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Sirvi Autor "Liivapuu, Olga" järgi

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  • Pisipilt
    Kirje
    A justification of the choice of parameters for the picking reel tooth on a lowbush blueberry harvester
    (2021) Arak, Margus; Liivapuu, Olga; Maksarov, V.V.; Olt, Jüri; Estonian University of Life Sciences. Institute of Technology
    The functional working tool on the blueberry harvester is its rotating picking reel. Its working element is the picking rake which is attached to the picking reel. A total of four rakes are attached to the picking reel. A picking rake includes an axis which is attached in an articulated manner between the reel’s end discs, and pin-shaped teeth which are rigidly attached to it. The picking rake’s tooth must be made of a fully flexible material to prevent damage to the blueberry plant. The aim of this research was to determine the flexure of test specimens (plastic rods) which have been constructed from a fully flexible material of different conditions, along with the suitability for use of such flexible material as the teeth on the picking rake. As a result of this study, it became clear that, based on the results from flexure, durability, and residual deformation tests, it is more expedient to choose Ertacetal C (POM-C) as the material for the picking reel’s tooth, with a diameter of 4.3 mm.
  • Pisipilt
    Kirje
    Theoretical study of the movement of the wide span machine in quasi-static turning mode
    (Estonian University of Life Sciences, 2024) Olt, Jüri; Bulgakov, V.; Adamchuk, V.; Kuvachov, V.; Liivapuu, Olga; Estonian University of Life Sciences. Institute of Forestry and Engineering
    Wide span machines represent sophisticated energy and technological tools for controlled traffic farming. The curvilinear movement (turning) of these machines are often decisive in the design of new or evaluation of existing models of equipment. The application of classical theory of turning in researching wide span machines faces certain challenges due to limitations imposed when describing the force or kinematic interaction of their movers with the supporting surface along a constant technological track. Additionally, non-traditional control schemes further complicate the use of the classical turning theory. The present research aims to study the curvilinear motion of wide span vehicles in a quasi-static turning mode, allowing for the modelling of their turns with combined or non-traditional movers under various control schemes. As a result of the conducted research, it was established that a promising non-traditional turning scheme for a wide span machine is one where one rear wheel is driving, and the other is braking, with controllable front wheels. In this case, the turning radius of the machine is 1.5 times smaller compared to traditional turning schemes. It was experimentally proven that the practical implementation of this new non-traditional turning scheme for the wide span machine is limited by the magnitude of the load on its front wheels relative to the rear ones.