---
jupyter:
  description: 'Mechanism examples with planex2d in Python: four-bar and straight-line linkages, the Jansen leg,
    a hood hinge, Geneva and cycloidal drives, belt drives, Ackermann steering, the slider-crank, bicycle tracks
    and the haberdasher''s puzzle.'
---

# Mechanism examples

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- [Four-bar linkage](four-bar-linkage.md)
- [Hood hinge](hood-hinge.md)
- [Jansen linkage](jansen-linkage.md)
- [Straight-line linkages](straight-line-linkages.md)
- [Geneva drive](geneva-drive.md)
- [Cycloidal drive](cycloidal-drive.md)
- [Belt drives](belt-drives.md)
- [Drilling a square hole](square-hole.md)
- [The haberdasher's puzzle](haberdasher.md)
- [Bicycle tracks](bicycle-tracks.md)
- [Ackermann steering](ackermann-steering.md)
- [The slider-crank and the Scotch yoke](slider-crank.md)
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These examples are linkages and drives, and their geometry follows from their motion. A linkage is drawn once for
every crank angle, either from the circles its links can reach or as a constraint sketch in which the crank angle is
a driving dimension, and its positions give the coupler curves, the strokes and the accelerations. A part that the
motion cuts, as the disc of a cycloidal drive or the locking disc of a Geneva drive, is the blank minus the cutter in
every position.

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<a class="px-card" href="four-bar-linkage.html"><div class="thumb"><img src="../_static/gallery/four-bar-linkage.gif" alt="Four-bar linkage"></div><b>Four-bar linkage</b><span>A crank-rocker and its coupler curve through 72 positions.</span></a>
<a class="px-card" href="hood-hinge.html"><div class="thumb"><img src="../_static/gallery/hood-hinge.gif" alt="Hood hinge"></div><b>Hood hinge</b><span>Three-position synthesis in a constraint sketch, checked against the textbook.</span></a>
<a class="px-card" href="jansen-linkage.html"><div class="thumb"><img src="../_static/sections/constraints/jansen.gif" alt="Jansen linkage"></div><b>Jansen linkage</b><span>The Strandbeest leg with eleven links on one crank and the foot&#x27;s flat step.</span></a>
<a class="px-card" href="straight-line-linkages.html"><div class="thumb"><img src="../_static/gallery/straight-line-linkages.gif" alt="Straight-line linkages"></div><b>Straight-line linkages</b><span>Watt, Chebyshev and the exact Peaucellier-Lipkin linkage.</span></a>
<a class="px-card" href="geneva-drive.html"><div class="thumb"><img src="../_static/gallery/geneva-drive.gif" alt="Geneva drive"></div><b>Geneva drive</b><span>A quarter turn per revolution, with the locking disc cut by what the wheel sweeps.</span></a>
<a class="px-card" href="cycloidal-drive.html"><div class="thumb"><img src="../_static/gallery/cycloidal-drive.gif" alt="Cycloidal drive"></div><b>Cycloidal drive</b><span>The disc cut by every ring pin at every crank angle.</span></a>
<a class="px-card" href="belt-drives.html"><div class="thumb"><img src="../_static/gallery/belt-drives.png" alt="Belt drives"></div><b>Belt drives</b><span>The belt length as one expression, with the pulley and tensioner placed by the solver.</span></a>
<a class="px-card" href="square-hole.html"><div class="thumb"><img src="../_static/gallery/square-hole.gif" alt="Drilling a square hole"></div><b>Drilling a square hole</b><span>A Reuleaux triangle covers about 98.77 % of the square.</span></a>
<a class="px-card" href="haberdasher.html"><div class="thumb"><img src="../_static/gallery/haberdasher.gif" alt="The haberdasher&#x27;s puzzle"></div><b>The haberdasher&#x27;s puzzle</b><span>A triangle in four hinged pieces swung by one angle into a square, without collision.</span></a>
<a class="px-card" href="bicycle-tracks.html"><div class="thumb"><img src="../_static/gallery/bicycle-tracks.gif" alt="Bicycle tracks"></div><b>Bicycle tracks</b><span>Once around any loop, the tracks of the two wheels enclose areas that differ by exactly πL².</span></a>
<a class="px-card" href="ackermann-steering.html"><div class="thumb"><img src="../_static/gallery/ackermann-steering.png" alt="Ackermann steering"></div><b>Ackermann steering</b><span>A steering trapezoid in a constraint sketch against the Ackermann condition, and the arm angle that comes closest.</span></a>
<a class="px-card" href="slider-crank.html"><div class="thumb"><img src="../_static/gallery/slider-crank.gif" alt="The slider-crank and the Scotch yoke"></div><b>The slider-crank and the Scotch yoke</b><span>A piston against a pure cosine: the rod&#x27;s second harmonic and the accelerations at the top and bottom, from a sketch.</span></a>
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See [Examples](index.md) for the other collections.