Mechanisms　are　prone　to　stuttering　or　even　jamming　due　to　the　deformation　of　components,　especially　for　overconstrained　linkages　for　which　geometric　conditions　must　be　strictly　satisfied.　In　this　paper,　joint　clearance　is　actively　introduced　to　release　the　local　constraint　so　that　the　linkages　can　still　achieve　general　movement　under　the　deformation　of　components.　And　a　joint　clearance　model　with　a　revolute　joint　(R-joint)　is　built.　Based　on　the　model,　the　minimum　joint　clearance　introduced,　which　keeps　mechanisms　moving　smoothly,　is　found　when　the　components　of　the　linkages　have　a　certain　deformation.　The　correctness　of　the　proposed　method　is　verified　with　a　numerical　case,　and　the　optimal　position　for　clearance　introducing　is　analyzed.　It　opens　up　an　important　way　to　solve　the　phenomenon　of　stuttering　or　jamming　in　overconstrained　linkages.