A Comprehensive Guide to Different Types of Hydraulic Pumps
Hydraulic pumps are manufactured to meet specific system necessary such as temperature, pressure, and motor type. It is mainly categorized into three:
Hydraulic pumps
Straight, helical or zigzag gears are used in these pumps. Straight spur gears are commonly used and helical or zigzag gears are more expensive and quieter.
In gear pumps, fluid is transferred between meshing gears. One shaft is used to drive one gear and make the other idle. Gear pumps can withstand pressure around 210 bar and will operate at high speed from 3000-6000rpm. External gear pumps, internal gear pumps, screw pumps and ring pumps are the different classifications of gear pumps.
Both industrial and mobile systems use these pumps in various applications such as machine tool lubrication pumps, fluid power transmission units, and engine oil pumps. Here, to close the teeth of the gear pumps, one wheel is attached to the motor, and the other will rotate in the opposite direction. The bearing block will help position the wheels for minimum clearance while the teeth are engaged. A lobe pump is a type of external gear pump that drives both lobes by motors located outside the chamber.
Internal gear pumps
Internal gear pumps are versatile and can handle thicker hydraulic fluids such as asphalt, chocolate and adhesives. They are used in applications such as plastics, machine tools, presses, electric hoists, etc. These pumps can handle higher viscosity and temperature ranges. Internal gear pumps can run dry for short periods and are self-priming, non-pulsating and bidirectional. These gear pumps are reliable, easy to maintain and operate due to the minimum number of moving parts.
screw pumps
These pumps are commonly used in theaters and opera houses due to their low operating noise level. Among gear pumps, screw pumps have a high displacement volume. These pumps have two or three worm gears inside the pump casing. Therefore, they are also called worm gear pumps. Single-screw, twin-screw and triple-screw pumps are the three classifications. These pumps have an axial flow in the direction of the power rotor and the fluid will flow linearly.
Loop bomb
These pumps are commonly used in hydraulic power steering systems as a pressure lubrication system. The annular pump rotor is built directly into the housing of the high-pressure pump like the radial piston pump.
Vane pumps work efficiently with low viscosity liquids such as ammonia, solvents, alcohols, fuel oils, gasoline and coolants. The lack of metal-to-metal contact within these pumps will eliminate the corrosion associated with them. It has such characteristics as low noise, dry core, easy maintenance and good suction properties. Vane pumps provide a steady flow while maintaining a high speed of up to 3000 RPM.
Operating pressure does not exceed 180-210 bar. Some constant pressure pumps or fixed vane pumps can adjust the center of the vane body. Sliding vane pumps (left), vane vanes, vane vanes, and vane vanes are different types of pumps. Among them, external vane pumps can handle large solids and flexible vane pumps can handle small solids but create a good vacuum. For short periods, slip vane pumps can dry out.
In unbalanced vane pumps, all pumping occurs on one side of the rotor and shaft. Unbalanced vane pumps have a circular casing and balanced vane pumps have an oval casing with different pumping areas on either side of the rotor. The balanced vane pump uses a fixed displacement design, while the unbalanced vane pump uses both constant and variable displacement.
Hydraulic piston pumps
This is a rotating unit that produces a flow of liquid using the principle of a reciprocating pump. These types of pumps use a combination of several piston and cylinder assemblies. Piston pumps can maintain a large flow of liquid at a high temperature. Efficiency, reliability and compact size are the hallmarks of hydraulic piston pumps. These pumps control fluid leakage through effective sealing practices. Axial piston pumps and radial piston pumps are two classifications of piston pumps. In axial piston pumps, the rotary motion is converted into axial reciprocating motion. In the case of a radial piston pump, the pistons are arranged radially.
Source: Rexroth hydraulic pump
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