Limit unloading hydraulic nut

The utility model relates to a limit unloading hydraulic nut, which comprises a swivel nut, a cylinder body and a piston, wherein the outer diameter of the piston is provided with a stepped wall surface, and the inner diameter of the piston is in a screw structure; an oil injection hole channel is arranged at the upper end of the piston along the axial direction; the cylinder body is coaxially sleeved outside the piston; the inner wall of the cylinder body is provided with a stepped wall surface tightly matched with the piston, and an oil injection hole is formed in the side surface; the swivel nut is sleeved at the upper end of the piston; an oil leakage through hole is formed in the pipe wall of the cylinder body at the position with an Lmax distance (maximum limit distance) to the stepped surface of the piston; a limit valve consisting of a ball valve core, a spring and an adjusting screw nail is arranged inside the through hole; and a damping hole communicated with the outside of the nut is formed in the