Abstract: A hydraulic bolt tensioning device has a cylinder supported on a machine part that is to be clamped by threaded bolt and nut. An exchangeable bushing has a first end screwed onto a free threaded end of the threaded bolt that projects past the nut. A tensioning piston is seal-tightly guided in the cylinder and supported on a second end of the exchangeable bushing. A pressure medium is supplied into an annular space between cylinder and piston. A control device is provided for setting a nominal pressure of the pressure medium corresponding to a nominal pretension of the threaded bolt. A yield limit detection device detects whether a yield limit of the threaded bolt is reached during tensioning. A controller acts on a pressure relief device for pressure relief of the bolt tensioning device when reaching, or shortly after reaching, the yield limit of the threaded bolt.

Abstract: A nut for screw connections has two substantially identically sized nut segments of a half-shell shape, wherein the nut segments each have an inner side provided with an inner thread segment defining together an inner thread. The nut segments are connected to each other so as to be moveable toward each other until the nut segments reach a closed position. The nut segments are maintained in the closed position by springs or a locking device. An actuating device is moveably arranged on at least one of the two nut segments for releasing the closed position, wherein the actuating device is adapted to manually actuated.

Abstract: In a method for controlling a hydraulic power wrench with a pivotable lever pivoted by a piston-cylinder unit and a ratchet arrangement for stepwise rotation of a ratchet bushing by advancing and return strokes, parameters such as nominal torque or pre-load or screw parameters are entered into an electronic input unit. Nominal pressure corresponding to the parameters is determined by an electronic evaluation unit and generated by the pump. The piston-cylinder unit is pressure-loaded for performing a pre-stroke until the nominal pressure is reached followed immediately by a return stroke. A time interval from beginning of pressure loading until reaching nominal pressure or until reaching an initial pressure after pressure relief is measured. Pressure loading and measuring are repeated. The measured time intervals are compared. Pressure loading cycles are stopped when at least the last measured time interval is shorter than at least the penultimate measured time interval.

Abstract: A nut for screw connections has two substantially identically sized nut segments of a half-shell shape, wherein the nut segments each have an inner side provided with an inner thread segment defining together an inner thread. The nut segments are connected to each other so as to be moveable toward each other until the nut segments reach a closed position. The nut segments are maintained in the closed position by springs or a locking device. An actuating device is moveably arranged on at least one of the two nut segments for releasing the closed position, wherein the actuating device is adapted to manually actuated.

Abstract: A screwed connection has a threaded bolt; a nut; a washer arranged between the nut and a surface of a component to be clamped; a screwing device with a housing, a holding tool connected to the housing, and a tightening tool that engages positively the nut; a measuring element arranged in the washer for measuring a compressive force generated by tightening the screwed connection. The washer has an anti-rotation device oriented toward the surface of the component. The outer periphery of the washer is positive-lockingly engaged by the holding tool. The washer has no positive or frictional connection to the threaded bolt, and the holding tool has no torque supporting action on the threaded bolt or on any other part so that a reaction moment, generated when tightening the nut, is introduced from the housing of the screwing device through the washer into the component to be clamped.

Abstract: This invention relates to a method for hydraulically tensioning screw bolts as well as to screw bolts and screw bolt tensioning devices for carrying out the method. It is proposed to apply the total pretensioning force for one part via an external thread and for the remaining part via an internal thread of the bolt end.

Abstract: A hydraulic bolt tensioning device has a cylinder supported on a machine part that is to be clamped by threaded bolt and nut. An exchangeable bushing has a first end screwed onto a free threaded end of the threaded bolt that projects past the nut. A tensioning piston is seal-tightly guided in the cylinder and supported on a second end of the exchangeable bushing. A pressure medium is supplied into an annular space between cylinder and piston. A control device is provided for setting a nominal pressure of the pressure medium corresponding to a nominal pretension of the threaded bolt. A yield limit detection device detects whether a yield limit of the threaded bolt is reached during tensioning. A controller acts on a pressure relief device for pressure relief of the bolt tensioning device when reaching, or shortly after reaching, the yield limit of the threaded bolt.

