SIMULATION-BASED VALIDATION OF NEW CONCEPTUAL CABLE HARVESTING SYSTEMS

Forest harvesting on the ground with a harvester or harwarder made a significant stride in the productivity while cable harvesting systems used on steep slopes have not greatly changed since the combined yarder/processor was developed. In this study, we proposed a cable harvesting system using an independent device for lateral yarding, which was expected to improve the productivity with less intensive investment. Then, we estimated the productivities when an independent device for lateral yarding was introduced to the conventional gravity system and gondola cable system. As a result, the productivities of both of the new cable harvesting systems were better than that of the conventional gravity system for all distances (20-300m). However, the effect of the independent device for lateral yarding was limited when logs were yarded for relatively short distances (20-100m). The gondola cable system had the great advantage in the productivity when the yarding distance was 120-300m. On the other hand, the total yarding time of the conventional gravity system increased in proportion to the yarding distance. In conclusion, both of the new cable harvesting systems had the advantage in the productivity over the conventional gravity system when the yarding distance was 120m or more.