US Patent 7320272 Hydraulic system

The present application relates to a hydraulic system having a hydraulic supply, a consumer and having a control valve, which is in communication with the consumer by means of a first line and a second line, it being possible for the control valve to be switched into different positions, and the control valve connecting the hydraulic supply to the first line in at least one position. Furthermore, a first valve, which is in communication with the first line and the second line, is provided. Moreover, a third line, serving as a further return, which is in communication with the first valve and does not lead to or open out in the control valve, is also provided, the first valve being connected in such a manner that when pressure is applied to the first line it opens up a connection between the second and third lines.