A modification of Peaucellier linkage proposed in 1877 by A. B. Kempe, London.
Length of blue bar: a
Length of green bar of 3 joints: 0.5a + 0.5a
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 0.75a + 0.25a
The pink bar moves along an absolutely straight line.