Hydac Fluidtechnik Gmbh

Gerd Anton Thiry

Alois Hoffmann

Harald Bär

Martin Schaus

Harald B&auml;r

A circuit arrangement includes a load sensing system (LS) with individual loads () arranged in series forming a series section, and in parallel forming a parallel section. A hydraulic supply circuit () includes a supply pump (P) and a runback () for fluid. The load sensing system (LS) determines the highest load pressure in the series section and the parallel section. The loads of the parallel section can be actuated independently from the pressure level of the loads of the series section due to the highest load pressure being transferred as a control pressure to a valve unit () such that, as long as the load pressure of the parallel section is higher than the load pressure of the series section, the valve unit restricts the runback () so that the pressure of the supply pump (P) matches or exceeds the pressure required in the parallel section. Sufficient fluid pressure for the load in the parallel section is ensured independently of the number of loads in the series section.

Circuit arrangement

A switching device for a machine, especially a digger, has at least one supply connection and one useful connection in addition to at least one hydraulic accumulator. An on-off valve is arranged between the supply connection and the useful connection, and separates the supply connection at least partially from the useful connection in one of its switching positions, in addition to ensuring that the hydraulic accumulator is charged on the fluid side via the supply connection. In another switching position, the supply connection is connected to the useful connection. A substantial improvement relative to conventional switching devices is attained by being able to guarantee an emergency function before the machine is used to perform work.

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Wadgassen, Germany

Gerd Anton Thiry