Parker gear pump is a rotary pump that transports liquid or pressurizes it by relying on the variation and movement of the working volume formed between the pump cylinder and the meshing gear. Two enclosed spaces are composed of two gears, the pump body, and the front and rear covers. When the gears rotate, the volume of the space on the disengaged side of the gears increases from small to large, forming a vacuum that sucks in the liquid. The volume of the space on the meshing side of the gears decreases from large to small, squeezing the liquid into the pipeline. The suction chamber and discharge chamber are separated by the meshing line of two gears. The pressure at the discharge port of the Parker gear pump completely depends on the resistance at the pump outlet.