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.
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.
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