A TRIAXIAL DYNAMOMETER FOR FORCE AND MOMENT MEASUREMENTS ON TILLAGE IMPLEMENTS

A dynamometer was designed to measure the forces and moments acting on a tillage implement for use both in a soil bin and in the field. The instrument is able to measure the three orthogonal forces acting on the implement and the three moments acting about the orthogonal axes, up to a maximum force of 100 kN and a maximum moment of 100 kN m. The dynamometer employs two extended orthogonal rings mounted with their axes at right angles and a torque tube. The device was machined from the solid using a high tensile steel. The forces and moments acting on the dynamometer were measured by the use of strain gauge bridges using foil-type gauges. The design criteria of the rings and the torque tube and the arrangement and function of the strain gauge bridges are described in the paper. The dynamometer was calibrated by the application of known forces and moments and the voltage output of the strain gauge bridges was measured. The calibrations showed a high degree of linearity between the applied forces and moments and the bridge outputs. The hysteresis effect between loading and unloading was small, as was the effect of the position of the applied forces from the longitudinal axis of the dynamometer (<2·0%). The interaction of orthogonal forces on the response of a force measuring bridge was generally found to be 4% or less, except in two cases where practical gauging difficulties arose. © 1993 Silsoe Research Institute.