In a gear pump, how does liquid move through the pump?

• A. It flows through a diaphragm
• B. It is drawn by a piston
• C. It enters the space between the teeth of two gears and moves around the casing to the outlet
• D. It is sucked through a valve

Answer: (C)

Gear pumps move liquid through positive displacement by trapping it in pockets formed between the gear teeth and the surrounding chamber. As the gears rotate, these pockets between the meshing teeth and the housing are carried around the outside of the gears from the suction side to the discharge side. When the pocket reaches the outlet, the liquid is forced out, creating flow. The description that liquid enters the space between the teeth of two gears and moves around the casing to the outlet captures this trapping and transport mechanism inside the pump. This is distinct from diaphragm, piston, or valve-driven methods, which do not describe how an external gear pump actually traps and transfers the fluid.