A tensioning device for tensioning a workpiece includes a main body having a chamber, a fluid inlet providing fluid communication between a fluid source and the chamber, a puller member supported in the main body and configured to engage the workpiece, and a piston positioned in the chamber and coupled to the puller member. Movement of the piston moves the puller member along a piston axis in at least a first direction. The tensioning device further includes a sensor coupled to the piston and operative to measure a displacement of the piston and/or the puller member in a direction parallel to the piston axis. The sensor generates a signal indicative of the displacement.

The invention concerns a rod tensioning device having a first actuator, at least a second actuator and a tubular support sleeve dedicated to radially surround a threaded rod. Each of the actuators provides a cylinder, and a piston sliding in the cylinder and forming with the cylinder an annular chamber dedicated to be supplied with pressurized fluid. According to the invention, the at least second actuator is temporary axially arranged between the first actuator and the tubular support sleeve for a temporary blockwise assembly, the pistons of two axially adjacent actuators being indexed in rotation together.

The invention concerns a rod tensioning device having a first actuator, at least a second actuator and a tubular support sleeve dedicated to radially surround a threaded rod. Each of the actuators provides a cylinder, and a piston sliding in the cylinder and forming with the cylinder an annular chamber dedicated to be supplied with pressurized fluid. According to the invention, the at least second actuator is temporary axially arranged between the first actuator and the tubular support sleeve for a temporary blockwise assembly, the pistons of two axially adjacent actuators being indexed in rotation together.

A clamping device for expanding a threaded bolt is provided with a support pipe supported against an underlay surrounding the threaded bolt. A cylindrical housing arranged in extension of the support pipe has a piston movable in longitudinal direction and connectable to a hydraulic supply. A changeable bushing is axially carried by the piston and is provided with an inner thread and a radially expanded portion. A resilient arrangement is arranged around the bushing and acts axially on the piston. A lid is secured to the housing. The other support of the resilient arrangement is provided on the lower side of the housing. The lid has a lid base member and a closure lid. The lid base member is provided with an opening closable by the closure lid. The radial extent of the opening is greater than the radial extent of the radially expanded portion of the bushing.

A clamping device for expanding a threaded bolt is provided with a support pipe supported against an underlay surrounding the threaded bolt. A cylindrical housing arranged in extension of the support pipe has a piston movable in longitudinal direction and connectable to a hydraulic supply. A changeable bushing is axially carried by the piston and is provided with an inner thread and a radially expanded portion. A resilient arrangement is arranged around the bushing and acts axially on the piston. A lid is secured to the housing. The other support of the resilient arrangement is provided on the lower side of the housing. The lid has a lid base member and a closure lid. The lid base member is provided with an opening closable by the closure lid. The radial extent of the opening is greater than the radial extent of the radially expanded portion of the bushing.

A hydraulic tensioner (1), comprising: abase (2); a piston (3) mounted for sliding motion relative to the base (2), the base (2) and the piston (3) defining a pressure space (4) therebetween and being arranged to be urged apart along an axis (8) upon introduction of a fluid into the pressure space (4), the tensioner (1) having an internal bore (6) along the axis (8) having first and second ends along the axis and comprising a threaded component having an internally threaded portion (7) at the first end and coupled to the piston (3); the tensioner (1) further comprising: a threaded stud (10) having an exterior thread which engages the internally threaded portion (7) of the threaded component; and a drive mechanism (12) arranged to transmit rotational motion from the second end of the internal bore (9) to the threaded stud; the tensioner being arranged such that rotational motion applied to the drive mechanism (12) at the second end causes rotation of the stud (10) relative to the threaded component, with the engagement of the exterior thread of the stud (10) and the internal thread of the threaded component causing the stud to move along the axis as it rotates.

A hydraulic tensioner (1), comprising: abase (2); a piston (3) mounted for sliding motion relative to the base (2), the base (2) and the piston (3) defining a pressure space (4) therebetween and being arranged to be urged apart along an axis (8) upon introduction of a fluid into the pressure space (4), the tensioner (1) having an internal bore (6) along the axis (8) having first and second ends along the axis and comprising a threaded component having an internally threaded portion (7) at the first end and coupled to the piston (3); the tensioner (1) further comprising: a threaded stud (10) having an exterior thread which engages the internally threaded portion (7) of the threaded component; and a drive mechanism (12) arranged to transmit rotational motion from the second end of the internal bore (9) to the threaded stud; the tensioner being arranged such that rotational motion applied to the drive mechanism (12) at the second end causes rotation of the stud (10) relative to the threaded component, with the engagement of the exterior thread of the stud (10) and the internal thread of the threaded component causing the stud to move along the axis as it rotates.

A hydraulic tensioning apparatus for tensioning a threaded member (2) having a thread, comprising: a hydraulic tensioner (1), having a body (4) and a pressure space (13) for hydraulic fluid and having a thread engaging member (7) arranged to engage the thread of the threaded member (2) and to be urged away from the body (4) on introduction of hydraulic fluid into the pressure space (13) so as to tension the threaded member (2); a displacement sensor (11, 12) arranged to measure a linear displacement of the thread engaging member (7) relative to the base (4) and to provide an output indicative of the linear displacement; a rotation sensor (65, 66) arranged to determine a rotation of a nut (3) rotating on the threaded member (2) and arranged to produce output indicative of a rotation angle of the nut (3); and a control unit (80) arranged to take as inputs the outputs of the displacement sensor (11, 12) and the rotation sensor (65, 66), and to determine from the output of the displacement sensor (11, 12) a required angle of rotation of the nut (3) which accommodates for extension of the threaded member (2) due to being tensioned by the hydraulic tensioner (1).

A hydraulic tensioning apparatus for tensioning a threaded member (2) having a thread, comprising: a hydraulic tensioner (1), having a body (4) and a pressure space (13) for hydraulic fluid and having a thread engaging member (7) arranged to engage the thread of the threaded member (2) and to be urged away from the body (4) on introduction of hydraulic fluid into the pressure space (13) so as to tension the threaded member (2); a displacement sensor (11, 12) arranged to measure a linear displacement of the thread engaging member (7) relative to the base (4) and to provide an output indicative of the linear displacement; a rotation sensor (65, 66) arranged to determine a rotation of a nut (3) rotating on the threaded member (2) and arranged to produce output indicative of a rotation angle of the nut (3); and a control unit (80) arranged to take as inputs the outputs of the displacement sensor (11, 12) and the rotation sensor (65, 66), and to determine from the output of the displacement sensor (11, 12) a required angle of rotation of the nut (3) which accommodates for extension of the threaded member (2) due to being tensioned by the hydraulic tensioner (1).

A sealing device for a hydraulic assembly wherein hydraulic fluid is contained in working chamber (53) formed between body (52) and thrust member (51) of the assembly. The device comprises annular seal (63) with opposed sealing faces which are urged into sealing engagement between body (52) and thrust member (51) which have convergent sealing faces. The device may also have a pressure relief valve (100) tapped into the over-stroke end of chamber (53) to protect seal (63) from over-stroke damage comprising porous body (101) which allows fluid to bleed from chamber (53) and allows seal (63) to pass the tapping point without obstruction.