Hydraulic control of a hydraulic system for a hydraulically actuated liftable and lowerable hook of a crane

摘要

Hydraulic control unit (1) of a hydraulic system for a hydraulically actuated liftable and lowerable hook of a crane, wherein the hydraulic system at least one, which is constructed as a hydraulic motor driven machine (15) and at least one, in particular formed as a pump, driving machine, wherein the working machine (15) by means of two, depending on the operating state of the machine (15) serving as a feed or return, connections by means of corresponding working lines (2), directly or indirectly, with at least one of the drive motors is connected, and wherein in the one working line (2) a lowering brake valve (3) is provided, which, via a control line (4) with the other working line (2) is connected in such a way that the lowering brake valve (3) against a restoring force of its blocking position by the in this working line (2) prevailing and via the control line (4) relayed pressure into a through flow position for the lowering of the hook by means of a winch (16), in particular primary winch, is displaceable, characterized in that for an adjustment of the lowering brake valve (3) on the pressure acting on different values of the control line (4) with a switch (5) between the internal and external control is provided and of the control line (4) between the switching (5) and the lowering brake valve (3) a to a tank discharge line (6) branches off back.