Gear pump

As the gears rotate they separate on the intake side of the pump, creating a void and suction which is filled by fluid.

The tight clearances, along with the speed of rotation, effectively prevent the fluid from leaking backwards.

Many variations exist, including helical and herringbone gear sets (instead of spur gears), lobe shaped rotors similar to Roots blowers (commonly used as superchargers), and mechanical designs that allow the stacking of pumps.

[3] Suction and pressure ports need to interface where the gears mesh (shown as dim gray lines in the internal pump images).

Factors affecting efficiency: The invention of the gear pump is not uniformly solved.