Chebyshev linkage

In kinematics, Chebyshev's linkage is a four-bar linkage that converts rotational motion to approximate linear motion.

It was invented by the 19th-century mathematician Pafnuty Chebyshev, who studied theoretical problems in kinematic mechanisms. One of the problems was the construction of a linkage that converts a rotary motion into an approximate straight-line motion (a straight line mechanism). This was also studied by James Watt in his improvements to the steam engine, which resulted in Watt's linkage.