The hydraulic pump supplies the hydraulic motor with pressurized liquid. Without it, it would be impossible to power many machines used in industry, as well as in many specialized vehicles.
The hydraulic pump converts the mechanical energy supplied by the propulsion engine (internal combustion, electric) to the hydraulic energy. The energy contained in the working medium pumped to the installation under the right pressure and with the appropriate efficiency. This can be done in many ways. Hence the multitude of types of hydraulic pumps – vane, gear, screw and piston. Gear pumps are divided into single-section and multi-section, while piston pumps are divided into single-stream and double-stream. However, regardless of the type, each pump has the same task.
The piston pump consists of several small piston pumps placed in one body. Multi-piston pumps are divided into radial and axial. In both cases, the principle of operation is the same. The pump pistons located in the body rest on an inclined disk or on an eccentric ring in a radial pump. Rotary movement of the ring or disc forces reciprocating movement of the pistons. Therefore, the pleasure is sucked and pressed. Multi-piston pumps are not equipped with valves. Their role is played by the distribution disc in the axial pump or the distribution shaft in the radial pump. They rotate with the ring or disc connecting the working spaces of the cylinders alternately to the suction or discharge line.
Gear pumps are constant capacity pumps. They are characterized by simple construction and high reliability. The pressure range is from 3.5 to 28 MPa and geometric capacities from 0.6 to 400 cm³ / rev. The pump capacity depends on the geometrical capacity and engine speed. Gear pumps efficiency depends on the temperature of the liquid. It is because as the temperature increases, the viscosity of the liquid decreases. There are two types of gear pumps, external gearing and internal gearing.
Rotary Vane Pumps
The rotary vane pumps due to their delicate design are used only for pumping gases and clean and self-lubricating liquids. A key design element of vane pumps is the rotor. During the movement of the rotor, the vanes move the working medium from the suction chamber to the inter-vane space. Traditionally, they are used in hydraulic drives of machine tools. The pressure achieved in these pumps is up to 6 MPa with a capacity of 3 dm³ / s and a speed of up to 3000 rpm. Depending on the design, they can work as vacuum pumps, air compressors or liquid pumps.
The design of screw pumps is based on a worm screw, which through rotation rotates the working medium. Liquid enclosed in the spaces between the screw and the pump body is transferred from the suction side to the pressure pump. The screw pump, like a multi-piston pump, has no valves. Screw pumps capacity is up to 0.2 m3 / s, the pressure achieved at a speed of up to 18,000 rpm – 20 MPa. Screw pumps are slightly less efficient than gear pumps.