Variable rate application accuracy of a centrifugal disc spreader using ISO 11783 communication data and granule motion modeling

Hydraulic power transfer and management systems are widely used in modern agriculture, especially in agricultural engineering and the associated processing industry. They can be very simple, but also extremely complex, when precise matching of the interaction of their components in real time is very difficult to controll and achieve. In addition, the designs of a number of hydraulic components is sufficiently complicated for detailed representation on the corresponding hydraulic installation. In all cases, analyzing the performance characteristics of components and the entire hydraulic system, as well as understanding the structure of the hydraulic system, is of great importance. One of the generally accepted ways to facilitate and speed up these processes is the application of schematic diagrams of hydraulic systems and their subcircuits. Officially, hydraulic symbols are defined by ISO industry standards. Therefore, ideally, all hydraulic schemes should be configured using universal graphic symbols. Unfortunately, this is not always the case in technical practice. Depending on the manufacturer and/or dealer of the hydraulic equipment, the symbols of the associated schemes vary in a smaller or a greater extent. The real reasons for the existence of these differences can only be assumed. According to some authors, companies want their drawings to differ from the hydraulic schema of competitors. Therefore, the most commonly used hydraulic symbols are presented in this paper.

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Hydraulic Symbols – Part One: General Symbols and Symbols of Measuring Instruments and Indicators

At the current level of technological development, it is widely accepted that survival and progress of modern agricultural technology (among other things) is based on the widespread application of electronically controlled hydraulic systems, supported by mechanical elements of power transmission and control. This paper is a logical continuation of the first part, entitled "Hydraulic symbols - part I: general symbols and designations of measuring instruments and indicators". Therefore, the current second part of the paper is devoted to the presentation and description of hydraulic symbols of pumps and various types of actuators: linear, rotary and oscillatory. Symbols of the combined-function devices, which can optionally function in two different operating modes, such as pumps or motors, are also shown. Standard symbols of all groups of hydraulic components, which are in the focus of this paper, are standardized and defined by ISO industry standards.

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Hydraulic Symbols – Part Two: Pumps and Actuators

Similar to human health, the importance of hydraulics sometimes becomes apparent only in her absence. Images and motives of agricultural workers from the past times and centuries can look attractive only on paintings of arts. In reality, it was a very hard and sometimes quite dangerous job. The introduction of hydraulics in construction of modern farming machines, agriculture is less demanding for all farm workers, but also more efficient, which is of particular importance for providing enough food for the growing world during the 20-th century. Achieving high efficiency, reliability and long service life of these systems requires sophisticated diagnostics and failure repairment, regular maintenance and careful use of each hydraulic system, and this is only possible with a good knowledge of the functional principles of all elements, their connections and the whole system. However, modern hydraulic systems of agricultural machines are often very complicated, and the construction of their components is too complex for detailed graphic representation within the whole corresponding hydraulic installation. Therefore, instead of detailed representation of the components, schematic diagrams are used. This manuscript represents a logical continuation of the first and second parts of the paper, devoted to the general symbols, labels of measuring instruments and indicators (part one), as well as pumps and actuators (part two). The third) part of the paper presents the hydraulic symbols of the system control elements - hydraulic valves. The graphical symbols of these components are defined by ISO standards.

https://scindeks-clanci.ceon.rs/data/pdf/0554-5587/2019/0554-55871903001P.pdf

Hydraulic symbols: Part three: Valves

Modern agricultural engineering involves the wide application of hydraulic and pneumatic systems for the transmission of power (energy) and control signals. This paper presents the most commonly used types of valves in hydraulic systems. In the literature, more classification of hydraulic valves is reported, according to their construction, purposes, etc., which, even within the same classification criteria, sometimes strongly differ one from the another. Therefore, this presentation is organized by principled valve assignment into four basic groups based on purpose, although there are other divisions according to the purpose of the valve. Other classifications, although present in the available literature, have not been commented in detail, due to space constraints. In this manuscript, the basic elements of the construction of the most important types of valves are described and analyzed, their most important characteristics are described, the base functional principles and technical limitations described, and the given guidelines and recommendations for their optimal application.

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Control components of hydrostatic and hydraulic systems: The valves

The paper presents and analyzes the hydrostatic transmission of power and motion. The most important elements of this group of systems and the possibilities of their application in agricultural technology are given. Particular attention is paid to the positive-displacement pumps that have the widest application in agricultural machinery: gear pumps with external and internal gears, vane pumps, piston-axial pumps with inclined swash plate and piston-axial pumps with inclined cylinder block. Two hydrostatic power transmission and control systems are also presented. The first is a very simple mechanical- hydraulic system of automatic leveling of self-propelled berry fruits harvester. In contrast, the other hydrostatic system is very sophisticated. It is implemented as a very complex combination of hydrostatic and mechanical power transmission subsystems, with the accompanying control digital electronic system, and is intended for the wheat harvester propulsion and steering.

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Hydrostatic Transmission Systems of Power and Motion

At present, spreading of mineral fertilizers in Europe is most commonly performed using centrifugal disk spreaders with attached vanes. The motion of an ideal spherical homogeneous fertilizer particle along the straight vane attached to a flat rotating disc was analyzed in this paper. The analysis was performed in the non-inertial reference coordinate system. From the assumptions introduced to enable analytical describing of the real particle motion as well as the general tools of solid mechanics, the ordinary in-homogenous second-order differential equation having constant coefficients arose. Its solution represents an approximation of the real relative motion of the fertilizer particle along the straight radial vane fixed to the flat horizontal disc rotating at a constant angular velocity. However, the solution of this kind can be very useful for the optimization of centrifugal spreader working parameters.

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On the fertilizer particle motion along the vane of a centrifugal spreader disc assuming pure sliding of the particle

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Hydraulic symbols: Part five: Auxilliary componets

Efficient transmission of energy from arbitrary types of primary sources and/or energy converters towaward appropriate control units and/or consumers can be a more or less complex process. In analogue to other existing branches of modern technology, energy transfer in agricultural machinery needs to be carried out very carefully, applying optimized technical solutions in each specified case. This factcts, (among many other problems) implies energy transmission that is technically, technologically, economically and environmentally aligned with the often difficult to predict dynamic needs of system components and the end user, with acceptable losses -at least in a wide range of possible environments defined by various possible conditions. This paper is the first upgrade of the series dedicated to the symbolic graphic representation of hydraulic system components according to valid technical standards. In this sense, the text presents and functionally describes only some of the much larger set of typical examples of hydraulic energy transmission and associated control functions in modern agricultural technology.

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V Dragan Petrović

Papers

Hydrostatic Transmission Systems of Power and Motion

On the fertilizer particle motion along the vane of a centrifugal spreader disc assuming pure sliding of the particle

Control components of hydrostatic and hydraulic systems: The valves

Hydraulic symbols: Part five: Auxilliary componets

Symbolic representation of hydraulic aggregates and systems