Development and validation of a tractor drawbar force measurement and data acquisition system (DAQ)

Matching agricultural tractors to implements towed by the drawbar is one of the important aspects of machinery management for ensuring optimum performance and fuel cost savings. A field deployable tractor draft force measurement and data acquisition system was developed and evaluated as part of this research project. A drawbar instrumented to measure draft force in field operating conditions was developed and statically calibrated. The drawbar was calibrated by applying loads from 4.45 to 134 kN using a hydraulic cylinder connected to a 444.8 kN load cell. Testing was conducted with the drawbar installed on a tractor on a concrete track. The Nebraska Tractor Test Laboratory (NTTL) load car was used for applying draft loads to evaluate the instrumented drawbar. The track test consisted of seven loads corresponding to maximum power in seven gears. The draft forces as measured by the drawbar were compared to the draft measurements recorded by the load car. The error between draft force measurements of the instrumented drawbar and the load car measurements ranged from 0.21 kN (0.27%) to 0.99 kN (2.88%).There were no statistically significant differences between drawbar and load car measurements confirming that the drawbar force measurement and data acquisition (DAQ) system developed as part of this research can be used for field use.