Over-tightening protective shear ring locking mechanism

The invention relates to an over-tightening protective shear ring locking mechanism. The over-tightening protective shear ring locking mechanism comprises a positioning plate, at least four compressing blocks, reset springs and elastic positioning blocks, wherein the positioning plate is cylindrical, and a positioning groove is formed in the inner surface of the positioning plate; the compressing blocks are connected with the positioning groove in a sliding mode; the elastic positioning blocks are respectively arranged between the inner surface of the positioning groove and the outer surfaces of the compressing blocks as well as between the contact surfaces of adjacent compressing blocks; a connecting screw hole is formed in the middle point of the outer surface of each compressing block; at least one mounting hole is respectively formed in the two sides of each connecting screw hole; connecting screw holes and mounting holes are also respectively formed in the positions, corresponding to the connecting screws and the mounting holes, of the positioning groove; a driving screw rod is arranged in each compressing block through the corresponding connecting screw hole; the reset springs are mounted in the mounting holes; connecting blocks are additionally arranged on the upper end face and the lower end face of the positioning plate. On one hand, constant clamping force and good sealing capacity can be provided for axle and shaft parts, and on the other hand, the structures of the alxe and shaft parts can be effectively prevented from being damaged by too large clamping force while the alxe and shaft parts are clamped.