The primary goal while designing a hydraulic system is to use less energy and do more work. A conventional hydraulic system with a fixed-displacement pump provides a constant flow through the system. The maximum system pressure is limited by the settings of a pressure relief valve in the system.
When the load demands less flow than that delivered by the pump or the load-induced pressure is less than the maximum pressure setting, the load utilizes only a partial amount of the power delivered by the pump, or the pump is not in a position to deliver its full capacity. As a result, there is a tremendous amount of heat development in the system.
Even when a variable-displacement pump is employed in the system, the system produces considerable heat.

Load Sensing Hydraulic Systems
Joji Parambath

Concepts of Load Sensing Hydraulic Systems
Joji Parambath
Ideally, the hydraulic system should provide only the flow and the pressure as required by the connected load. A load sensing system is designed to provide only the flow and the pressure as required by the load.
The basic load sensing system typically comprises a variable-displacement load sensing pump, fitted with a special compensator, and a load sensing directional control valve with proportional flow characteristics.
Joji Parambath
Director
Fluidsys Training Centre Pvt Ltd
Bangalore, India