Classification of hydraulic pumps
In construction machinery of various manufacturers, we can find different types of hydraulic pumps, which are used to operate individual systems. There are several such components in a single machine. What are the differences between them?
Fixed displacement pumps
These are usually gear pumps or vane pumps. They are characterized by a simple construction and uncomplicated operation. They are most often used in working and control systems, so they can be used in practically any construction machine.
Fixed displacement pumps do not have to drive the basic functions of machines - they can also be used to drive additional equipment functions, such as: rotators of grips/clamps, drilling heads, hydraulic saws, sifters, etc.
A special feature of this type of pump is that in control systems they work at lower pressure - then low-performance gear pumps are used.
Fixed displacement pumps can also be used to drive cooling system fans, drive system brake operation and rotation reducer as well as gearbox control. Their application is very wide, which is why they are still very popular.
Variable displacement pumps
Among them, we will find mainly piston pumps, which are characterized by a much more complicated construction than gear or vane pumps. They are used in working systems and travel drives of construction machines.
The main advantage of variable displacement pumps is a very wide range of performance changes, which allows them to work at high pressure.
It is possible to easily adjust and control the stream of hydraulic oil produced by the pump, which in turn translates into excellent performance parameters of the component and reducing the costs of operating the machine.
Manufacturers independently establish main pump control systems and combustion engines to achieve the highest performance and work ergonomics.
Thanks to this, the pump adjusts its performance depending on the system's demand - the engine is not so loaded, its lifespan is extended, fuel consumption decreases. All this has made piston pumps currently the most common in the role of main pumps in mobile hydraulics systems.
Piston pumps also come in versions with fixed displacement - such components are used to operate specific functions in the machine, e.g. fan drive or rotation motor drive.
Classification of variable displacement pumps
These pumps are divided into two subgroups:
- Closed circuit pumps
- Open circuit pumps
Pumps from the first group are used in drive systems - they handle the driving function of loaders, dozers, spreaders, drills, crushers or excavators. In excavators, these pumps are also used to drive machine rotation.
Pumps working in open systems most often serve to move machine actuators and, depending on the machine's design, can drive hydraulic drive motors, hydraulic hammers or sifters.
