Double-action pump

The utility model relates to a double-action pump, and belongs to the technical field of liquid pumps. The double-action pump is characterized in that a liquid discharge pipe and a liquid inlet pipe are arranged on a pump head. A liquid inlet and discharge valve assembly is installed in the pump head. A first hydraulic cavity is arranged below the liquid inlet and discharge valve assembly. A primary seal casing body is installed on one side of the pump head. An auxiliary seal casing body is connected in the primary seal casing body in a sleeved mode. A plunger is arranged in the primary seal casing body. The front end of the plunger is placed in the first hydraulic cavity, and the rear end of the plunger is placed in the auxiliary seal casing body. A main padding is arranged in the middle portion of the plunger, and an auxiliary padding is arranged in the back portion of the plunger. A space encircled by the plunger, the main padding, the auxiliary padding and the auxiliary seal casing body is a second hydraulic cavity. A first flow channel is arranged in the primary seal casing body, and is communicated with the second hydraulic cavity. A crosshead, a connecting rod and a crankshaft are connected with the rear end of the plunger in sequence. A double-acting working manner is adopted when the double-action pump transports high pressure liquid, operating efficiency of the pump is improved, and workload of installation and maintenance of a worker is reduced.