Patent ID: 8262063

Claim:
A hydraulic rescue tool, having pivot able parts and a hydraulic valve system having a double-action hydraulic cylinder connected thereto for driving the pivotable parts, wherein the hydraulic valve system comprises: a feed of hydraulic pressure medium; a discharge of hydraulic pressure medium; a first pressure conduit connected to a first chamber of the hydraulic cylinder and provided with a first pressure-controlled non-return valve; a second pressure conduit connected to the second chamber of the hydraulic cylinder and provided with a second pressure-controlled non-return valve; a switch for switching between a connection of the first and second pressure conduit to respectively the feed and the discharge and a connection of the first and second pressure conduit to respectively the discharge and feed; wherein first and second pressure-controlled non-return valves block a plunger of the double-action cylinder when hydraulic pressure is lost, wherein the first and second pressure-controlled non-return valves combined with a differential valve element provide an increased speed of an outward plunger stroke of the double-action cylinder in a first position and provides a normal speed thereof in a second position, and wherein the differential valve element comprises a two-position three-way valve; a third non-return valve arranged in a pressure conduit between the switch and the pressure-controlled non-return valve connected to the second chamber, the third non-return valve blocking flow of fluid from the second chamber to the switch; and a fourth non-return valve arranged in a pressure conduit between the feed and the differential valve element, the fourth non-return valve blocking flow of fluid from the feed to the differential valve element.