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 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 threaded bolt tightening device (1) for tightening and loosening large bolted connections, comprising a cylinder supported on a machine part to be clamped by means of a threaded bolt and a nut (2), at least one piston which is guided thereon in a sealed manner, with a threaded bush screwed on to one end of the threaded bolt and which can be pressurized, a pressure medium supply (4) to the threaded bolt tightening device (1), an adjusting ring (6) arranged in the cylinder and connected to the nut (2) by a form fit, and a rotary drive (7) for the adjusting ring (6) with a drive connection (16) to the adjusting ring (6), a rotation angle sensor (8) on the rotary drive, a control device (9) for driving the pressure medium supply (4) to the threaded bolt tightening device (1) and the rotation of the rotary drive (7), an input device (1), and the rotation of the rotary drive (7), an input device (10) for entering the pitch of the threaded bolt, and a computer device (11) for converting the rotation angl

Abstract: A hydraulic threaded bolt tightening device (1) for tightening and loosening large bolted connections, comprising a cylinder supported on a machine part to be clamped by means of a threaded bolt and a nut (2), at least one piston which is guided thereon in a sealed manner, with a threaded bush screwed on to one end of the threaded bolt and which can be pressurized, a pressure medium supply (4) to the threaded bolt tightening device (1), an adjusting ring.

Abstract: A high pressure conduit connector is provided. An insertion fitting is partially inserted into a high pressure conduit, and a press-in sleeve is provided that extends over the insertion fitting and the conduit for effecting a pressure-tight connection between them. A safety sheath, preferably embodied as a cylindrical coil spring, is secured to the outer side of the press-in sleeve, and to a portion of the insertion fitting that projects out of the high pressure conduit and the press-in sleeve, at least frictionally.

Abstract: A power screwdriver has a drive unit and an input circuit for inputting screw size, material quality, pitch, and clamping length of a screw. An evaluation circuit is provided for determining a nominal prestress force based on input screw size, material quality, and clamping length, for determining a nominal torque based on the nominal prestress force and the pitch, and for determining the screw clamping angle resulting from the nominal prestress force and the pitch. A sensing device for sensing the actual torque is provided, and a further sensing device for sensing the actual screw clamping angle is present. A control and switch-off device controls further rotation of the drive unit when the actual torque coincides with the nominal torque and switches off the drive unit when the actual screw clamping angle coincides with the nominal screw clamping angle.

Abstract: A measuring device for measuring the extension of a threaded bolt or a screw tightened by a nut has an extension measuring scale provided at a circumference of either the nut, of a screw head of the screw, or of a tightening element rotatable relative to the nut or the screw head of the screw. Reference marks for the measuring scale are arranged stationary relative to the extension measuring scale.

Abstract: A hydraulic tensioning device for a threaded bolt has a cylinder resting on a machine part to be clamped with a threaded bolt and a nut. It further has a threaded bushing threaded onto a free end of the threaded bolt. A piston is guided sealingly in the cylinder and rests on the threaded bushing. A safety catch is connected to the cylinder or the piston and engages either the nut or the threaded bushing.

Abstract: A load alternation counting device for an actuation device that is periodically hydraulically loaded has a cylinder and a piston sealingly positioned within the cylinder and axially displaceable therein. A pressure connector is provided for connecting the cylinder to a hydraulic loading device of the actuation device such that the piston is axially loaded when hydraulic loading of the actuation device occurs. A counter is switchable by an axial displacement of the piston within the cylinder. A spring for biasing the piston in a direction away from the counter is provided. The spring has a spring force such that switching of the counter by the axial displacement of the piston occurs only when a preset hydraulic pressure is surpassed.