In the course of designing crank and rocker mechanism

the value of polar-place included angle

rocker swing angle will have an influence on the performance of force-transfering. The passibility depends on the scope within which hinge center A is setted

Computer sofetwares was applied to analyse the relation between polar-place included angle

rocker swing angle and scope of center settling. If the rocker swing angle remains unchage with in increasing of value θ

the scope hinge center will reduce. When θ>θ max

the Δt will cut down to zero

and the mechanism can not meet demands of force-transfering. If Φ changes

θ max will change. The researches provided a theoretical foundation for the design of crank and rocker mechanism.