Study on changes in material properties of air spring rubber bellows for railway vehicles

Because the need of labor-saving in train maintenance continues to increase, it has become essential to evaluate the endurance and long-time applicability of air springs, which are very important components to control train vibration. Endurance tests of air springs revealed that their rubber bellows degraded by oxygen at the initial stage of usage. As stresses are loaded repeatedly, however, molecular chains are partly cut off, and consequently the tensile strength decreases. It is also found that the degradation of air spring rubber bellows is apparently different at different locations and in different directions in the air spring because it is strongly influenced by the vibration mode, for example, the center part of rubber bellows degrades to some extent because it is subject to train vibration, while the upper and lower parts of rubber bellows don't degrade so much because they are isolated from strong vibration.