Influence of Ballast and Tyre Inflation Pressure on Traction Performance of Agricultural Tractors Evaluated in Trials on Concrete Track

As agricultural tractors function under various soil and environmental condi- tions, optimising their design and paraameter settings for enhanced traction performance is essential for maximising their operational efficiency. This study aimed to assess the traction capabilities of standard tractors, ensuring effective operations even under highly demand- ing conditions. A traction load measurement system was refined to collect performance data, and standardised tests were conducted on a concrete track to evaluate key traction metrics. The analysis considered drawbar pull, traction force, travel reduction (slip), and net traction ratio. Two tractors from the same model series, featuring similar design charac- teristics but differing in engine power, were compared. Three primary parameters—tractor mass, tyre pressure, and engine power—were evaluated across six distinct operating condi- tions. Results recorded at forward speeds below 6 km/h indicated that lower tyre pressure led to an increased net traction ratio due to the enhanced drawbar pull. Additionally, an increase in tractor mass contributed to a higher drawbar pull, which, in turn, improved traction force across all speed ranges. The maximum traction force was not significantly affected between 66 kW and 86 kW tractors at speeds up to 4 km/h. Meanwhile, the traction force remained high up to velocities of 6 km/h in the 86 kW tractor. The efficiency (i.e., the ratio between measured and declared power) varied between 64% and 70% for the 66 kW tractor and between 70% and 74% for the 86 kW tractor. The travel reduction was mainly affected by the power of the tractor. The slip caused a reduction close to 4 and 6 km/h for the 66 kW and 86 kW agricultural tractors, respectively. Overall, the proper adjustment of tractor parameters significantly impacted their traction performance, and the findings provide valuable insights for improving tractor designs and field applications.