How to exchange centric inverted slider cranks with λ-formed four-bar linkages

Each symmetrical coupler-branch produced by a coupler point of the slider of an inverted slider crank is to be reproduced by the coupler point of a different, λ-formed four-bar linkage. The reproduction of the coupler-branch by these branch-cognates appears to be a very good approximation of the original curve. Formulas for their derivation are presented for the crank-and-rocker type as well as for the double crank type of mechanism. The method replaces the roll-slide by an ordinary turning-joint of the frame.