Load sensing was developed to improve the efficiency of a circuit. It requires a variable displacement pump; thus, it is appropriate to discuss it here.
An example will illustrate the advantage provided by load sensing. An application requires a maximum flow of 20 GPM at a maximum pressure of 2500 psi. To meet this requirement, a pump must be selected that can supply 20 GPM at 2500 psi. Most of the time, however, the application requires less than 20 GPM at less than 2500 psi. The percentage of total operating time the system operates under reduced load, and the way the system responds to this condition, is a key issue. The specific reduced load situation we will consider is the activation of a cylinder. A metered flow rate of 9 GPM at 1300 psi is required. To understand the advantage of load sensing, it is helpful to review
the operation of an open-center and closed-center circuit that meets the functional objective and then consider a closed-center circuit with load sensing.
