Peaucellier–Lipkin Linkage

The Peaucellier–Lipkin linkage (1864) was the first planar linkage that converts circular motion into exact straight-line motion. Adjust the lengths below and watch the straight line traced by the point P′ (red). You can also drag the driving point P. See the post Peaucellier–Lipkin Linkage for an explanation of how it works.