Dynamic-energetic balance of agricultural tractors: active systems for the measurement of the power requirements in static tests and under field conditions

Abstract

Modern tractors are characterized by the introduction of devices designed to increase the operative performances of the machines, such as systems for monitoring and controlling various functions (through a massive use of electronics and hydraulics), or deputed to improve the comfort of the driver (paying more attention to ergonomics, air-conditioning, noise and vibration). Such devices need energy to be operated, affecting the energetic balance of the tractor. In this context, the availability of suitable methodologies and instrumental systems could be useful to provide objective, accurate and reliable measurements of the performances of the tractors under different conditions, also considering the power requirements from ancillary services and/or simulating the coupling with operating machines. The tests on the performances of tractors are now made using different methods, including the trial codes issued by the OECD Codes. Beyond their undoubted validity, they fix standard test conditions that often do not adequately represent the operative reality, so that, much remains to investigate on the actual performances provided by the tractors. From this point of view and with reference to fixed point tests, a test bench was developed for the measurement of the power required by various devices, such as transmission and air conditioning. It was used in experimental tests on a tracked tractor and on a wheeled tractor, aimed at validating the test device, measuring the power absorption related to the rotational speed of the organs of propulsion and to the characteristics curves, in order to quantify the power drawn by the transmission and by the air conditioning and assess the residual power for other tractor functions. As to field conditions, a study is being conducted at CRA-ING, within the project PTO (Mi.P.A.A.F.), to develop a mobile test bench aimed at evaluating the power required by different operations, such as self displacement, traction, use of power take off, their combination. The system simulates such operations by applying to the tractor, by means of a system of sensors and actuators operated by feedback signals, work cycles combining force of traction, p.t.o. torque, hydraulic power, derived from data recorded during real field test with agricultural machines.

Conventional and Conservation Seedbed Preparation Systems for Wheat Planting in Silty-Clay Soil

“…The dynamometric brake was also used, after the field tests, in order to reproduce the mean conditions of fuel delivery, measured PTO and engine speed. This simulation aimed at evaluating the total torque and power provided by the engine and the corresponding fuel consumption [45].…”

Effects of six primary tillage implements on energy inputs and residue cover in Central Italy

“…The availability of data on energy requirement, fuel consumption and force of traction of tillage implements is the main factor to determine the power class of the required tractor (Moitzi et al, 2013;Pochi et al, 2013) and to estimate the effects of different implements in relation to the quality of the tillage in specific soil types, in terms of depth of tillage, soil cloddiness and crop residue or biomass cover (Raper et al, 2000;Chen et al, 2004;Sahu and Raheman, 2006).…”

“…Conventional tillage systems may produce undesirable effects, such as worsening of soil structure due to compaction, loss of nutrients in deeper layers and of organic matter in upper depths (Lal, 2004), increasing soil erosion caused by wind or by surface runoff (De Laune and Sij, 2012), excessive energy requirements and costs (Perfect et al, 1997). These effects can be reduced, especially in compact clay soil, by replacing conventional implements with soil conservation tillage equipment, to reduce the number of passes, the working depth, the fuel consumption and the energy input (Raper and Bergtold, 2007;Fanigliulo and Pochi, 2011), by using one pass implements with wider working width and equipped with suitable geometry working tools (Godwin, 2007).The availability of data on energy requirement, fuel consumption and force of traction of tillage implements is the main factor to determine the power class of the required tractor (Moitzi et al, 2013;Pochi et al, 2013) and to estimate the effects of different implements in relation to the quality of the tillage in specific soil types, in terms of depth of tillage, soil cloddiness and crop residue or biomass cover (Raper et al, 2000;Chen et al, 2004;Sahu and Raheman, 2006).Studies on conventional and reduced tillage in scientific literature have provided a large amount of information on methods, labour and energy in different soil conditions (Al Suhaibani and Al-Janobi, 1997;Arvidsson et al, 2004;Wandkar et al, 2013), but only a few gave a comprehensive picture of the energy request and of the quality of tillage for the most common methods performing primary tillage in compact soils. McLaughlin et al (2008) studied energy inputs and draft for eight different primary tillage implements in a clay loam soil, but no data on tillage quality parameters were provided.…”

Test Rig and Method for Comparative Evaluation of Conventional and Bio-Based Hydraulic Fluids and Lubricants for Agricultural Transmissions

“…Moreover, the usage time distribution among different agricultural operations is also influenced by the tractor power: increasing the power, tractors are increasingly employed in heavy operations such as primary soil tillage [34]. Finally, different functions can be involved at the same time in the execution of each agricultural operation (e.g., tillage with active implements involves both drive train and PTO, while passive implements only require traction power) [35]. Taking these factors into account, a hypothesis has been formulated (Table 3), relating to the average usage of a 105 kW power tractor with 100 dm 3 of UTTO fluid in the reservoir, in an actual working time of 700 h (approximately corresponding to a year) during which the three functions could have been carried out individually or in combination.…”