| 摘要 |
The invention relates to a control block with a plurality of directional control valves in a common housing. The directional control valves serve to control the pressure-medium paths between a plurality of hydraulic cylinders and a pressure-medium source or tank. A combined pressure-relief and after-suction valve is provided on the primary side between the high-pressure passage connected to the pressure-medium source and the relief passage connected to the tank. The pressure relief serves to protect the hydraulic cylinders against excessively high pressures; the after-suction function prevents the pressure in the high-pressure passage from collapsing and the high-pressure passage from being sucked empty if a load hanging on a hydraulic cylinder is lowered. This is because the cylinder space increasing during the lowering of the load is refilled with working medium from the tank via the after-suction valve. Since the combined pressure-relief and after-suction valve is arranged on the primary side in the control block, the pressure-relief and after-suction function for all downstream directional control valves of the control valve is effected by a single combined valve. <IMAGE>
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