In recent years, there has been an increase in the volume of 40-ft marine high-cube containers handled in logistics in Japan. In Japan, the height of 40-ft marine high-cube containers limits the number of sections where they can be transported by rail. To solve this problem, it is necessary to develop a new freight car with a cargo bed height of 700 mm, which is 300 mm lower than a conventional freight car (bed height: 1000 mm) currently in use. For this purpose, a new carbon fiber reinforced plastic (CFRP) model secondary suspension spring with a lowered spring height has been developed to expand the possibilities of lowered bed height. Previous research has shown that the proposed CFRP spring is effective as a space- saving spring and it has nonlinear spring characteristics. Tests were conducted using different materials and shapes for the components of the spring. This paper shows the factors that change the nonlinear characteristics of the proposed CFRP spring.
