Patent ID: 8037681

Claim:
A hydrostatic drive system, comprising: a load-sensing pump having an adjustable discharge volume; at least one consumer connected to the pump; a discharge volume control device, wherein a discharge volume of the pump is set by the discharge volume control device which sets a delivery pressure of the pump available in a delivery line of the pump so that the delivery pressure of the pump is higher by a pilot control pressure difference than a load pressure of the consumer; an electronic control device that actuates the discharge volume control device of the pump, the electronic control device being functionally connected with a sensor device for measuring the load pressure of the consumer and with a sensor device for measuring the delivery pressure available in the delivery line of the pump; and a circulation device associated with the delivery line of the pump to control a connection of the delivery line of the pump with a reservoir, the circulation device including a spring, wherein a pressure in the delivery line is equal to or less than a sum of the load pressure of the consumer plus a target pilot control pressure difference of the hydrostatic drive system to achieve a load-independent operation of the consumer in the hydrostatic drive system, wherein the circulation device performs a load-sensing control and accurately controls the pressure in the delivery line so that the pressure in the delivery line is equal to or less than the sum of the load pressure of the consumer plus the target pilot control pressure difference of the hydrostatic drive system and wherein the circulation device is actuated by the spring toward a closed position, a bias of the spring being equal to the target pilot control pressure difference of the hydrostatic drive system, and wherein the electronic control device actuates the discharge volume control device with a low degree of control accuracy for all load pressures.