What do you know about hydraulic gear pumps?

Gear pump is a rotary pump that relies on the change and movement of working volume formed between pump cylinder and meshing gear to transport liquid or pressurize it. 

Two closed 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, sucking the liquid, and the volume of the space on the engaged side of the gears decreases from large to small, thus squeezing the liquid into the pipeline.

The suction chamber and the discharge chamber are separated by the meshing line of two gears. The pressure at the outlet of the gear pump depends entirely on the resistance at the pump outlet.