Abstract: Heavy-duty forging manipulators play an important role in the extreme manufacturing. Decoupling performance of major-motion mechanism for three commonly used forging manipulators is studied to simplify the control of manipulators. The kinematics of the forging manipulators are analyzed, and the input-output relationship matrix in terms of velocity shows that all the three types of forging manipulators are coupled according to the definition of conventional output parameters. A new decoupling concept is established, which redefines the output based on the realistic working condition. The input-output relationships are considered independently for each main motion, and the process is simulated in Matlab to validate the results. The major-motion mechanism of one forging manipulator is decoupled, while the other two are partially decoupled. From the viewpoint of decoupling of the main-motion mechanism of forging manipulators, the proposed method is intuitive, which provides a new idea for the decoupling of parallel mechanisms

Key words: Decupling, Forging manipulator, Major-motion, Parallel mechanism