A theoretical and experimental study of the traction properties of agricultural gantry systems

Saabunud / Received 12.04.2020 ; Aktsepteeritud / Accepted 18.05.2020 ; Avaldatud veebis / Published online 18.05.2020 ; Vastutav autor / Corresponding author: Jüri Olt e-mail: [email protected] movement conditions experienced by an agricultural gantry system along the solid and level ground surface of permanent artificial tracks must make it possible to generate most of its maximum tractive force. Concurrently, the adhesive ability of the agricultural gantry system on the ground surface of such permanent artificial tracks must be sufficient to generate nominal drawbar pull when working at a certain level of slip. This means that there exists the need to seek out the following compromise: the maximum slippage experienced by the wheeled chassis of an agricultural gantry system must be such that, in a situation in which the level of adhesion with the surface of permanent artificial tracks is suitable, it will be able to generate the maximum possible tractive force. The effect of the parameters that involve an agricultural gantry system's wheels – and the physical and mechanical properties of the ground surface along which they move – on potential slippage has not yet been sufficiently studied. This effect cannot be taken into consideration without taking into account the dynamics of any rolling resistance being offered by the agricultural gantry system's chassis. The purpose of this particular study is to research the traction properties of an agricultural gantry system's wheeled chassis in terms of its movement along compacted and level ground upon which have been mounted permanent artificial tracks. The research determines that the wheels of such an agricultural gantry system that are rolling along permanent artificial tracks suffer less slippage and therefore generate a higher level of tractive force. As a result, the agricultural gantry system loses less of its speed of movement and, therefore, uses less energy in that movement. When an agricultural gantry system moves across an agricultural field that has been prepared for sowing, the research also determines the maximum tractive force that its wheels can develop when the adhesion coefficient is set at a figure that is between 0.22–0.24. Once such movement begins along permanent artificial tracks, this coefficient decreases to between 0.15–0.17. An agricultural gantry system's wheels are able to generate a higher level of tractive force when moving along on permanent artificial tracks. This figure is at least 30% higher when its movement has to be considered across an agricultural field that has been prepared for sowing

A theoretical and experimental study of combined agricultural gantry unit with a mineral fertiliser spreader

Saabunud / Received 06.07.2020 ; Aktsepteeritud / Accepted 03.08.2020 ; Avaldatud veebis / Published online 03.08.2020 ; Vastutav autor / Corresponding author: Jüri Olt e-mail: [email protected] to apply mineral fertilisers to the soil are an important part of practically every form of agricultural technology. The current global trend of transitioning to bridge and gantry-type agricultural systems leaves the unanswered relevant question of the effectiveness of the technological process of applying mineral fertilisers to the soil. This is relevant because, in gantry agriculture, a section of the arable soil is separated as an engineering area. This is why the main difference in gantry agriculture from traditional methods of the bulk spreading of fertiliser onto a field is that, with gantry systems, the amount of fertiliser that lands within the engineering zone are limited. This significantly affects the manufacturing costs involved in the entire area of agricultural technology and, as a result, the production costs of the end product. This study aimed to research the patterns that are apparent in affecting the parameters involved in the use of gantry-type equipment when applying fertiliser with the parameters and operational modes of a specially-developed electric spreader of mineral fertilisers. The physical object of the study was the agricultural gantry equipment that had been developed by the authors. This equipment, which is used for spreading fertiliser, was in the form of a tractor-mounted, suspended, single-disc spreader which was known as JarMet, and which had especially been modified to run from an electrical supply. The study indicated that the biggest influence on the speed of rotation of the centrifugal disc in the mineral fertiliser spreader stems from its height above the ground, the distance of track of the agricultural gantry itself, and the aerodynamic coefficient of the fertiliser. It was determined that, for the agricultural gantry with a distance of tracks of 3.5 m, a sufficient angular speed of the single-disc centrifugal tool is 15.5 rad·s−1, with a power demand for driving this at 0.35 kW·h. When using agricultural gantries of this type with an extended track width of up to 6 m, the necessary angular speed of the centrifugal tool for spreading fertiliser increases exponentially, to 318.2 rad·s−1, with the power demand for driving it increasing to the third power

