Triangular nomograms for symmetrical spherical non-Grashof double-rockers generating symmetrical coupler curves

This paper presents triangular nomograms for symmetrical spherical non-Grashof double-rockers generating symmetrical coupler curves, which provide a simple means to search for the desired symmetrical coupler curves. The dimensional parameters of a symmetrical spherical non-Grashof double-rocker are the lengths of the fixed link, turning link, coupler link, and coupler point position. Four types of symmetrical spherical non-Grashof double-rockers tracing symmetrical coupler curves are discussed. Seven kinds of special symmetrical coupler curves are investigated, and the corresponding geometric relations are used to derive the implicit equations consisting of four dimensional parameters. Then, four triangular nomograms for the symmetrical spherical non-Grashof double-rockers are presented for the determination of dimensional parameters of a linkage generating the desired curve without further calculation.