Load Sensing (LS)
Load sensing is the circuit logic based on the valve reporting the pressure of the currently heaviest working section to the pump through a thin signal line, with the pump adjusting its flow to that demand. The difference between pump outlet and load pressure is typically held constant at 15-25 bar. Standby loss is almost zero.
The system works in three parts: pressure-compensated working sections, the LS signal line, and the pump's LS regulator. The highest load pressure is selected through a chain of shuttle valves and sent to the pump. The pump operates by adding the fixed differential to this value; as much as the lever is opened, that much flow is produced.
- Simultaneous motion: thanks to per-section pressure compensators, a light load does not grab all the flow; motions accelerate independently of each other.
- Efficiency: at standby the pump destrokes, and oil heating and fuel consumption drop markedly.
- Sensitivity: air trapped in the LS line or a restriction leads to unstable, jerky motion.
In this architecture the lever opening directly means a flow demand; the relationship between speed and joystick position is more linear and less load dependent than in an open center system. In electronic lever control, having calibration teach the end points correctly lets you take full advantage of this linearity.
Where this term is used: How Are Manual Hydraulic Levers Controlled Remotely? A Comparison of 6 Methods