Study of the Kinematics of the Positioning Mechanisms of Wide-Grip Machine-Tractor Units

Abstract

As stated in the humanitarian food program "Grain from Ukraine", launched by the President of Ukraine Volodymyr Zelenskyi: "The demand for agricultural products in the world is growing by 2-3% every year, and the shortage of grain on the markets of Africa and Asia may reach 10-15% already in 2024". Therefore, the issue of production of agricultural products is relevant today. As the analysis of the market of agricultural machinery shows, one of the directions of the development of the design of agricultural units is to increase the width of grip of tools for soil cultivation and plant care. The use of agricultural units with an increased working width has certain advantages: - reduction of the number of passes of equipment on the ground; - reduction of fuel consumption; - reducing the negative impact of the unit on soil density. Among the disadvantages of this type of aggregates should be attributed the increase in turning radii, as a result of the increase in width. It is possible to eliminate this shortcoming by quickly transferring the unit from the working position to the transport position and vice versa. To fulfill this task, a review of known designs of wide-grip aggregates was carried out. Known hydraulic drives for raising and lowering and folding and unfolding sections are considered. A kinematic diagram of the mechanism of rotation of the extreme section of the cultivator relative to the frame has been developed. Based on this calculation scheme, the reactions in the hinges were determined and the graphical dependencies of the mutual location of individual elements with respect to the angle of rotation φ were calculated. The existing hydraulic positioning mechanisms, which are equipped with chainless wide-grip machines and tools with articulated frames, do not provide the necessary maneuvering properties of MTA during their movement on the turning lane. Equipping hydroficated positioning mechanisms with follower stabilizing devices is a promising direction for improving hydraulic drives of machine-tractor units, which create prerequisites for reducing the turnaround time on the turning lane by selecting the parameters of the specified equipment. The most important factor affecting the stability of the positioning of the sections of wide-grip machine-tractor units is the variable load that occurs on the hydraulic cylinder rod at the moment of turning the sections around the horizontal hinges at an angle of more than 90⸰, which causes inconsistency in the flows of the working fluid entering and leaving the hydraulic cylinder , which leads to the interruption of the flow in the cavity of the hydraulic cylinder, which is connected to the injection hydraulic line.