The gear pump definition is, it is a PD (positive displacement) rotating pump which assists you to move water otherwise fluid with the help of inbuilt gears. This type of pump includes two or more gears that create vacuum force to drive the liquid within the pump. This pump can be built with different parts like shaft, rotors, and casing. These pumps have high-pressure and are available in tiny sizes to supply constant liquid flow & a pulseless as contrasted to other types of pumps such as diaphragm & peristaltic pumps.
http://www.oilmaxhydraulic.com/gear-pumps/