An automated apparatus calibrates digital torque analyzers that, in turn, are used to verify the accuracies of torque wrenches. The apparatus is located in a central laboratory, and the digital torque analyzers are brought to the laboratory for calibration. Previously, the torque analyzers were calibrated in the field by hanging known dead weights on moment arms of known lengths. That procedure yielded accurate results, but involved transportation and lifting of weights, with risk of injury to technicians. The present apparatus makes it unnecessary to handle weights. Instead, a power jack loads a moment arm via a gearbox and a standard load cell. The apparatus includes a control computer that recognizes the torque analyzer to be calibrated and commands the application of prescribed increments of torque over the range of the torque analyzer. At each increment, the applied torque (calculated from the load-cell reading) is compared with the torque-analyzer reading. When the measurement and comparison have been completed at each increment, the technician presses a button, causing the apparatus to advance to the next increment. When all measurements and comparisons have been completed, the computer prints out the resulting data.
This work was done by Raymond L. Gammon, David W. Kibbey, and Kenneth L. King of United Space Alliance for Kennedy Space Center. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com under the Mechanics category, or circle no. 188 on the TSP Order Card in this issue to receive a copy by mail ($5 charge).