Degradation properties of cone-type axle spring rubber for railway vehicles

To economize on the manpower needed for train maintenance, evaluation of the degradation properties of the cone-type axle spring rubber is strongly demanded. It is a very important material to control train vibration, and whether it can be used for a long period of time must be examined. As a result of experiments on degradation properties of the axle spring rubber, the following properties have been revealed. As the initial stage of its usage, the inner layer of axle spring rubber is degraded more in molecular chains than in the middle and outer layers because the vibration load is applied directly to the soft inner layer. As the inner layer is degraded, however, it loses the ability to absorb vibration, and the vibration load is transferred to the middle layer. Consequently, the degradation is the greatest in the middle layer of the three layers after it is used for several years. Moreover, the degradation of the axle spring rubber can mainly be attributed to complex factors, such as environmental conditions, heat generated when the rubber absorbs vibration energy and fatigue due to vibrating stress.