Abstract
This study aimed to develop a thinning system using an excavator with long-reach grapple for prehauling operations. We examined the effects of thinning method, prehauling direction, terrain and road condition on productivity. The maximum productivity of labor was 9.0m3/man-hour under the conditions of line thinning, down-hill prehauling, slope of 23°, short prehauling distance of up to 33m, road width of 3.5m and timber volume of 0.32m3/tree, which was about 1.5 times higher than ordinary thinning at 5.9m3/man-hour under similar conditions. Using a small winch on the top of the arm, the maximum slope prehauling distance from thinning trees to roads exceeded 70m, and the productivity decreased only 10%. The productivity for downhill prehauling was about 1.6 times higher than for uphill, and the maximum prehauling distance for downhill was 6m longer than for uphill. The productivity for the road width of 3.5m was about 1.6 times higher than for 3.0m. On the other hand, the terrain had little effect on productivity. Consequently, this machine offers high productivity for both ordinary and line thinning, although a road structure that can support the heavy weight of this machine is needed.
