Gear pumps are positive displacement (or fixed displacement), meaning they pump a constant amount of fluid for each revolution. Some gear pumps are designed to function as either a motor or a pump.

An external precision gear pump is usually limited to a maximum working pressure of 210 bars (21,000 kPa) and a maximum speed of 3,000 rpm. Some manufacturers produce gear pumps with higher working pressures and speeds but these types of pumps tend to be noisy and special precautions may have to be made.