Location Optimization and Force Analysis of Hinge Points of Luffing Push-pull Mechanism Based on Pedal Circle
In order to optimize the location relation between the upper and lower hinge points of the push-pull rod and rotation center of luffing rod in luffing push-pull mechanism, luffing push-pull structure sketch was built. Mechanical analysis found that the pedals of the moment arm of the push-pull rod about the rotation center of luffing rod fell on the same circle which is called pedal circle. Furthermore, one of the diameters of the pedal circle perfectly coincided with the line connecting the rotation center of luffing rod directly to the lower hinge point of push-pull rod. According to the load applied on the luffing rod, driving force and structural dimensions of push-pull rod, the equations were derived for the diameter of pedal circle and the minimum extreme point of relevant parameter was obtained. According to the conditions assumed for extreme point, luffing push-pull mechanism was divided into short, constant and long luffing rod types. Different methods and algorithms have been used to calculate the diameter of pedal circles for different luffing rod types. The force analysis of three hinge joints have also been carried out and Mathcad software was employed for data simulation.