How does a gear pump use rotating gear teeth to move fluid?

A gear pump is a type of rotary positive displacement pump that utilizes two meshing gears to move fluid through a casing.12

The process functions as follows:

• Intake: As the gears rotate and unmesh, a partial vacuum is created, which draws fluid into the pump.2
• Transfer: The fluid is trapped between the rotating gear teeth and the fixed casing, where it is carried from the inlet side to the outlet side of the pump.12
• Discharge: As the gear teeth mesh together again, the available volume decreases, generating an increase in pressure that forces the fluid into the outlet line.2

Because these pumps rely on the fluid itself to lubricate internal moving parts, they are generally not suitable for pumping gases or liquids containing solid particles, which can cause clogging or wear. However, they are highly effective for moving very viscous liquids because they do not require check valves.2