A directional control valve is used in hydraulic systems to precisely control the flow of hydraulic fluid. The valves allow directional control of the fluid by diverting the flow in different directions.

Detour from a source to an actuator or from an actuator to the return line are possible. This allows hydraulic cylinders or hydraulic motors to be controlled to perform movements in different directions.

In this article, we take a closer look at the functions, features and designs of directional control valves. Be sure to read on and learn more about ARGO-HYTOS solutions for hydraulics.

How do directional control valves actually work?

Directional control valves provide precise control of flow in hydraulic lines. They provide several functions that are critical to the efficient operation of a hydraulic system.

The first function of a directional control valve is to control the direction of flow. It can divert flow from a source to an actuator or from an actuator to the return line. This allows movement in different directions, such as forward and reverse movement of a hydraulic cylinder or rotation of a hydraulic motor.

Another important function of the directional control valve is to block the flow. In certain situations, it is necessary to stop the flow. This applies, for example, when a certain function is not needed or when maintenance work is being performed on a part of the system.

The directional control valve can block the flow and prevent the hydraulic fluid from entering a certain area. This allows maintenance work to be carried out without paralyzing the entire system.

What are the characteristics of directional control valves?

A characteristic feature of directional control valves is the number of connections and switching positions. Depending on the application and requirements, directional control valves with different connections and switching positions can be selected.

The number of connections indicates how many hydraulic lines can be connected to the valve. The number of switching positions indicates how many different positions the valve can take to control the flow accordingly.

By combining different connections and switching positions, directional control valves can be used in a variety of ways and allow for complex hydraulic control systems.

Another aspect is the different spool shapes of directional control valves and their functions. ARGO-HYTOS offers a variety of spool shapes for directional control valves, including:

• 4/3 directional control valve with Y spool for unpressurized float position
• Hydraulically releasable check valves
• Overcenter valves

Each spool shape has its specific function and is suitable for certain applications. Choosing the right spool shape enables optimal control of the hydraulic system and ensures reliable and precise operation.

Directional control valves with different characteristics from ARGO-HYTOS

Directional control valves are available from ARGO-HYTOS in a wide range of designs and variants. The range includes over 30 different spool shapes as standard, which are suitable for different applications and functions. In addition, we always offer our customers the option of having special spools developed and manufactured by our experts.

When selecting a directional control valve, various options are available to customize the function and actuation of the valve. We have developed ten different manual overrides to allow manual control of the valve in an emergency.

Furthermore, seven different nominal voltages of the solenoids at the coil connection are available for selection. They ensure optimum adaptation to electrical systems. Five different solenoid coils are also available for electromagnetic actuation.

The plug variants also play an important role in the installation and connection of the directional control valves. We offer nine different plug variants to enable easy and safe connection with other components of the hydraulic system.

We place great emphasis on the quality and durability of our products. Therefore, directional control valves from ARGO-HYTOS are subjected to a salt spray test according to DIN EN ISO 9227. This ensures reliable surface protection for up to 1,000 hours.

Types of directional control valves

A common design of directional control valves are the screw-in cartridge valves. These valves are characterized by their simple assembly, as they can be screwed directly into the corresponding threaded connections. The screw-in cartridge valves allow a flexible design of the hydraulic system and can be easily adapted and extended.

Spool type design with housing

Another design of directional control valves is the spool design with housing, also known as a surface mounted valve with uniform hole patterns according to ISO 440. In this design, a spool made of hardened steel is used as a control element.

The spool is slid as a whole in the cast iron body. It can connect or close ports to change the function of the valve. The spool design allows precise control of flow. It is often used in applications where extremely precise control is required.

Modular design: Directional control valves RPEK

The modular design with directional control valves is also known as RPEK valve design. In this design, the spool is integrated into the module plates for horizontal interlinking. The valve consists of an inlet section with pressure relief valve and/or switchable pressureless circulation as well as one to eight flangeable directional control valves. The P (pressure) and T (tank) connections are looped through all sections.

The modular design offers the advantage of small dimensions, flexibility and compactness. It is particularly suitable for applications where limited installation space is available. By integrating several valves into one module, efficient and reliable control of the flow is made possible.

More designs

Another type of directional control valve is the screw-in cartridge valve in spool design. Here, a spool in a steel sleeve opens or closes radial bores. Also widely used are screw-in cartridge valves with a poppet seat, in which the spool is replaced by a hardened poppet. These designs each offer specific advantages such as simple assembly or technical leakage-free operation.

Significance of the operation and control of directional control valves

Depending on the requirements and application areas, various actuation and control options of directional control valves are available.

Actuation options for directional control valves

• Electromagnetic: Directional control valves can be operated electromagnetically. Here, the force is generated by an actuating element such as a pole tube, coil, armature or plunger. This method of actuation provides precise and reliable control of the valve.
• Manual: Manual actuation methods such as hand force or foot force are used in certain applications. They provide simple and direct control over the directional control valve.
• Mechanical: In mechanical actuation, the directional control valve is controlled by mechanical forces, for example, levers or push buttons.
• Pneumatic: Directional valves can be pneumatically actuated, using compressed air to control flow. This allows for quick and efficient control of the valve.
• Hydraulic: Hydraulic actuation uses hydraulic control pressure to move the spool of the directional control valve. This method provides precise and reliable control of the valve.

Meaning of spring return or pulse control with detent

Spring return or pulse control with detent is an important function in the actuation of directional control valves. It allows the valve to return to a specific position when the actuating force is removed. This ensures defined control of the flow and safe operation of the valve.

The detent ensures that the valve remains in the desired position even when no actuating force is applied. This is particularly important in applications where the position of the valve must remain stable over a long period of time to ensure reliable operation of the system.

Conclusion: The importance of directional control valves

Directional control valves enable precise control of flow in hydraulic systems. The valves provide directional control or block flow for specific functions or maintenance. They can be optimally used to ensure efficient operation and reliable control.

Would you like to learn more about our product portfolio? Or are you interested in an individual solution for your application? Then do not hesitate to contact the experts at ARGO-HYTOS. We offer comprehensive advice and support in selecting and implementing the most suitable valve technology for your needs.

Visit our contact page and let us advise you personally and without obligation!