Internal gear pumps are a type of positive displacement pump that use two gears to move fluid. One gear, called the rotor, is driven by a motor, while the other gear, known as the idler, rotates within the rotor. As the gears turn, they create a vacuum that draws fluid into the pump and then pushes it out through the discharge port. These pumps are commonly used in various applications, including hydraulic systems and lubrication systems, due to their ability to handle viscous fluids. Their design allows for smooth and consistent flow, making them efficient for transferring liquids like oil and other industrial fluids.