Plunger pump belongs to positive displacement pump, reciprocating pump. The piston pump moves back and forth through the plunger in the cylinder, resulting in the pressure difference caused by the change of seal volume in the cylinder, which makes the fluid medium work. Change the plunger stroke to control the volume of the plunger pump. Plunger pump is an important working part in hydraulic and pneumatic transmission. Common plunger pump is divided into radial piston pump, axial piston pump.