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Slider-crank mechanism (crank and connecting rod)

How does a slider-crank turn rotation into straight-line motion? · Hardware · basis: Xem Studio drawing; classic mechanism (Brown No. 92)

Also called: slider crank, crank and slider, crank connecting rod mechanism, slider crank 3d print, mecanismo biela manivela, Schubkurbel, système bielle manivelle

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

sizes
5 in table

Notes

  • A crank of radius r drives a connecting rod of length L whose other end slides on a line through the crank centre. Stroke = 2r (40 mm here).
  • Slider position x = r·cosθ + √(L² − r²·sin²θ); the rod ratio L/r (4 here) sets how far the motion departs from simple harmonic.
  • It is the piston-engine and pump layout; running backwards (slider drives) it needs a flywheel to pass the dead centres.
  • Parts (each has its own page): crank-discs-5mm-bore, connecting-rods-623, crosshead-8mm, crosshead-guide-8mm, pins-3mm. Brown's movement No. 92 shows it (1868).

Slider-crank mechanism size chart

parametervalue
crank radius r20 mm
rod length L80 mm
stroke40 mm
pinsØ3
shaftØ5

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

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

slider-crank-mechanism-assemblyAssembled mechanism, all parts placed (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=slider-crank-mechanism

Slider-crank mechanism (crank and connecting rod), isometric render of a generated part
Render of slider-crank-mechanism-assembly from the free STEP; not to scale.

Fits with

Crank discs for a Ø5 shaft, 10 to 30 mm stroke, isometric render of a generated part
Crank discs for a Ø5 shaft, 10 to 30 mm stroke5 sizes★ 5 files
Connecting rods 30 to 80 mm centres with 623 pockets, isometric render of a generated part
Connecting rods 30 to 80 mm centres with 623 pockets5 sizes★ 5 files
Crosshead Ø8 × 24 for a Ø3 piston rod, isometric render of a generated part
Crosshead Ø8 × 24 for a Ø3 piston rod4 sizes★ 1 file
Crosshead guide, Ø8 bore × 30, isometric render of a generated part
Crosshead guide, Ø8 bore × 305 sizes★ 1 file
Crank and wrist pins Ø3 × 12, 16, 19, 20 and 23, isometric render of a generated part
Crank and wrist pins Ø3 × 12, 16, 19, 20 and 235 sizes★ 5 files

Questions

How does a slider-crank turn rotation into straight-line motion?

A crank of radius r drives a connecting rod of length L whose other end slides on a line through the crank centre. Stroke = 2r (40 mm here).