| 摘要 |
A hydraulic actuation arrangement including a double-action working cylinder whose working chambers are in communication via a mutually unseatable check valve with one side of a reversible pressure medium source, respectively, whereby each working chamber is connected to a pressure medium reservoir by a pressure-relief valve or pressurizing valve, and at least one working chamber is furthermore connected to the pressure medium reservoir via an additional pressurizing valve. When an additional pressurizing valve is provided with two different pressure threshold values, the manual force used in emergency operation is therefore clearly reduced after introduction of the manual movement whereby these force levels for both movement directions may be selected independently from the maximum system pressure. A two-stage pressurizing valve includes a flow-through opening in the passage that may be blocked by the valve element whereby the surface of the flow-through opening is smaller than the cross section surface of the valve element.
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