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The variable displacement pump

If you're looking for a pumping solution for your industrial applications, you may have heard of the automatic hydraulic pumps variable displacement pumps. This is because these pumps are designed with advanced technology that allows the amount of liquid pumped to be adjusted at each revolution, unlike fixed-displacement pumps. In this article, we will explore in detail the advantages and features of automatic variable displacement hydraulic pumps, as well as their operation and use in various industrial applications.

How does a variable displacement pump work ?

Cours 33 - Pompe à cylindrée variable avec régulation de puissance

Variable displacement hydraulic pumps work by adjusting the amount of hydraulic fluid pumped with each revolution of the pump shaft. Unlike fixed displacement pumps, which always pump the same amount of liquid, variable displacement pumps can adjust the amount of liquid pumped according to the needs of the application.

This is because the operation of the variable displacement pump is controlled by a displacement control system that can increase or decrease the amount of liquid pumped by adjusting the size of the pumping chamber. This is usually achieved via a pressure regulation system, which measures the hydraulic pressure in the system and adjusts the pump displacement accordingly.

In addition, these types of pumps are equipped with flow sensors to measure the flow of liquid being pumped at any given time, enabling displacement control systems to adjust the amount of liquid being pumped in real time to maintain the desired pressure.

What types of variable displacement pump are there ?

The variable displacement pump is available as an axial piston pump, a radial piston pump and a vane pump.

Each type of variable displacement pump offers unique performance benefits. So it's important to choose the right type of pump for your specific application.

Variable displacement axial piston pump

Cylindrée variable pompes à pistons axiaux pour circuits ouverts | Bondioli  & Pavesi

La variable displacement axial piston pump uses pistons that slide along the pump shaft to suck in and discharge hydraulic fluid. The pump's displacement is adjusted by modifying the angle dthis allows the amount of liquid pumped to be adjusted with each revolution.

Variable displacement axial piston pumps are used in industrial applications requiring high flow rates and precise regulation, such as hydraulic presses, plastic injection moulding machines or paper production machines.

Pump With variable displacement radial pistons

Pompe hydraulique à pistons radiaux - R - HAWE Hydraulik SE - compacte /  modulaire

La variable displacement radial piston pump uses a rotor that rotates in a circular pump chamber, driving pistons that slide on cylindrical sleeves to suck in and discharge hydraulic fluid. The pump's displacement is adjusted by altering the distance between the rotor and the cylindrical sleeves, so that the amount of fluid pumped at each revolution can be regulated.

Variable displacement radial piston pumps are often used in industrial applications requiring medium flow rates and high pressures, such as drilling machines and construction equipment.

Variable displacement vane pump

Pompes à palettes [Hydraulique : De la mécanique des fluides à la  transmission de Puissance]

In a variable displacement vane pump, the pump axis is eccentric with respect to the pump casing. The vanes are inserted into the slots in the rotor and held against the pump casing by springs. As the rotor rotates, the vanes slide along the housing, creating a suction chamber that draws hydraulic fluid into the pump. The vanes then move towards the centre of the pump, compressing the hydraulic fluid in a pressure chamber and pumping it to the hydraulic system.

These types of pumps are often used in industrial applications requiring low to medium flow rates and moderate pressures, such as machine tools and lifting equipment.

Why use a variable displacement pump ?

Variable displacement pumps offer many advantages over fixed displacement pumps. These include:

- Precision

Variable displacement pumps can provide a precise and constant flow rate, even in the presence of fluctuations in system pressure. This is made possible by their ability to adjust the amount of fluid pumped at each revolution.

- Energy efficiency

Variable displacement pumps are more energy efficient than fixed displacement pumps because they can adapt to the needs of the system and pump only the amount of fluid required. This reduces energy consumption and the associated costs.

- Flexibility

These types of pump offer greater flexibility than fixed-displacement pumps. They can be used in a wide variety of industrial applications, as they can be adapted to the specific needs of each system.

What's more, they can be combined with other hydraulic equipment to provide complete solutions for industrial applications.

- Durability

Variable displacement pumps last longer because they are able to adapt to fluctuations in pressure and flow.

They also do not operate at full capacity all the time, which reduces wear and tear on components.

How can a variable displacement pump be used ?

Variable displacement hydraulic pumps are used in a wide variety of industrial applications.

In the manufacturing industry, they are used for machine tools, presses, industrial robots, welding equipment, plastic injection machines and other industrial production equipment.

In the construction industry, variable displacement pumps are used in equipment such as excavators, bulldozers, graders, loaders, compactors and cranes.

In the energy sector, variable displacement pumps are used in power stations, wind turbines, hydraulic turbines and oil drilling equipment.

These types of pumps can also be used in agricultural equipment such as tractors, combine harvesters, sprayers and spreaders.

How do I maintain a variable displacement pump ?

Pompe à débit variable, pompe à piston

Whether it's a piston or vane pump with variable displacement, maintenance is crucial to ensure optimum performance and long life. To do this, you need to :

- Regularly check the condition of pump components such as seals, valves, hoses and connections for signs of wear, leakage or damage ;

- Lubricate the pump regularly with the lubricant recommended by the manufacturer ;

- Replace worn parts immediately with others of equivalent or even higher quality ;

- Clean the pump regularly with solvents and cleaners compatible with the pump components.

Still on the same theme

Fixed displacement pump