A gear pump is a rotary pump that relies on the variation and movement of the working volume between the pump cylinder and the meshing gears to transport liquid or increase pressure. Two enclosed spaces are formed by 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, and the liquid is squeezed into the pipeline. The suction and discharge chambers are separated by the meshing lines of two gears. The pressure at the discharge port of a gear pump depends entirely on the magnitude of the resistance at the pump outlet.