Hydraulic drive can be defined as a set of technical functions through which the transmission of mechanical energy is carried out, from a driver element to a driven one, using a hydraulic environment. Hydraulic pumps are hydrostatic, flow-generating, wide-use power generation machines that receive mechanical energy produced by a force machine and convert it into hydrostatic energy, which imprints it to the hydraulic working environment. In the paper, the graphic modeling of two different types of hydraulic pumps is performed, a gear pump and an axial piston pump, as well as a calculation that highlights the value differences of flow, moment and hydraulic power of the two types of pumps.