Kinematic Chains and Their Inversions:

In previous unit, you were introduced to kinematic pairs, degrees of freedom and links. In this unit, you will be described how to get different mechanisms by utilizing four bar chain that is a basic kinematic chain. The four bar chain contain four links that are linked with each other through the help of four lower kinematic pairs. This chain gives different mechanisms of common usage. For instance, one mechanism, provided by this, is utilized in petrol engine, steam engine, diesel engine, compressors, etc. One mechanism makes achievable to complete idle stroke in machine tool in lesser time than cutting stroke that reduces machining time. This mechanism being termed as rapid return mechanism. Likewise, there are some mechanisms that can provide rocking motion that can be used in materials handling.

Objectives

• After studying this unit, you must be able to
• know inversions of different kinematic chains,
• understand utility of several mechanisms of four bar kinematic chain,
• make kinematic design of a mechanism,
• evolve criteria for several mechanisms of 4R-kinematic chain, and
• Check movability of mechanism.