Type and function of hydraulic pumps
Hydraulic pumps convert provided mechanical energy into hydraulic energy and are available in various designs and sizes. They generate an almost continuous volume flow. Hydraulic pumps come in different types: gear pumps, radial piston pumps, axial piston pumps and vane pumps.
Depending on the arrangement of the gears, a distinction is made between internal and external gear pumps. While internal gear pumps contain two co-rotating gears, external gear pumps contain two counter-rotating gears. Main applications of the gear pumps are agricultural, forestry and construction machinery as well as in stationary industrial applications.
Axial piston pumps
In the case of axial piston pumps, a distinction is made between fixed displacement pumps and variable displacement pumps, the latter being again divided into open and closed circuit. The displacement results from the diameter and stroke of the pistons. Axial piston pumps can be used universally due to their simple controllability of pressure and delivery volume.
Radial piston pumps
In radial piston pumps, in contrast to axial piston pumps, the pistons are arranged radially and perpendicular to the shaft. The stroke or delivery movement is executed by an eccentric or external eccentric lying on the shaft. A stroke ring controls the travel of the piston or the displacement volume. Radial piston pumps are frequently used in industrial high-pressure applications and in injection molding and stamping machines.
Vane pumps are often referred to as rotary vane pumps and consist of a hollow cylinder (stator) in which another cylinder (rotor) rotates. They belong to the group of positive displacement pumps and are therefore divided into 4 process phases (suction, delivery, discharge, pressure change). Centrifugal forces create sealed chambers and thus a suction and a discharge side.