The invention relates to a nut having an internal thread and two nut parts (1, 2), each of the nut parts (1, 2) having a section of the internal thread which is radially slidable onto an external thread (25), the nut parts (1, 2) having cooperating connecting elements which permit relative displacement of the nut parts (1, 2) in a direction extending radially with respect to the axis of the internal thread until reaching a use position in which the internal thread of the nut engages around the external thread (25) with a small clearance. The connecting elements have guide surfaces (9-20) which guide the nut parts (1, 2) of the nut in a rotational movement about an axis of rotation extending transversely to the axis of the internal thread when displaced into the use position,

wherein each nut part (1, 2) has at least one first locking arm (5, 7) which has on one side a guide surface (9, 11) which induces the rotational movement when the nut parts (1, 2) are displaced and bears against a complementary guide surface (10, 12) on a second locking arm (6, 8) of the other nut part (1, 2).

The nut has a plurality of pressure threads (36-41) which are arranged around the internal thread and receive the pressure screws (26-31) that can be screwed out in the axial direction from a first axial end face (21) of the nut and have a receiving means (35) for a screwing tool in the region of a second axial end face (22) of the nut, wherein at least one pressure thread (36, 39) is arranged in the first locking arm (5, 7), which has the first axial end face (21), and wherein the second locking arm (6, 8) with the second axial end face (22), which cooperates with the first locking arm (5, 7), has a recess (42, 43) through which the pressure screw (29, 26) projects.

A device for tightening a screw connection on a flange connection has a tool carrier movable along the flange connection and provided with a traction drive. A tool on the tool carrier is provided for tightening the screw connection. A control unit is provided to move the tool carrier into a working position by traction drive control signals. The control unit controls, by tool control signals, tightening of the screw connection. On the tool carrier, a holding tool with counter-holding surfaces is arranged. The counter-holding surfaces are provided to bear against the threaded element of the screw connection. The tool carrier has a drive for moving the holding tool between a rest position and a counter-holding position. In the counter-holding position, the counter-holding surfaces bear against the threaded element. The control unit is additionally provided to control the drive of the holding tool by holding tool control signals.

A bolt includes a threaded shaft and a bolt head. The threaded shaft has a first end, a second opposing end, and an external thread. The first end includes a flared protrusion and the external thread is wrapped about the shaft and extends from the second opposing end to the flared protrusion. The bolt head includes an interior threaded bore for threadingly engaging the external thread of the threaded shaft, a front surface, and an opposing back surface having a recess configured to receive at least a portion of the flared protrusion of the threaded shaft therein.

A bolt includes a threaded shaft and a bolt head. The threaded shaft has a first end, a second opposing end, and an external thread. The first end includes a flared protrusion and the external thread is wrapped about the shaft and extends from the second opposing end to the flared protrusion. The bolt head includes an interior threaded bore for threadingly engaging the external thread of the threaded shaft, a front surface, and an opposing back surface having a recess configured to receive at least a portion of the flared protrusion of the threaded shaft therein.

A fastener includes: a shaft having longitudinal axis and a first and second threaded portions, the first and second threaded portions separated by a central portion having a reduced diameter between the first and second threaded portions, and at least one of the first or second threaded portions is chamfered to reduce friction on leading threads.

A fastener includes: a shaft having longitudinal axis and a first and second threaded portions, the first and second threaded portions separated by a central portion having a reduced diameter between the first and second threaded portions, and at least one of the first or second threaded portions is chamfered to reduce friction on leading threads.

A fastener includes: a shaft having longitudinal axis and a first and second threaded portions, the first and second threaded portions separated by a central portion having a reduced diameter between the first and second threaded portions, and at least one of the first or second threaded portions is chamfered to reduce friction on leading threads.

A fastener includes: a shaft having longitudinal axis and a first and second threaded portions, the first and second threaded portions separated by a central portion having a reduced diameter between the first and second threaded portions, and at least one of the first or second threaded portions is chamfered to reduce friction on leading threads.

A monitoring device for monitoring a screw joint of an object includes a base plate to be attached to the object and a top plate to be attached to one part of the screw joint, wherein the base plate and the top plate are positioned parallel to and on top of each other and wherein both plates each includes at least one electrode that capacitively interact with each other. The monitoring device is characterized in that the electrodes are shaped and positioned such that at least one electrode of one of the plates interacts with at least two different electrodes of the other one of the plates depending on the rotational position of the plates relative to each other. A monitoring arrangement having at least one monitoring device of this kind and a monitoring method are also provided.

Tightening device can fasten a fastening element by a target tightening force with good accuracy and facilitate automation. The tightening device includes a cylindrical drive socket holding a nut in the lower end opening thereof; a nut holder disposed inside the drive socket, a bolt passing through a bottom thereof, and regulating movement of the nut held by the drive socket toward the tip end of a threaded par; a tension rod which is disposed inside the nut holder and the lower end face of which has a threaded hole into which a portion of the threaded part that is further on the tip end side than the nut is screwed; a sensor for detecting tension force; a first motor for turning the tension rod around an axis that extends in the vertical direction; and a second motor for turning the drive socket around an axis.