Investigation of Cargo Suspension Oscillations of the Timber-Hauling Aerial Logging System
One of the main factors constraining the increase in logging volumes in the Far Eastern Federal District in the steep terrain is the complexity of the technological process for primary wood transportation from the point of harvesting to the place of storage and loading. About 30 % of forest areas with a high quality and mature forest stand are located on slopes with the ratio over 20˚, where traditional technology is either unable to harvest timber, or performs it with high costs and with clear ecological disturbance. The experience of the use of balloon systems of timber transportation has proved their technological and silvicultural efficiency. However, the method of selective removal of separately growing trees requires additional and comprehensive research, since it is associated with the structural and technological features of balloon systems, primarily with the functioning of a cargo suspension with a gripping mechanism. The paper presents the results of practical and theoretical studies of the oscillation process occurring in the cargo suspension of a trilinear aerial skidding system designed for vertical harvesting of trees with their subsequent transportation. A mathematical model describing the equilibrium of the point of joining of the aerial skidding system and its movement under arbitrary loads is developed. The dependence obtained allows determining the vibration parameters of three interconnected points of the system cargo suspension under various operating conditions and at any given time. The calculated values of parameters of the oscillating process of the cargo suspension and the deviations of the load gripping mechanism from the point of tree getting, allow undertaking the design of technical parameters of load gripping and winch mechanisms intended for the air transportation of timber very accurately. On the basis of the obtained results, technological and constructive features of aerial skidding systems can be used in selective logging more efficiently.