Abstract
A set of 2.2 m diameter, cast steel pulleys, fabricated in the year 1949 with a plain carbon ferritic-pearlitic steel and used to drive the haulage ropes of a mountain cable transportation system, were examined to assess whether some of them could still be safely employed. Each pulley was used to perform a total estimated number of cycles (revolutions) ranging from 4 to 100 million (for pulleys serving different tracks), some of them being employed for almost 60 years. Several casting cracks spanning the surface for up to 50 mm were found by magnetoscopic analyses, and one of them, more than 25 mm deep, was investigated in detail by cutting one pulley. Fractographic examinations provided evidences of fatigue crack growth; however, such a phenomenon was very limited in respect to the original crack size, thanks to very low design stresses. Operational safety is discussed on the basis of FE analysis.