Hydraulic pumps, which can be hydrostatic or hydrodynamic, are utilised in hydraulic drive systems. A hydraulic pump is a mechanical device that transforms mechanical energy into hydraulic energy (hydrostatic energy i.e. flow, pressure). It produces enough flow to overcome the pressure created by the load at the pump outlet. When a hydraulic pump is turned on, it creates a vacuum at the pump inlet, which forces liquid from the reservoir into the pump’s intake line, where it is delivered to the pump output and forced into the hydraulic system by mechanical action.

Hydrostatic pumps are positive displacement pumps, whereas hydrodynamic pumps can be fixed displacement pumps (flow through the pump per rotation of the pump) or variable displacement pumps (flow through the pump per rotation of the pump) with a more complicated construction that allows the displacement to be adjusted. In everyday life, hydrodynamic pumps are more common. Pascal’s law governs the operation of all types of hydrostatic pumps.