Mathematical Description of the Loads on a Timber Loader Crane during Dynamic Slewing Motions

Abstract

The requirements for load capacity, reach, and handling performance of timber loader cranes are continuously increasing, while the permissible gross vehicle mass remains limited. To meet these requirements, an accurate description of the loads occurring during operation is of great importance. If these loads are subject to large uncertainties, the crane structure must be designed more conservatively. Therefore, this work investigated the accuracy of the calculation approach specified in EN 12999 for dynamic slewing motions. Using a validated multibody system (MBS) model, the dynamic loads occurring at the crane tip were analyzed. The results show that the standard-based approach does not represent the loads during the investigated slewing motions with sufficient accuracy. The largest deviations occur for the force component acting in the horizontal plane tangentially to the circular path of the crane tip. Without consideration of additional dynamic factors, the standard-based calculation approach deviates from the MBS results by -80 to -85 %. Therefore, an alternative quasi-static calculation approach was formulated for this force component, which reduces the deviations to between -21 % and +8 %.