The resulting deformation is recorded by a mechanical dial gauge, and is directly related to the bolt tension force generated. The bolt joint is tightened and slackened using a special torque wrench, which can be set sensitively with the aid of a threaded spindle. The main element of the unit is a slotted, elastically deformable steel block. By tightening the bolt joint, the slotted area is deformed, thereby generating an axial tension force in the bolt. By using an axial bearing, the head friction of the bolt can be largely excluded, so that only the friction of the threaded joint is measured.
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