Importance of automatic variable single hitch point for 2WD tractors - A theoretical analysis

Software is developed in Visual Basic 6 environment for predicting the haulage performance of 2WD tractor. Three types of inputs namely tractor, trailer and operating parameters are required to run the software. Various empirical and theoretical equations were used for predicting the haulage performance parameters such as draft, slip, actual speed, transport productivity, transport efficiency, fuel economy index, front and rear wheel utilization factor etc. In addition to this, the software also gives a warning signal when either stability of tractor or engine power fails. It was used to evaluate the haulage performance by varying the hitch height (HH) at various operating conditions. It was observed that there is a significant increase in the maximum payload 78, 300 and 3300% while HH was lowered from 0.7 to 0.1 m at 0, 5 and 10° slope, respectively. However, the dynamic load on rear axle increased from 1470 to 1730 and 1500 to 1820 kg when HH increased from 0.1 to 0.7 m at 800 and 1000 kg payload, respectively. Further, it was observed that fuel economy index was reduced by 6.3% and engine power requirement by 4.23% at 800 kg payload when HH was raised from 0.1 to 0.7 m. It was observed that stability of tractor increases by lowering the HH, however, traction increases by raising the same. Hence, it was concluded that variable HH can meet the requirements of stability as well as traction during transport as per necessity.