The
plunger pump comprises a pump body, a high-pressure cavity, a low-pressure cavity and a pressure regulating valve, the high-pressure cavity, the low-pressure cavity and the pressure regulating valve are arranged in the pump body, a mounting part is arranged on one side of the pump body, a mounting groove is formed in the mounting part, a first flow channel and a second flow channel are formed in the side wall of the mounting groove, the first flow channel is communicated with the low-pressure cavity, and the second flow channel is communicated with the low-pressure cavity. The runner II is communicated with the high-pressure cavity; a
choke plug is inserted in the mounting groove, and a first circulation groove and a second circulation groove are formed in the
choke plug. A
steel ball is arranged in the first circulation groove, a supporting ring is arranged in the mounting groove, a placing ring groove is formed in the position, corresponding to an inlet of the first flow channel, of the bottom of the mounting groove, a spring is placed in the placing ring groove, the spring penetrates through an inner hole of the supporting ring and extends into the first circulation groove, and the top end of the spring abuts against the
steel ball. The low-load soft start circuit can realize low-load soft start.