Economical tire on tractors

The hourly consumption of a tractor may vary depending on the type of tire used, radial or conventional, in addition to the amount of ballast used and the tractor's travel speed.

In recent years, due to the increase in demand for food in large cities, agriculture has been modernized in order to obtain maximum productivity. However, to obtain a good result with the machine it is necessary that it is correctly adjusted in order to obtain maximum performance.

Proper handling of the tractor along with its correct maintenance is essential for agricultural companies that strive for mechanization rationalization projects (MIALHE, 1980). This management consists of employing machine systems in technically and economically organized ways, in the execution of operations in the agricultural environment (MIALHE, 1974).

Among the tractor configurations that can be managed in order to improve its performance, we can mention the construction type of tires, tire inflation pressure, liquid and solid ballast, in addition to weight distribution according to the activity to be carried out. carried out (MONTEIRO et al., 2008). The arrangement of these factors influences the operational performance of the machine.

Tires are an important part of the tractor, when the tires are suitable for the machine, in different situations and conditions on the ground surface, they result in better overall performance of the machine, with a consequent increase in operational capacity, better quality of service, lower cost, lower specific consumption and lower impact on soil structural conditions (MONTEIRO, 2008).

The wheelset constitutes the link between the soil-machine interface, it is through it that the main functions of a tractor are carried out, such as: supporting and sustaining the weight of the machine on the surface when carrying out work; direct the machine; be able to move and generate traction effort through the transmission to the support surface of the force produced as a result of the wheelset activation (REIS, 2005).

An experiment carried out through a partnership between the Agricultural Machinery Accident Investigation Laboratory – LIMA and the Agroforestry Machinery and Tire Testing Center (NEMPA), aimed to evaluate the hourly consumption of a tractor depending on the type of tire, liquid ballast and travel speed.

The work was carried out on an agricultural soil track, 400 meters long and 25 meters wide, totaling 10.000 m² of area and slope of 1% lengthwise. The soil in the area was Distroferric Red Nitisol with flat relief.

All tests were carried out with a John Deere, SLC, model 6600 tractor, with 88 kW of engine power, at 2100 rpm, with the auxiliary front traction on.

A platform scale, J-Star Electronics model 6000, with a capacity of 3000 N and accuracy of 1%, was used to determine the individual weight of each tire in order to measure the mass of the tractor.

Two sets of tires were used, both for the rear and front wheels, one set consisting of bias tires and the other consisting of radial tires. The tests were carried out with radial tire inflation pressures of 96,5 kPa (14 psi) on the rear wheels and 82,7 kPa (12 psi) on the front and diagonal tires of 124,02 kPa (18 psi) on the front wheels. and 137,8 kPa (20 psi) on the rear wheels.

To add water to the tires, the tractor was lifted with the help of a jack and the percentage of water in the tires was determined by the position of the filling nozzle in relation to the horizontal. For 0% water ballast, the tire was considered only with an inflation pressure for radial tires of 96,5 kPa (14 psi) on the rear wheels and 82,7 kPa (12 psi) on the front and bias tires of 124,02 kPa (18 psi) on the front wheels and 137,8 kPa (20 psi) on the rear wheels, without adding water. To add 37,5% of water, the nozzle was positioned at an angle of 45^o in relation to the ground at the bottom. To add 75% of water to the tire, the nozzle was positioned at the top. Gears B1, B2 and C1 correspond to speeds of 4, 5 and 7 km/h respectively.

The experimental design used was in bands with a 2x3x3 factorial system referring to two types of tire (radial and diagonal), three gears (B1, B2 and C1) and three liquid ballasts (0%, 37,5% and 75% water) with three repetitions.

Fuel consumption was determined using two flowmeters of the brand and model OVAL M-III LSF41L0-M2, with a flow rate of 1 ml/pulse, installed in the fuel circuit, between the tank and the engine, being installed before the pump. injector and the other on the fuel return from the tank.

Analysis of variance was performed using the 5% F test to evaluate the difference between the means and the 5% Tukey test to compare the means. 

Figure 1 shows the values ​​referring to the breakdown of the interaction between the type of tire and liquid ballast for hourly consumption. Evaluating the data, it can be seen that the type of ballast did not interfere with the hourly consumption of the tires among themselves, that is, in the radial type tire, regardless of the liquid ballast used, the hourly consumption of the tractor will be statistically equal, the same applies to the rotated diagonally. However, comparing the types of tires between them, it is possible to verify that the diagonal tire statistically had a higher consumption when compared to the radial tire for the liquid ballast situation at 37,5% water, this may have occurred because in this amount of water, 37,5 .XNUMX%, the radial tire must have had a better contact surface with the ground, more than for the other ballasts, than the diagonal tire, consequently a lower consumption.

Radial tires as a whole provide better performance than diagonal tires, in addition to producing lower pressure on the ground, for the same applied load, which significantly reduces compaction. The biggest problem faced by radial tires is their high price and also the investment required for tire industries to start production (MONTEIRO E LANÇAS, 2014). 

Figure 2 shows the hourly fuel consumption of the three gears (speeds) evaluated on the tractor. Among the tractor's three gears, B1, equivalent to a speed of 4 km/h, had the lowest hourly consumption statistically, while gear B2 and C1 did not differ statistically from each other, speeds of 5 and 7 km/h respectively, or In other words, it can operate at speeds of 5km/h or 7 km/h and the hourly consumption will be the same, while the speed of 4 km/h will provide fuel savings, consequently better hourly consumption compared to other speeds. Gabriel Filho et al. (2012) state that travel speed directly affects the performance of the set, as it is linked to fuel consumption. Oliveira et al. (2000) also found an increase in hourly fuel consumption with an increase in the speed of the tractor units.

Silveira et al. (2013) report that with an increase in speed there is an increase in rotation on the engine shaft, which means there is a tendency for hourly fuel consumption to increase.

The speed of 4 km/h provided lower hourly fuel consumption compared to the others. The radial tire with 37,5% ballast had lower fuel consumption than the bias tire in the same situation.

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Article published in issue 149 of Cultivar Máquinas.