The four-line model of the Triangular Running Skyline system: Theory and numerical examples

The generalized static solution of the Triangular Running Skyline (TRS) system has been derived. A pair of tail spars with a haulback line enables the carriage of the TRS system to move around over the triangular area formed by connecting the bases of the three spars with each other,i.e., the two tail spars and one head spar. From the head spar, the main and slack-pulling lines stretch toward the carriage to move up and down the load. The theory derived in this paper separately evaluates the line lengths and line tensions of the main and slack-pulling lines (the four-line model), while the previous theory treats these two lines as a single equivalent line (the three-line model). Four numerical examples provided in this paper ascertained the accuracy of the two procedures of the four-line model. A part of this paper was orally presented at the Second Annual Meeting of the Japanese Forest Engineering Association, November 18, 1995, Tokyo. This English title is a tentative translation form the original Japanese by the authors of this paper.