Gear pumps are a type of positive displacement pump that use the meshing of gears to move fluids. They consist of two or more gears that rotate within a casing, creating a vacuum that draws fluid into the pump and then pushes it out. Gear pumps are commonly used in various applications, including hydraulic systems and fuel transfer, due to their efficiency and ability to handle high-viscosity fluids. These pumps can be classified into two main types: external gear pumps and internal gear pumps. External gear pumps have two gears that rotate outside each other, while internal gear pumps have one gear inside another. Both types are known for their reliability and consistent flow rates, making them suitable for industrial and automotive applications.