The Structure of Mechanisms

The structure of a mechanism is its composition, its classification, and the conditions in which motion is transmitted in a predeterminate way. The variety and the complexity of technical systems gives a requirement for conventional representations of the elements of mechanisms and the linkages between them, and the establishment of certain rules for their representation, formation and decomposition. This chapter discusses kinematic elements, kinematic pairs, kinematic chains, and mobility of mechanisms. The component parts of mechanisms that have motions relative to one another are called the kinematic elements of the mechanisms. The direct and permanent link between two elements is called a kinematic pair. The system of elements jointed by kinematic links is called a kinematic chain. The mechanism is the kinematic chain having one fixed element and in which all the elements have predeterminate motions. According to their functional role, the component elements of the mechanism can be driving or driven.