The high mobility of open pit machines in heavy duty conditions provides fertile ground for the occurrence of various failures of the traveling mechanisms’ vital parts such as chain links. The goal of the study presented in this paper was to diagnose the cause of the damage of the bucket wheel excavator crawler chain links. In order to identify the reasons behind chain link failures, stress state calculations were performed as well as experimental investigations which, given the nature of the failure, included visual and metallographic examinations, chemical composition analysis and tests of mechanical properties. Based on the results of the numerical-experimental analyses, it was concluded that the chain link breakdowns are caused by ‘manufacturing-in’ defects. The results of the presented analyses also emphasize the importance of a comprehensive quality control of chain links.http://www.sciencedirect.com/science/article/pii/S1350630713001611