A modification of Peaucellier linkage proposed in 1877 by A. B. Kempe, London.

Length of blue bar: a

Length of pink bar of 3 joints: 0.25a + 0.75a

Length of yellow bars: 0.5a

Length of orange bars: 0.25a

Axle distance between the three fixed revolution joints 0.25a + 0.75a

The pink bar moves along an absolutely straight line.