Abstract
The objective of this resarch is to study the optimum method of tower yarder yarding from the standpoint of the lateral yarding. The reserch of the lateral yarding was given by the method of the running sky line on a steep and a downward slope. The relation between the difference work methods, the difference obstacle density and the lateral yarding of the tower yarder yarding were studied. The delay generation frequency during the latelal yarding by the fishbone cutting and full tree logging method showed the smallest value in all methods used. The lateral yarding velocity had a tendency to decrease exponentially with increaseing the obstacle density (the remaining tree density in the neighborhood of the working place). The ordinary yarding had a tendency to decrease more slowly with increasing the obstacles than that of full tree logging, the small effect of obstacles on the lateral yarding time is guessed to be until about r = 0.1 of obstacle density.