Abstract: A safety device on a high-pressure connector of a hydraulic device has a shield that surrounds the high-pressure connector and catches hydraulic liquid that escapes at high pressure. The shield has a housing surrounding seal-tightly a pressure medium distributor on the hydraulic device and has furthermore a protective pipe connected to the housing and surrounding a connecting nipple for a high-pressure hose conduit adapted to be coupled by a hose coupling.

Abstract: The invention relates to a switching device for a hydraulic high-pressure system, particularly for operating hydraulic screw-tightening devices, comprising: a directional seat valve (17), which is subjected to the action of high pressure in the closing direction; a control piston (22), which can be subjected to the action of low pressure and which displaces the directional seat valve in the opening direction, and, a control valve (23), which either establishes or interrupts a connection to a pressureless low-pressure return flow line.

Abstract: A hydraulic screw tensioning device includes a cylinder supported on a machine part that is to be clamped by a threaded bolt and nut. A first annular piston is guided in a sealed manner in a cylinder element, is disposed on the change sleeve, and is supported against an inclined surface of a monolithic collar of the change sleeve. At least one second annular piston is guided in a sealed manner in a cylinder element, is disposed on the change sleeve, and is supported against the first annular piston. Respective, facing inclined axial annular surfaces on the annular pistons and on the cylinder elements or annular shoulders thereof are inclined in the same direction and are pressure-remote. Annular surfaces on the second annular piston or pistons and on the annular shoulders of the cylinder elements extend perpendicular to the cylinder axis and are pressurized.

Abstract: In a method for controlling a hydraulic power wrench with a pivotable lever pivoted by a piston-cylinder unit and a ratchet arrangement for stepwise rotation of a ratchet bushing by advancing and return strokes, parameters such as nominal torque or pre-load or screw parameters are entered into an electronic input unit. Nominal pressure corresponding to the parameters is determined by an electronic evaluation unit and generated by the pump. The piston-cylinder unit is pressure-loaded for performing a pre-stroke until the nominal pressure is reached followed immediately by a return stroke. A time interval from beginning of pressure loading until reaching nominal pressure or until reaching an initial pressure after pressure relief is measured. Pressure loading and measuring are repeated. The measured time intervals are compared. Pressure loading cycles are stopped when at least the last measured time interval is shorter than at least the penultimate measured time interval.

Abstract: A nut for a screw connections has, in the circumferential direction, segments that are substantially of the same size, abut one another in separating planes, and are movably guided relative to one another between an open position and a closed position. Closing elements serve for movement of the segments toward one another into the closed position. In order to provide a segmented nut that is suitable for many applications in facility and apparatus engineering, the segments are pivotable relative to one another and connected for this purpose in a first end area in a pivotable way. The closing elements load the segments in the second end areas.

Abstract: A hydraulic screw tensioning device for adjusting screws or bolts includes a cylinder supported on a machine part to be clamped by a threaded bolt and nut, at least one piston guided in the cylinder, a change sleeve threaded onto a threaded end of the bolt, a rotary sleeve in the cylinder for positive connection with the nut, first and second gear mechanisms for driving connection with the rotary sleeve and the change sleeve, respectively, a drive motor for the gear mechanisms, a connecting shaft between gears in the second gear mechanism and first gear mechanism, a device for alternative coupling of the drive motor with the change sleeve or the rotary sleeve, and respective recesses or extensions on a gear secured to the change sleeve and on the gear in the second gear mechanism to positively receive a tool for driving the connecting shaft.

Abstract: A hydraulic threaded bolt clamping device for tightening and releasing threaded bolts has a pressure medium supply connected to a pressure medium connector. A cylinder rests against a machine part that is to be clamped and a periodically pressure-loaded piston is guided seal-tightly in the cylinder and rests against a threaded bushing screwed onto the threaded bolt. A control device actuates the pressure medium supply for supplying pressure medium to the bolt clamping device. After a nominal value corresponding to a nominal prestressing force has been reached the pressure medium supply is switched off. The nominal screw prestressing force or a corresponding nominal pressure of the pressure medium supply is preset by an input device. A measuring device measures relative displacement of the threaded end of the bolt relative to the cylinder. An evaluation device determines residual actual screw prestress after pressure relief of the bolt clamping device.