A study of the interaction between soil and the pneumatic wheels of agricultural gantry systems

Saabunud / Received 08.02.2020 ; Aktsepteeritud / Accepted 05.03.2020 ; Avaldatud veebis / Published online 07.03.2020 ; Vastutav autor / Corresponding author: Jüri Olt e-mail: [email protected] the stage at which agricultural gantry systems are being designed, developed, and studied, the question of a rational choice of tyres for such systems is relevant, as tyres are the most important part of an agricultural gantry system and have a significant effect on most of its operating properties. The methods that can be used for choosing tyres for traditional mobile-powered equipment are already well established by scientific experience, but the movement of agricultural gantry systems in permanent artificial tracks creates somewhat different conditions and demands for a pneumatic tyre when compared to a traditional tractor moving along agricultural soil. This is why the development of methods that will assist in finding rational parameters for the pneumatic tyres of agricultural gantry systems that are moving along compacted soil in permanent artificial tracks is an urgent and relevant task. The purpose of the study is to optimise the parameters for the tyres of agricultural gantry systems in terms of their being able to travel on compacted soil in permanent artificial tracks. Theoretical studies and the synthesis of the parameters for a pneumatic wheel to work with an agricultural gantry system took place by modelling on a PC the performance conditions of such a vehicle. The basis for the study methods was formed by the fundamentals of tractor theory and theoretical mechanics, using the software program Mathcad. The traction factor of an agricultural gantry system's pneumatic wheel was used as the performance criterion for the effectiveness of the work being done by the wheel. The physical object of study was an agricultural system that has been developed by us. As a result of the study, it was determined that the solving of the task that has been set out - using an analysis of partial derivates of the function of the efficiency of an agricultural gantry system's wheel – makes it possible to quickly and effectively determine the rational optimum points for its pneumatic tyre's parameters. It was determined that, for the agricultural gantry system at hand, and in view of the maximum efficiency of its pneumatic wheel, the wheel's tyre width must be within the range of 0.20–0.30 m and its diameter must be within the range of 0.90–1.25 m. With those ranges, it is recommended that the tyre's inflation pressure be increased from 100 kPa to 160 kPa because the partial derivates of the function of the efficiency at those parameters would decrease to near zero. It has been proven that the choice of tyre type for agricultural gantry systems should be based first on the choice of its width and then its load-bearing capacity – its diameter. The proposed methods for finding rational parameters for pneumatic wheels make it possible to determine the tyre parameters for all kinds of agricultural gantry systems which will be required to travel on compacted soil in permanent artificial tracks. For the agricultural gantry system that has been developed by us, using tyres of the 9.5R32 type provides the highest levels of efficiency, i.e. at a factor of 0.86

Theoretical background for increasing grip properties of wheeled tractors based on their rational ballasting

ArticleSaabunud / Received 30.07.2019 ; Aktsepteeritud / Accepted 07.10.2019 ; Avaldatud veebis / Published online 15.10.2019 ; Vastutav autor / Corresponding author: Jüri Olt e-mail: [email protected] correct selection of the level of mechanical ballasting for wheeled tractors is among the most important issues for increasing their utilisation efficiency, in particular, increasing their grip properties. The shortcoming of the earlier undertaken investigations was that they virtually did not take into account the allowed maximum pressure of the tractor’s wheels on the soil. At the same time, little attention was paid to the impact of the maximum load-carrying capacity of the wheel tyres. The aim of the paper is to eliminate these deficiencies. Because of the authors’ efforts, the new technique has been developed, which differs in that it employs the requirement of the tyre’s ecofilic properties. The implementation of this requirement implies setting the maximum allowed level of the tractor wheels’ pressure on the soil and taking into account the maximum load-carrying capacity of the wheel tyres as well as the vertically applied load on each of the tractor’s axes under the simultaneous action of both the horizontal and vertical components of the tractive resistance of the employed agricultural implement. The practical effectiveness of the new approach is shown by the example of determining the possibility and level of ballasting the specific wheeled tractor operating as part of a ploughing unit

