COIL SPRING FOR TORQUE REDUCTION IN TRACTOR FOLDABLE ROPS

ABSTRACT Studies conducted by the international labor organization have shown that operations involving agricultural machinery are among the three activities with the highest risk of accidents to workers. Among the possible causes, rollover is the most common, accounting for 33% of fatal accidents. Despite this, there are standards that provide for the use of safety devices to ensure the physical integrity of the operator, among these equipment stand out rollover protection structures, which can be foldable or not. In this sense, the objective of this study was to perform an ergonomic study in order to analyze the torque required for lowering and lifting a foldable rollover protection structure attached to an agricultural tractor, developing instrumentation for validation of the efforts required to operate the structure and comparing the results obtained with the values recommended by the Standard (CODE 6 - OECD). When torque values were above those recommended by the standard, a set of torsion springs was used as solution to torque reduction. After further testing, the effectiveness of the solution was verified. Furthermore, it was observed that the angular speed of the bar does not have a significant influence on the torque required to lift the bar.

摘要 国际劳工组织（International Labor Organization）开展的研究显示，涉及农业机械的作业是对劳动者而言事故风险最高的三类活动之一。在各类事故诱因中，翻覆最为常见，占致命事故总量的33%。尽管如此，现有安全标准均规定需配备安全装置以保障操作人员的人身安全，其中防翻覆保护结构（rollover protection structures）尤为关键，此类结构可分为可折叠式与固定式两类。据此，本研究旨在开展人机工效学研究，以分析安装于农用拖拉机的可折叠式防翻覆保护结构在升降过程中所需的扭矩；同时研发用于验证该结构操作所需受力的测试装置，并将实测结果与标准（CODE 6 - 经济合作与发展组织（OECD））推荐的数值进行对比。当实测扭矩值超出标准推荐阈值时，研究采用一组扭转弹簧作为扭矩优化方案。后续测试验证了该方案的有效性。此外，研究还发现，支撑杆的角速度对升降该结构所需的扭矩无显著影响。