Influence of Extra Weight and Tire Pressure on Fuel Consumption at Normal Tractor Slippage

Abstract

Tire pressure and wheel load are both easily managed parameters which play a significant role in tillage operations for limiting slip which involves energy loss. To a great extent, this aspect affects the fuel consumption and the time required for soil tillage. The study was focused on the tire pressure and extra weight variation effect on fuel consumption and work productivity for soil tillage at normal tractor wheels slippage (7-15%). The experimental research unit composed of an 82.3 kW 4WD tractor and a reversible 4-bodies plough is presented. Tests were carried out on a stubble loam, where slip of tractor driving wheels was  15%, tractor front ballast mass was varied in the range from 0 to 520 kg and inflation pressure in the tires from 240 kPa to 100 kPa. Dependences of tractor performance indicators on ballast mass and tires inflation pressure are presented. When tractor tire slip varies in the range from 7 to 15 percent (which is normal slip in the soil), reducing the tires inflation pressure decreases the driving wheel slip and fuel consumption, while increases work productivity. Increasing the additional mass of the tractor (adding ballast weights) decreases the driving wheel slip, increases work productivity, but also increases fuel consumption and soil compaction.

Differences in tractor performance parameters between single-wheel 4WD and dual-wheel 2WD driving systems

“…Most small and medium duty four wheel drive tractors are available with different sizes of their front and rear wheels. Most such 4WD tractors are manufactured in such a way that in static conditions rear wheels would be loaded by 55-65% of the total weight of the tractor (Damanauskas et al, 2015;Janulevičius and Giedra, 2008). Tractor researchers recommend maintaining this proportion of vertical wheel loads in working conditions as well (Janulevičius and Giedra, 2008;Stoilov and Kostadinov, 2009).…”

“…Currently, more and more tractor performance researchers recommend reducing the air pressure in the tires (Š merda and Č upera, 2010; or using dual wheels (Molari et al, 2012;Damanauskas et al, 2015), thus increasing contact area between the tires and the ground. It means that tractor's weight is spread across a larger area, reducing pressure on the soil.…”

“…4 suggests that stubble cultivation in dual-wheel 2WD mode resulted in hourly fuel consumption being lower by nearly 1.2 L h À1 or 7.3% on average as compared to single-wheel 4WD mode for the same slip (8-12%). Based on scientific literature (Zoz and Grisso, 2003;Damanauskas et al, 2015;Elwaleed et al, 2006;Stoilov and Kostadinov, 2009) and the research results, we can assume that in a single-wheel 4WD mode, with varying tire pressures and ballast weights and with the effect of pulling force, minimum rolling resistance for the tractor and rational kinematic mismatch between the front and the rear wheels is not ensured, resulting in higher fuel consumption. Scientific literature discusses the effect of rolling resistance Mardani, 2014b, 2013) and kinematic mismatch Vantsevich and Gray, 2009) on power consumption.…”

“…Fuel consumption for carrying excess weight increases significantly when working speed is increased (Janulevičius and Giedra, 2008;Taghavifar and Mardani, 2014). Analysis of research materials shows that optimal tractor slip in soil should be in the range of 8-12% (Damanauskas et al, 2015;Moitzi et al, 2013;. The wheel slip is a critical parameter for the fuel consumption and the field performance.…”

“…Four-wheel drive tractors with front wheels smaller than the rear wheels are known as MFWD. Since the traction performance of a tractor has a major impact on both fuel consumption and the time required for soil til lage, optimizing this performance is clearly of crucial impor tance in tillage management (Damanauskas et al, 2015;Backman et al, 2013;SAE, 2006). Fuel consumption of the tractor is highly dependent on the engine speed and load characteristics.…”