Patent ID: 9334884
Filing Date: 2016-05-10
CPC Classification: F15B

Claim Text:
1. A hydrostatic drive system, comprising: a user comprising a differential cylinder connected in a closed circuit to a high-pressure pump, in which a piston-side compression chamber of the differential cylinder is in communication with the high-pressure pump by a first power fluid line, and a piston-rod-side compression chamber of the differential cylinder is in communication with the high-pressure pump by a second power fluid line, wherein the closed circuit comprises a protection device comprising a first protection valve device that comprises a pressure relief valve and an anti-cavitation valve which is associated with the first power fluid line, and a second protection valve device which comprises a pressure relief valve and an anti-cavitation valve which is associated with the second power fluid line, wherein the protection valve devices are connected with a low-pressure system, and wherein the pressure relief valve of the first protection valve device associated with the first power fluid line includes an override device by means of which an opening pressure of the pressure relief valve is varied between a protection pressure of the closed circuit and a reduced opening pressure, whereby when the high-pressure pump delivers into the piston-rod-side compression chamber, the pressure relief valve of the first protection valve device is adjusted by the override device to the reduced opening pressure due to an actuation of a control element controlling an actuation of the user, and a differential volumetric flow flows out via the pressure relief valve from the first power fluid line into the low-pressure system, and the pressure relief valves of the first protection valve device and the second protection valve device have a protecting pressure that protects a high pressure of the closed circuit, wherein the low-pressure system has a low-pressure pump that is operated in the open circuit and delivers into a delivery line, and a pressure protection device is associated with the delivery line, wherein the pressure protection device of the low-pressure system is a pressure relief valve, the protection pressure of which is varied by an adjustment device, wherein the override device of the pressure relief valve and the adjustment device of the pressure protection valve are actuated as a function of the actuation of the control element.