Modelling and dynamic analysis of an integrated hydraulic forest crane-winch system for timber extraction

This paper details the dynamic modelling and analysis of an integrated hydraulic forest crane-winch system used for timber extraction, concentrating on transient behaviour during winch activation from rest. A comprehensive mathematical model was developed to capture the coupled dynamics of the winch drum rotation, the crane boom, and the suspended timber log, using the Lagrangian formulation. The resulting system of coupled, nonlinear second-order ordinary differential equations was solved numerically using custom algorithms. Dynamic analysis revealed transient overloading: peak drive torque, rope tension, and boom elastic force exceeded steady-state values by factors of 4.47, 2.44, and 2.91, respectively. High-frequency damped oscillations superimposed on low-frequency payload sway were identified, attributed to the abrupt drive torque application. This research highlights the necessity of dynamic analysis for predicting significant stress amplification in such systems and provides a framework for characterising transient loads, indicating smoother start-up strategies are essential for improving system reliability and efficiency.