Retrieval function is very important in operation of pipeline inspection robot to remove the possibility of being stuck inside pipelines. This paper presents synthesis of linkage type mechanical clutches (LMC) which are used for retrieving pipeline inspection robots. Initially, the working principle of LMC is described and 5 types of LMC is suggested, which can be used for pipelines with its diameter less than 100mm. Through simulation and experimentation, feasibility of LMC is verified.