages ·

Crank pin in a slotted bell crank

How does a crank rock a bell crank? · Hardware · basis: Xem Studio design following Brown No. 156 (1868)

Also called: slotted bell crank, crank and bell crank, oscillating bell crank, manivela en palanca acodada ranurada, Kurbel in geschlitztem Winkelhebel

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

sizes
4 in table

Notes

  • A crank pin, in a slide block, runs in a slot along one arm of a bell crank pivoted 70 mm from the crank centre: the bell crank rocks through ±9.87° (sin⁻¹ 12/70), with the quick-return timing of a slotted lever, and its second arm, 50 mm long at 90°, carries the motion off at a right angle.
  • Drawn at crank angle 200°: bell crank at 9.71°, output pin at (49.28, 8.43).
  • Brown's No. 156 (crank pin working in a slotted bell crank).
  • Parts (each has its own page): slotted-bell-crank-100-50-slot-50-90-b5, crank-disc-36-pin-r12, slide-block-12x6, dowel-pins-metric.
  • Brown's movement No. 156 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

Crank pin in a slotted bell crank size chart

parametervalue
crank radius12 mm
pivot distance70 mm
swing±9.87°
output arm50 mm at 90°

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. 156: 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

crank-slotted-bell-crank-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=crank-slotted-bell-crank-mechanism

Crank pin in a slotted bell crank, isometric render of a generated part
Render of crank-slotted-bell-crank-mechanism-assembly from the free STEP; not to scale.

Fits with

Slotted bell crank: 100 mm arm with a 6.4 slot (50–90 mm) and a 50 mm arm at 90°, Ø5 bore, isometric render of a generated part
Slotted bell crank: 100 mm arm with a 6.4 slot (50–90 mm) and a 50 mm arm at 90°, Ø5 bore64.0×115.0×8.0 mm★ 1 file
Crank disc Ø36 × 5, Ø5 bore, Ø3 pin hole at 12 mm, isometric render of a generated part
Crank disc Ø36 × 5, Ø5 bore, Ø3 pin hole at 12 mm36.0×36.0×5.0 mm★ 1 file
Slide block 12 × 6.2 mm for a 6.4 mm slot, isometric render of a generated part
Slide block 12 × 6.2 mm for a 6.4 mm slot2 sizes★ 1 file
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 crank rock a bell crank?

A crank pin, in a slide block, runs in a slot along one arm of a bell crank pivoted 70 mm from the crank centre: the bell crank rocks through ±9.87° (sin⁻¹ 12/70), with the quick-return timing of a slotted lever, and its second arm, 50 mm long at 90°, carries the motion off at a right angle.