Device for converting mechanical energy (torque M, rotation speed n) into hydraulic energy (flow rate Q, pressure p). Displacement pumps are used in hydrostatic applications for this purpose.
A flow rate emerges at the pressure connection of the pump and drives the hydraulic consumers (Hydraulic motor, Hydraulic cylinder). These convert the hydraulic energy back into mechanical energy.
Hydraulic pumps are mostly driven by electric drives or combustion engines.
Hydraulic pumps can be classified according to various aspects:
- Acted on from the outside or inside
- Constant or variable output volume (flow rate)
- Various displacement principles such as gear pumps with subcategories, vane pumps with subcategories, piston pumps, with subcategories

Construction forms of hydraulic pumps