Design, Construction and Test of a Three-point Hitch Dynamometer

For measuring the draft forces exerted by implements into tractor, we use the dynamometers that are divided into pull type or three-point hitch type. For measuring the forces between the tractor and the mounted implements, three-point hitch dynamometers are used. In this research, an adjustable three-point hitch dynamometer with a draft capacity of 25 kN was designed and built which is made up from two frames that one of them placed inside the other. The force sensing elements were comprised of a loadcell that was installed between the frames. All mounted tillage implements were able to be tested by this measuring device excluding mounted implements which are powered by PTO and by using this dynamometer, the variations of implements draft force in the different tillage conditions consist of the various work depths and different forward speeds would be studied. After design and construction steps, dynamometer was calibrated, tested and evaluated. Field tests were done by using of four mounted tillage implements and obtained data were compared by obtained data from ASAE D497.5 standard formula. So with these data, the design of tines, their stems, equipment frames and the selection of the optimal size of the tillage equipments in regard of the soil type of the region and the power of the available tractors will be more scientific and reasonable.