Abstract: A screwed connection has a threaded bolt; a nut; a washer arranged between the nut and a surface of a component to be clamped; a screwing device with a housing, a holding tool connected to the housing, and a tightening tool that engages positively the nut; a measuring element arranged in the washer for measuring a compressive force generated by tightening the screwed connection. The washer has an anti-rotation device oriented toward the surface of the component. The outer periphery of the washer is positive-lockingly engaged by the holding tool. The washer has no positive or frictional connection to the threaded bolt, and the holding tool has no torque supporting action on the threaded bolt or on any other part so that a reaction moment, generated when tightening the nut, is introduced from the housing of the screwing device through the washer into the component to be clamped.

Abstract: A hydraulic threaded bolt clamping device for tightening and releasing threaded bolts has a pressure medium supply connected to a pressure medium connector. A cylinder rests against a machine part that is to be clamped and a periodically pressure-loaded piston is guided seal-tightly in the cylinder and rests against a threaded bushing screwed onto the threaded bolt. A control device actuates the pressure medium supply for supplying pressure medium to the bolt clamping device. After a nominal value corresponding to a nominal prestressing force has been reached the pressure medium supply is switched off. The nominal screw prestressing force or a corresponding nominal pressure of the pressure medium supply is preset by an input device. A measuring device measures relative displacement of the threaded end of the bolt relative to the cylinder. An evaluation device determines residual actual screw prestress after pressure relief of the bolt clamping device.

Abstract: A double nut for a controlled fixing of a component using a bolt connection, comprising a pulling sleeve having an internal thread adapted to be screwed onto a threaded end of a bolt, and a pressing sleeve adapted to be supported on the component. An internal thread of the pressing sleeve is adapted to be screwed onto an external thread of the pulling sleeve, and engages such external thread to such an extent that the internal thread of the pressing sleeve is spaced by a distance equaling several threads from that end of the pulling sleeve that faces the component. The external thread of the pulling sleeve is furthermore adapted to threadedly receive a pull bushing of a bolt-tightening cylinder that has a support bushing adapted to be supported on the component and to extend over the pulling sleeve and the pressing sleeve.

Abstract: A hydraulic screw tensioning device for tightening and loosening highly stressed screws or bolts comprising a cylinder supported on a machine part that is to be clamped by a threaded bolt and nut. A change sleeve is threaded onto a threaded end of the bolt. A first annular piston is guided in a sealed manner in a cylinder element, is disposed on the change sleeve, and is supported against an inclined surface of a monolithic collar of the change sleeve. At least one second annular piston is guided in a sealed manner in a cylinder element, is disposed on the change sleeve, and is supported against the first annular piston. Respective, facing inclined axial annular surfaces on the annular pistons and on the cylinder elements or annular shoulders thereof are inclined in the same direction and are pressure-remote. Annular surfaces on the second annular piston or pistons and on the annular shoulders of the cylinder elements extend perpendicular to the cylinder axis and are pressurized.

Abstract: A hydraulic screw tensioning device for tightening and loosening highly stressed screws or bolts comprising a cylinder supported on a machine part to be clamped by a threaded bolt and nut at least one piston guided in the cylinder and periodically supplied with pressure, a change sleeve to be threaded onto a threaded end of the bolt, with the piston resting against the change sleeve, a rotary sleeve in the cylinder for positive connection with the nut, a first gear mechanism for driving connection with the rotary sleeve, a second gear mechanism for driving connection with the change sleeve, a drive motor for the gear mechanisms, a connecting shaft between a gear in the second gear mechanism and a gear in the first gear mechanism, a device for alternative coupling of the drive motor with the change sleeve or the rotary sleeve, and respective hexagonal or square recesses or extensions on a gear secured to the change sleeve and on the gear in the second gear mechanism to positively receive a tool for driving the