Abstract: The invention relates to a novel screw tensioning device with a screw tensioning cylinder with a high-pressure hydraulic pump for pretensioning screws and loosening extremely secure pretensable screw connections and an accompanying control method. The problem is to create a screw tensioning device that can generate high tensioning forces, that requires less energy, that can be used for all usage locations without problems, that can be easily controlled and that makes precisely controlled pretensioning possible. A high-pressure hydraulic pump 39 is integrated into the interior of the screw tensioning cylinder 38 in accordance with the invention. This high-pressure pump 39 is connected to a sealed hydraulic accumulator 42. A drive unit 40 that can be pneumatically actuated is arranged on or in the screw tensioning cylinder 38. The drive unit 40 can be designed on the constructional basis of a diaphragm cylinder 42 or on the basis of a piston cylinder.

Abstract: The invention relates to a novel screw tensioning device with a screw tensioning cylinder with a high-pressure hydraulic pump for pretensioning screws and loosening extremely secure pretensable screw connections and an accompanying control method. The problem is to create a screw tensioning device that can generate high tensioning forces, that requires less energy, that can be used for all usage locations without problems, that can be easily controlled and that makes precisely controlled pretensioning possible. A high-pressure hydraulic pump 39 is integrated into the interior of the screw tensioning cylinder 38 in accordance with the invention. This high-pressure pump 39 is connected to a sealed hydraulic accumulator 42. A drive unit 40 that can be pneumatically actuated is arranged on or in the screw tensioning cylinder 38. The drive unit 40 can be designed on the constructional basis of a diaphragm cylinder 42 or on the basis of a piston cylinder.