Torque reaction in angled nutrunners.
In the process of tightening a joint, the angled nutrunner acts on the operator with a torque reaction in the final stages of the tightening sequence. In the following series of experiments, the torque reaction of a machine acting on various joints is studied. A distinctive feature of the torque reaction is that the handle of the angled nutrunner causes a rapid displacement. The amplitude and time aspect of this displacement depend on the stiffness of the joint (whether it is hard or soft), and the movement of the handle depends on how the operator is holding it. How the operator responds to the torque reaction depends upon, among other things, the displacement amplitude as well as the torque level of the machine. Because of this, the displacement amplitude can be used as a measure of the operator's discomfort.
Lindqvist
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R&D Applied Ergonomics, Product Safety and Liability, Atlas Copco Tools AB, Box 90 111, S-12021 Stockholm, Sweden.