Abstract: A circuit for hydrostatically operable devices, especially hydraulic dredges, with at least two working circuits each of which comprises a plurality of hydraulic cylinders and/or hydraulic motors as well as a hydraulic pump while, depending on the requirement, the delivery of the pertaining hydraulic pump is conveyed to each hydraulic cylinder or hydraulic motor and while by means of a plurality of tie lines the deliveries of the remaining hydraulic pumps are selectively conveyed to one of two or more selected hydraulic cylinders or hydraulic motors. The deliveries of the hydraulic pumps flow to the tank after having passed through the control valves associated with the hydraulic cylinders and controlling each of the hydraulic pumps.

Abstract: Rotary connection having a housing which is provided with annular ducts and with feed bores for pressurized oil and non-pressurized oil and having a piston-shaped inner part arranged in the housing, the inner part being formed with bores and with grooves on its periphery, for the passage of high-pressure oil and practically non-pressurized hydraulic oil. By means of a valve piston which can be acted-on at both end surfaces thereof with pressurized oil, lubricating ducts are connected, depending upon the switched position of the valve piston, via a central longitudinal bore provided with transverse bores, with the respective annular duct which at the time is not applied with pressurized oil.

Abstract: A hydraulically controlled and driven dredge, in which the pumps for delivering the driving fluid for the bucket wheel drive are equipped with output controls for controlling the fluid delivery in conformity with the encountered digging resistance and that a control conduit branched off from a pressure conduit leading to a hydraulic motor for driving the bucket wheel is connected to an output limiting valve located in a control circuit which includes an adjusting device connected through conduits to a manually operable control for varying the delivery and the delivery direction of the pump for actuating the hydraulic motor for pivoting the upper structure of the dredge. The fluid delivery of the pumps to the hydraulic motor employed for driving the track laying mechanism being conveyed to the hydraulic motor for driving the bucket wheel when the track laying mechanism is not to be operated.