Design and prototyping of multi-purpose electro-hydraulic steering valve for tractors and self-propelled machines

This thesis focuses on the design, prototype production, and performance evaluation of a high-accuracy, consistent electro-hydraulic steering valve for tractors and self-propelled machinery. Conducted in response to the increasing demand for mechanization and automation in the agricultural sector, the study involved an extensive literature review of existing systems, followed by theoretical calculations and engineering simulations. The valve's components, including proportional solenoids, various spool types, and different springs, were selected based on stroke-force graph comparisons. Structural analyses were carried out using ANSYS Workbench and Simcenter Amesim software, complemented by stroke-flow tests and pressure loss simulations for the ODS valve. The valve's performance was tested in two different environments: an asphalt test track and a field. On the asphalt track, the valve's accuracy and consistency were evaluated, while in the field, its performance was analyzed through integration with an automatic steering system. The findings revealed that the electro-hydraulic steering valve exhibited high accuracy and consistency, with a total deviation of 8.68 mm and an average deviation of 0.13 mm on the asphalt track, and a total deviation of 119.28 mm and an average deviation of 2.29 mm in the field tests. These results indicate that the valve provides an effective automatic steering solution for tractors and self-propelled machinery. Future research is recommended to assess the use of stepper motors instead of proportional solenoids in the valve's control mechanism, to enhance system performance and energy efficiency. This study makes a significant contribution to the development of automatic steering systems in the agricultural and machinery sectors.