Torque Arms and Errors: Quantifying Overhung Load in Torque Calibration
Overhung load, the bending of a torque transducer caused by the weight of an unsupported single-ended arm and its deadweights, is one of the most underestimated of all torque errors in calibration, and it is invisible on raw calibration data. This paper shows how to quantify that bending where the standard double-loading test cannot be run, carrying a real 1 000 N·m single-ended arm measurement through to a worked verification against a primary deadweight standard. The analysis demonstrates that bending can dominate the combined variance in an unsupported-arm setup, and that a single mechanical choice, a more bending-insensitive transducer or a bearing-supported arm, can cut expanded uncertainty several-fold while clarifying what ASTM E2428 and BS 7882 actually require. If torque arms and errors are part of your calibration work, download the full paper for the methods, the uncertainty budgets, and the practical guidance on when a single-ended arm is defensible and when it isn't.
Read the guidance document here.
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