Bridge Cranes Wheels and Rails: Wear Analysis

1 Abstract The wear phenomenon is one of the more critical aspects for wheels and rails of bridge cranes and it is mainly caused by rails alignment and levelling irregularities. These irregularities are related to the respect of functional tolerances, which are very difficult to keep due to the building dimensions and precision. The supporting walls are in fact a hundred meters long and are affected by severe geometrical errors. In order to reduce the wheel/rail wear overhead cranes manufacturers test new materials which can be used to reduce the wear phenomenon. The wear behaviour of these materials cannot be evaluated directly on bridge cranes since should be necessary to equip the system with sensors in order to acquire data on the crane while operating. Furthermore the wheel and rail profiles have to be measured several times during tests, requiring the crane to stop operating. For this reason it is necessary to dispose of specialized test rigs able to evaluate the wheel and rail wear under specific conditions. The paper describes the tests performed on different types of wheel and rail materials, commonly used for the manufacture of bridge cranes wheels and rails. The tests have been performed on the roller-rig which allows the tests to be performed considering different operating conditions in terms of normal load, creep and reference velocity. The results are analysed and used to evaluate the Archard's coefficients of the materials analysed.