Retaining forces acting on the carriage of a simple cable logging system validated using a static model and a real-world live skyline cable logging system.

<p>We classified three simple cable logging systems using a static model to evaluate the retaining forces exerted on the carriage under load. The three systems differed in the number of boosting forces: single, double, and triple, according to the loading block pulley configuration of the carriage. Retaining forces were almost negligible in the single boosting system; however, they were significant in the double and triple boosting systems under tension, i.e., when the raised logs were located slightly downhill from the carriage. Retaining forces increased with the inclination of the skyline and were smallest in the single boostimg system and highest in the triple boosting system. The difference in retaining forces between the single and double boosting systems was greater than that between the double and triple boosting systems. A real-world test was conducted for a double boosting force arrangement using a live skyline cable logging system. The logging operation used a swing yarder to extract thinned whole-tree logs under partial suspension. Carriage retention forces were confirmed in all eight cycles. Pulling cable line tension forces were observed in the range of 1.4 to 7.3 kN just prior to the movement of the loaded carriage. The skyline tension at the top spar ranged between 9.3 and 20.1 kN, suggesting that the proper arrangement of guy lines would contribute to the efficiency and productivity of the system.</p>