2020 Volume 55 Issue 3 Pages 362-370
Gantry cranes for container handling (hereinafter referred to as cranes) have experienced unexpected runaways caused by wind. The purpose of this paper is to clarify the effects of wheel load and sliding velocity on the frictional characteristics of the interface between crane wheels and the rails under dry conditions, which serve as a basic information when conducting a dynamic simulation analysis and designing cranes. In our experiment, we adopted an originally developed experimental analysis system and set such characteristics as the pressing load (wheel load) of the wheel on the rail and sliding velocity based on data collected when the crane started to run away by wind. It was found that the static friction coefficient, which is essential for clarifying conditions for a crane that starts to run away, was basically constant irrespective of the scale of the wheel load. In contrast, the dynamic friction coefficient, which is crucial for analyzing the dynamic characteristics of a runaway crane, showed a decrease when the wheel load and the sliding velocity increased. In this paper, we have examined the effects of wheel load and sliding velocity on the dynamic friction coefficient from a viewpoint of plowing and adhesion theories. In addition, we have shown the ratios of the dynamic friction coefficient to the static friction coefficient that can be used as a reference when designing cranes.
