Patent ID: 7062998

Claim:
A hydraulic, threaded bolt tightening device for tightening and loosening bolts, comprising a cylinder supported on a machine part, wherein the cylinder is to be clamped by a threaded bolt and a nut tightened onto the bolt, a threaded bush screwed on to one end of the threaded bolt; at least one piston which is guided to move in the cylinder in a sealed manner, and the piston can be pressurized periodically, the piston is supported on the bush; a pressure medium supply to the threaded bolt tightening device, a pressure medium connection from the supply located on the threaded bolt tightening device, an adjusting ring arranged in the cylinder and connected to the nut by a form fit for rotating the nut, a rotary drive for rotating the adjusting ring with a drive connection to the adjusting ring, a rotation angle sensor on the rotary drive for sensing the rotation angle of the rotary drive and thereby of the nut, a control device for driving the pressure medium supply to the threaded bolt tightening device and for causing the rotation of the rotary drive, an input device for entering the pitch of the threaded bolt, and a computer device connected with the rotation angle sensor for converting the rotation angle of the nut, as measured by means of the rotation angle sensor, into the extension of the threaded bolt effected by the threaded bolt tightening device.