What Is Load Sensing?

Load Sensing (LS) is a hydraulic pressure and flow control system that automatically adapts the power supplied by the pump according to the load required by the actuators (hydraulic cylinders or hydraulic motors).

Instead of operating at constant flow and pressure like conventional hydraulic systems, Load Sensing “detects” demand and responds in real time based on those requirements.

How Does It Work?

The operating principle of a Load Sensing system is simple:

• The control valves send a pressure signal (LS signal) to the pump.

• That signal represents the highest load currently operating in the system.

• The variable displacement pump adjusts its displacement to maintain a pressure slightly higher than required.

• When there is no demand, the pump reduces its flow almost to zero.

This prevents the generation of unnecessary hydraulic energy.

What Are the Main Components of a Load Sensing System?

A Load Sensing hydraulic system is made up of several elements working together to regulate pressure and flow according to actual demand.

• Variable displacement pump. It is the heart of the system. Typically an axial piston pump with variable displacement. It automatically adjusts its output to deliver only the required flow.

• Pump regulator (LS control). This mechanism receives the load signal and modifies the swash plate angle of the pump. It maintains a constant pressure differential between working pressure and the LS signal.

• Load Sensing signal line (LS line). A small-diameter hydraulic line that transmits load pressure from the control valve to the pump regulator. It always sends the highest working pressure in the system.

• Pressure-compensated control valves. Special valves that regulate flow to each actuator, incorporate pressure compensators, and allow simultaneous operation of multiple functions without one “stealing” flow from another.

• Pressure compensator valves. They maintain a constant pressure drop across each valve section, ensuring proportional and smooth movements.

• Hydraulic actuators. The working elements of the system (hydraulic cylinders and hydraulic motors).

• Pressure relief valve. Protects the system from overpressure.

• Optional components. Modern systems may include electronic pressure sensors, electrohydraulic control, CAN-Bus modules, and function prioritization systems.

In next-generation tractors and harvesters, Load Sensing systems are often integrated with Closed Center Load Sensing (CCLS) hydraulic systems, electronic implement control, and proportional joysticks. This enables precision, energy efficiency, and simultaneous multi-function operation.

What Equipment Uses Load Sensing?

Load Sensing systems are mainly used in:

• Agricultural machinery

• Road construction equipment

• Hydraulic cranes

• Forestry equipment

• Aerial work platforms

In general, they are used in machines where multiple hydraulic functions operate simultaneously.

What Advantages Does It Offer?

Compared to open center or conventional closed center systems, Load Sensing optimizes engine power usage.

• Greater energy efficiency

• Lower fuel consumption

• Reduced heat generation

• Improved movement precision

• Ability to operate multiple functions simultaneously

• Reduced component wear

What Is Its Application in Agricultural Machinery?

In agricultural machinery, Load Sensing is key because it allows:

• Precise control of seeders and fertilizer spreaders

• Improved response in sprayers

• Simultaneous operation of multiple cylinders in harvesters

• Greater efficiency in high-horsepower tractors

• Better compatibility with modern implements requiring variable hydraulic demand

Conclusion

Load Sensing automatically adjusts hydraulic output, making the system smarter and more efficient.

Conventional hydraulic systems, by contrast, typically operate at fixed flow, wasting energy when it is not needed.