Synthesis of Spatial Four-Bar Mechanisms : Part I, Classification of Mechanisms and Synthesis of a Mechanism with Two Revolute Pairs, One Cylindric pair and One Spheric Pair

Abstract

Spatial four-bar mechanisms are studied with the purpose of utilizing them as generators of functions with one variable. In Part I, the moving closed circuits are first described in connection with the degrees of freedom of spatial mechanisms, and then a number synthesis is made to result in 95 kinds of mechanisms having a single degree of freedom between the driving and driven links. Among them are included many mechanisms whose total number of degrees of freedom is not one. The mechanisms are limited to ones composed of practical pairs, i.e., revolute, prismatic, cylindric, spheric and sphere-groove pairs. A dimensional synthesis is also made with three precision points for a mechanism with two revolute pairs, one cylindric pair and one spheric pair. The equations of the synthesis are given in the form convenient for programming of electronic digital computers.