Chebyshev linkage

From Wikipedia, the free encyclopedia

The Chebyshev linkage is a four bar mechanism that converts rotational motion to approximate straight-line motion. The crossed links AB and CD are equal in length. The tracing point P is situated at the midpoint of the link BC. The proportions of the links are usually such that P is directly above A or D in the extreme positions of the mechanism, i.e. when CB lies along AB or when CB lies along CD. It can easily be shown that in these circumstances the tracing point P will lie on a straight line parallel to AD in the two extreme positions and in the mid position if BC : AD : AB :: 1 : 2 : 2.5