Research on the overload protection system of knuckle boom crane

Abstract

Due to the particularity of the knuckle boom truck-mounted crane structure, it is difficult to express the rated operating capacity at various states simply with the rated lifting load curve. The operator cannot get an intuitive understanding of the operational capacity of the crane. Therefore, there is a big security risk. According to the GB 6067–2010 “Safety rules for lifting appliances,” the overload protection system must be installed on the knuckle boom crane. In this paper, studying on the structural characteristics of the knuckle boom crane, a torque limit method is proposed based on programmable controller, weight sensor, angle sensors, length sensor, and electromagnetic unloading valves. And it is introduced from the system structure, establishment of a mathematical model, and so on. The overload protection system based on this method is now applied to a knuckle boom crane, and the method can dynamically and accurately reflect the rated lifting load, lifting load, and operating range and also achieve the crane overload warning and action limits in any conditions, providing a guarantee for safe operation, and the system can also be programmed to expand vertical lifting function, with a very good application prospect.