Abstract: To cam mechanisms with roller follower moving in general planar motion, the concepts of “special and general type II mechanisms synthesis tasks” are put forward, and the scientific and exact description is brought. Via establishment of coordinate system, introduction of “floating coordinate system” and division of front and rear work travel, especially the introductions of new concepts of “instantaneous choice area” and “whole choice area”, the new graphic fundamental for solving “instantaneous choice area” of roller-center as well as deep analysis of boundary are brought out. The concepts of “most commercial search belt-area” and important thinking of eqisdistance-dispersion are given. Dimensionality-drop rapid solving algorithm is given, which satisfactorily solves “general type II mechanisms synthesis task”.

Key words: Dimensionality-drop, Equidistance-dispersion, Floating coordinate system, Instantaneous/whole choice area, Most commercial search belt-are, Special/general