In connection with the phenomenon that the quality of products is affected seriously， because the connecting nut on the pillar of pillar flat vulcanizing machine is easy to loose， where no reliable connection， and the problem that lines between the flat are not parallel is often caused。In this paper, a kind of threaded connection to achieve reliable locking anywhere and benign dismountability is presented. The connection bases on ratchet wheel movement principle. The ratchet-shaped trench is designed on the contact surface of nut and gasket. The trench is circular uniform distribution and its axial section is triangular cone. This combination ensures that the fastening can be connected for the relative movement when the thread is rotated directly and for the self-locking when the thread is rotated reversely. The dismountability can be achieved by tilting the side wing of ratchet-gasket to remove the circumferential fix.