Study of the steering of a wide span vehicle controlled by a local positioning system

Controlled traffic farming allows to minimize traffic-induced soil compaction by a permanent separation of the crop zone from the traffic lanes used by wide span tractors. The Authors developed an agricultural wide span vehicle equipped with a skid equipment for turning and an automatic driving system prototype based on a laser beam. The aim of this work was to study the kinematic conditions that control the steering of this machine. Furthermore, the accuracy and the maximum delay time of the signal transmission by the automatic driving system of the set-up was also assessed. In comparison with crawler tractors, the turning of the agricultural wide span vehicle needs a smaller difference in the moments applied to its right- and left-side wheels. For the predetermined accuracy of the beam position relative to the plant rows, ±ds = ±0.025 m, the accuracy of the direction of the laser beam at a distance S=200 m should not be more than ±0.07° and ±0.0014°, considering a run length of 1000 m. Furthermore, at a speed V=2.5 m s–1 a trajectory deviation φ≤5° requires a topmost delay time of the control signal of Δtmax=0.11 s is required

Experimental research into operation of potato harvester with rotary tool

Saabunud / Received 04.05.2021 ; Aktsepteeritud / Accepted 07.06.2021 ; Avaldatud veebis / Published online 07.06.2021 ; Vastutav autor / Corresponding author: Jüri Olt [email protected] experimental research was carried out on a specially designed laboratory-and-field test unit with the use of a hydraulic vertical rotor drive and strain-gauge equipment mounted on a tractor as well as the set of interchangeable coupling pieces for setting the machine's operating duty. Research into the process of breaking two adjacent potato row beds with the vanes of a vertical rotor has been undertaken. A design and process schematic model has been proposed for the operation of the potato harvester. Experimental research into the geometrical parameters of the potato row has been carried out to select the design parameters of potato harvesters. Based on the results obtained during the experimental investigations, the rational ranges have been established for the work process of the rotary potato harvester, the methods of engineering clod breaking tools have been developed. Following the completion of the full factorial experiment, regression functions have been generated. Their analysis has proved that the following factors have the greatest impact on the optimisation parameters: the rotor diameter and the clearance between the rotor and the spherical discs. The following parameters have been optimised based on the response surface analysis: soil separation ratio S = 93.5%, tuber damage rate Pb = 0.97%, total power consumption by unit operation Nа = 18.27 kW, at the following pre-set values of the factors: nр = 77 min–1, Vm = 2.2 m∙s–1, dр = 0.825 m, l2 = 0.3 m. The maximum discrepancy between the results of the theoretical and experimental investigations for determining the design and process parameters of the potato harvester does not exceed 15%. The completed economic testing has proved the advantages of the experimental potato harvester as compared to the existing ones. That said, the separation ratio of the pilot machine is equal to S = 91.4%, which is 23% higher than in the reference case, while its tuber damage rate is equal to 1.14%, which is 5.0% better than in the reference case. The recommendations for the selection of the rational operation duty of the rotary potato harvester as well as the methods for the engineering analysis of the design and process parameters of clod breaking tools have been developed

The effect of a lateral airflow created on nozzle tip on the spray droplets deposition

