Load Sensing (LS) hydraulic control valves – advanced optimization of high-pressure systems

Hydraulic control valves equipped with Load Sensing (LS) technology represent the pinnacle of achievement in the field of controlling highly advanced mobile and stationary machinery. Unlike classic Open Center control valves, LS units are designed to work in close correlation with variable displacement pumps. The key idea of the system is sending a "load-sense" pressure signal (the highest operating pressure from currently active sections) directly to the pump regulator. Thanks to this, the pump generates exactly the flow and pressure currently necessary for the cylinder or hydraulic motor to perform work, taking into account the required pressure margin (so-called delta P). This architecture eliminates throttling losses, which are inevitable in constant flow systems, leading to a drastic reduction in fuel consumption and a decrease in the operating temperature of the medium.

Technical characteristics and precision engineering

Each LS control valve in our range is the result of rigorous manufacturing processes. Bodies cast from GJS-class ductile iron are processed in CNC centers, ensuring dimensional tolerances at the micron level. This is essential, as the spools in LS control valves play a dual role: they direct the oil flow and work with pressure compensators. These compensators can be placed before the spool (Pre-compensation) or after the spool (Post-compensation), allowing for Load Independent Flow Distribution – LUDV, enabling smooth operation of several actuators simultaneously, even when the supply pressure is close to the maximum.

In LS systems, oil cleanliness plays a key role. Even small solid contaminants can lead to the jamming of the LS signal nozzle or precision compensation valves. Therefore, during system installation, professional filtration is absolutely necessary. We recommend using advanced filtration systems, which maintain the oil cleanliness class at a level consistent with the ISO 4406 standard (18/16/13 recommended). Proper selection of supporting components, such as high-pressure 4SP hydraulic hoses, ensures stable transfer of the pressure signal without pulsations, which is critical for the stability of the pump regulator operation.

Why is it worth investing in an LS system?

• Extreme energy efficiency: The pump works only when and with the performance required by the load. This means fuel savings of 15-30% compared to standard constant flow systems.
• Control precision: Flow independence from the load (LUDV) allows the operator to perform movements smoothly even with large pressure differences between individual sections.
• Extensive diagnostic possibilities: LS systems have dedicated measurement ports, enabling quick control of operating pressure and the LS signal, which significantly facilitates machine service.
• Modularity and scalability: Each section can be configured individually – from spool selection, through compensator setting, to integrated hydraulic locks and anti-cavitation valves.

Operating parameters

Frequently Asked Questions (FAQ)

1. What is the difference between an LS system with a closed signal (Closed Center) and an open signal (Open Center)?
In a closed-signal LS system, the LS line is cut off from the tank in the neutral position, allowing for a faster pump response at start-up. In systems with older pump types, an open signal (so-called "bleed") may be required, providing a constant pressure relief to the tank.

2. What to do when the machine "jerks" while using several sections simultaneously?
This is a typical symptom of incorrect setting of the compensation valves in the LS block. It should be checked whether the delta P pressure difference is set according to the machine documentation and if the LS signal line is not air-locked.

3. What is the significance of the choice of sealing material in LS control valves?
Due to higher operating temperatures in LS systems, we use Viton (FKM) or high-grade NBR seals, which maintain flexibility and chemical resistance across a wide range of temperatures, which is key to avoiding internal oil leaks.