Static Testing of Draft Sensor for Three Point Hitch Dynamometer Utilization

Abstract

This paper investigates the possibilities in design of universal three point hitch dynamometer. Approaches in different hitch dynamometers are explained and pros and cons are mentioned. Also main parts and functional principle of draft sensor are clarified. The main goal of this research is clarification and examination of draft sensor output signal on angular draft force dependences. Utilization of draft sensor as a source for draft force sensing in lower arms is intended and examined. Research was focused on loading of draft sensor in different directions for proper screening of voltage output. Special loading device was designed and used with respect of real mounting conditions and force loading identically to bearing pins of tractor hitch lower arms. With usage of calibrated load cell and National instrument sensing control unit stage loading diagram of draft sensor was obtained. Results show basic feedback of voltage output on force load angle variation. In non-load condition, voltage output fluctuates around 5 V. In the main direction of draft force application voltage drop occurs from 5 V up to 3.16 V. Reverse direction of loading brings the voltage output increment from 5 V up to 7.06 V. When the load is applied with angular inclination voltage output changes are diminished up to 90° and draft sensor shows voltage output symmetry against the main axis. Based on stage loading diagram the appropriateness of draft sensor usage in design of universal three point hitch dynamometer is discussed in paper summary. Also further research opportunities and results application are suggested.