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10. Torque

Siegfried Herbold

The Technical Committee “Torque” deals with questions regarding the realization and measurement of the physical quantity of torque, i.e. “pure torque” (also represented as moment of a force couple) and “torque with cross force” (to be seen as moment of a single force). The former occurs, for example, in drives with a negligible influence of cross forces or bending moments. The latter is the typical application case of a torque wrench where a torque is generated with the help of a cross force that acts on the lever; on this occasion, however, the introduced force as well as usually also an additional bending moment are involved, in addition to the torque. The tasks of the Technical Committee include the preparation of calibration standards and guidelines for the quantity of static torque, the technical consultation on issues in the field of torque measurement, the organization and evaluation of interlaboratory comparisons and the exchange of experience among its members, which are usually accredited calibration laboratories for this measurand. The Technical Committee “Torque” develops drafts for DKD guidelines.

In addition, members of the Technical Committee also support standardization bodies, such as DIN and VDI, with their expertise. The expert reports serve the gathering and transfer of knowledge for the realization and dissemination of the quantity of torque. Comparison measurements are an important element in the evaluation of the calibration capabilities of accredited laboratories in the field of torque. The Technical Committee currently has 41 members, including nearly all of the more than 30 accredited laboratories for torque calibration.  Currently, the Technical Committee is revising the guidelines DKD-R 3-7 and DKD-R 3-8 for the static calibration of indicating torque wrenches as well as calibration devices for torque wrenches. In addition, an interlaboratory comparison for the calibration of indicating and clicking torque wrenches according to DIN EN ISO 6789 is in the process of being completed. A report on the previous interlaboratory comparison for the calibration of torque transducers according to DIN 51309 is ready for publication. In February 2014, the Technical Committee organized a seminar on measurement uncertainties in torque realization and torque measurement for the employees of accredited laboratories (276th  PTB Seminar).

The Technical Committee has already published the following calibration guidelines: • DKD-R 3-5: Calibration of torque measuring devices for static alternating torque • DKD-R 3-7: Static calibration of indicating torque wrenches • DKD-R 3-8: Static calibration of torque tool calibration devices