Jacques Malchaire

Technical characteristics of overhead cranes influencing the vibration exposure of the operators.

The study was undertaken to determine the technical factors responsible for the generation of vibration and shocks in overhead cranes and therefore responsible for complaints by the workers. Vibration measurements were made on the floor and on the seat of the cabin on 21 cranes. Vibration levels were correlated with the characteristics of the cranes. The study showed that vibration accelerations increased with the span of the crane and were very dependent upon the state of the runway. The type of speed regulation and the position of the cabin also play a significant role. The suspension systems of the cabin and the seat are clearly inadequate to give significant reduction of the vibration. In several cases, it was even shown to amplify the vibration in the most critical frequency range. These results should be taken into account by designers as well as maintenance services in order to prevent the development of vibration at the source.