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TM 320 Screw connections testing



  • Correlation between tightening torque and tension force on standardised bolts
  • Breakaway torque of a bolt joint


Technical Description

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. 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. 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.

The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

Learning Objectives / Experiments
- axial tension force in a bolt joint dependent on the tightening torque or the elastic deformation of a slotted block
- measurement of the breakaway torque, including for different fitting situations of the bolt joint
- measurement of thread friction and overall friction


[1] experiment on the correlation between the tension force and tightening torque of bolts
[2] bolt size M8x100, wrench jaw size 13mm
[3] elastic deformation of a slotted block by the bolt
[4] determining the tightening and breakaway torque with a mechanical torque measuring device 
[5] 2 position dial gauges 
[6] sensitive torque setting by hand wheel

Technical Data
Tension force: max. 40kN
Force/travel constant: 20kN/mm (on slotted block)
Max. tightening torque: 40Nm
Torque/travel constant: 10Nm/mm (on torque measuring device)
Position dial gauge: 0...10mm, graduations: 0,01mm

Dimensions and Weight
LxWxH: 450x400x260mm
Weight: approx. 27kg

Scope of Delivery
1 bolt tester complete with switchable ratchet, 1 set of bolts in transparent container, 1 set of instructional material

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