Center deflection locking hydraulic cylinder

The invention discloses a center deflection locking hydraulic cylinder. The center deflection locking hydraulic cylinder comprises a cylinder body, a piston rod assembly and a positioning cone; the piston rod assembly is assembled with the cylinder body by a guide sleeve; the end part of the piston rod assembly is connected with the positioning cone; a thread hole and an empty cutter groove are formed in the end part of the piston rod assembly; the empty cutter groove is connected to the inner end surface of the thread hole; the positioning cone includes a cone part and a conical head part; the conical head part is a step-shaped cylinder, and includes a large step part, a transition part and a small step part with a thread, which are connected in sequence; the small step part with the thread extends into the empty cutter groove by the thread hole; the end surface of the small step part is a spherical surface contacted with the bottom of the empty cutter groove; and the small step part and the empty cutter gro