Topological Structure Synthesis of a Novel Multi-mode Parallel Container Spreader Based on POC Sets

Owing to the need of the 'digging container' operation function of the dual 40 feet container spreader, a novel multi-mode switchable container spreader controlled by parallel branches is designed. The container spreader is controlled to adjust the folding posture of the spreader mechanism and auxiliary supported by the contacted profile surface by two parallel branches, and realize the digging operation. Through the analysis of the functional requirements and working conditions of the existing container spreader, the requirements of six independent displacement outputs of the spreader structure are obtained. Then the structure of the mechanism is synthesized based on the topological theory of POC set, and the design of the 6R mechanism with parallel adjusting branches is studied. The completed dual 40 feet container spreader can switch between the single-row operation mode and double-row operation modes, and adjust relative position and posture of the dual spreaders, so as to satisfy the adaptability of the spreader to various working conditions. The design can greatly improve the loading and unloading efficiency of containers.