Solution approach:

Initial concept studies were carried out by us. A mere variation of the Shore hardness resulted in the radial stiffness of the spring being too high for the motor bogie. Based on this result, and after the customer specification for the vertical charakteristic of the hourglass spring had also changed in the meantime, a new design of the spring's inner contour was developed. For the prototype of the design variant with modified inner contour (rubber contour), the required service life verifications for the elastomer, as well as the strength verification of the metal parts (FKM guideline) were then provided for the specified load cases.

Results:

A new design for the secondary suspension of the motor bogies was developed for our customer. All required service life and strength verifications for the specified fatigue load cases were provided.