Pump core of plunger pump for centralized lubricating oil pump

A plunger pump core for a centralized lubricating oil pump comprises a pump core shell, a piston rod, a valve core and a limiting nut, the limiting nut is screwed in an inner hole of the pump core shell, one end of the piston rod extends into the inner hole of the pump core shell in the axial direction, and the valve core is located in the inner hole of the pump core shell and located between the limiting nut and the piston rod. A valve element spring is arranged between the limiting nut and the valve element, the piston rod can reciprocate between the retraction position away from the limiting nut and the stretching position close to the limiting nut, an oil inlet hole is formed in the side wall of the pump element shell, and an axial through hole is formed in the limiting nut. According to the utility model, the positioning error of the valve core spring can be ensured only by tightening the limiting nut, the process is simple, the operation is convenient, the mounting length of the valve core spring can be