Saabunud / Received 02.09.2021 ; Aktsepteeritud / Accepted 11.12.2021 ; Avaldatud veebis / Published online 11.12.2021 ; Vastutav autor / Corresponding author: Jüri Olt [email protected] application efficacy of a plant protection products by using a pneumatic device to change the dispersion of spray droplets is depended on the intensity of crosswind. The laboratory investigations of the spraying process of plants by means of the nozzles of a pneumatic system determined the quality indicators of pressure in the injection process of 0.4 MPa – the droplet coating density of 19–46 pcs cm2 –1 for the weighted mean droplet diameters (WMD) in the other experimental variants was within 304–543 μm. These indicators were compared with those for the standard, anti-drift and air injection nozzle types in which the droplet coating density was 23–59 pcs cm2 –1 and the weighted mean droplet diameters (WMD) were in the range of 350 to 485 μm. An analytical dependence was obtained of the influence of the lateral airflow and air pressure in the pneumatic system upon the amount of the deposited spray liquid

A New Spiral Potato Cleaner to Enhance the Removal of Impurities and Soil Clods in Potato Harvesting

Sustainability in the agricultural field suggests the conservation and maintenance of a natural environment of soil. Nevertheless, in the potato production chain, the mechanized harvest is carried out with the concurring removal of impurities and fertile soil. The authors have developed a new spiral potato cleaner which is able to capture and efficiently remove soil lumps of various sizes and shapes, as well as various plant residues. Theoretical and experimental studies have been performed on this soil clod cleaner to determine the structural and kinematic parameters that provide efficient capturing, motion and sifting down of the soil, through the gaps between the helices of its cleaning spirals. An analytical description of the motion of the clod of soil has been made and a system of differential equations has been compiled, whose numerical solution made it possible to determine the indicated reasonable operative parameters of the developed spiral potato cleaner. The results of the experimental research confirmed those ones obtained through the numerical solution of the mathematical model, i.e., rational angular speed ω of the rotation of the spirals from 20.0 to 30.0 rad s−1 and the radius R of spirals between 0.12 and 0.15 m

Theory of Vibrating Lifting Tools of Sugar Beet Harvesters

The cultivation and harvesting of sugar beets (roots and haulm) is one of the most labour and energy consuming work processes in the agricultural industry. The improvement of the qualitative indicators of the sugar beet harvesting process as the final operation in the work flow of its production represents a multi-faceted research-and-engineering problem, which is to be solved basing on the search for new implement design concepts and overall beet harvester design layouts, the thorough theoretical substantiation of their design and process parameters, the experimental verification of the completed theoretical research with the ultimate objective of the analysis and synthesis of their rational parameters. Theoretical research must play a fundamental role in the mechanical and technological substantiation of the root lifting process. It must be used as the basis for developing rational kinematic and dynamic operation conditions in order to achieve the required quality of the performed work process as well as the streamlined energy consumption. The book can be considered as one of the first solid analytical studies of the process of vibrational digging of sugar beet roots. It offers the analysis of up-to-date engineering solutions of vibrational digging tools and experimental investigations of the first vibrational lifters, the equation of oscillating motions of digging shares

Theoretical study to determine the standard size range of agricultural tractors

Since the tractor is the main energy source in agriculture, the state with highly developed agrarian production, tractor and agricultural machine building should have a fairly clear and consistent policy in the field of organizing the production and supply to agricultural producers of a wide range of tractors for various purposes. Such a policy is based on the type of mobile energy resources, i.e. tractors, based on a deep analysis and study of the volume of agricultural production, the needs for mechanized technologies, the theory of the operation of agricultural machines, the overall assessment of the development of high-tech agriculture. The purpose of this study is to develop theoretical bases for calculating the type of agricultural tractors based on an optimization of technical and economic analysis, taking into account the need for a qualitative and timely implementation of the entire closed set of works in agricultural production. During the research methods of machine use in agriculture, higher mathematics, economics, compilation of programs and numerical calculations on PC were used. The results of the study showed that the classification of tractors should be carried out not according to traction power (as is done in most countries of the world), but by the nominal traction force developed by them. It has been established that this gives a more accurate representation of the operational properties of an energy tool, which in turn allows for the very accurate and correct selection of complexes of appropriate agricultural machinery and implements for its effective operation. The presented theoretical approaches allow to determine with a high degree of accuracy the type of agricultural tractors for any country