Productivity, setup time and costs of a winch-assisted forwarder

Abstract

ABSTRACTIn fully mechanized cut-to-length timber harvesting operations, the forwarder represents the limiting machine on steeper terrain in terms of trafficability. In order to operate also on steep terrain and on soft soils with low traction they can be equipped with traction winches. The objective of this study was to investigate setup time, develop a productivity model and calculate extraction costs for the winch-assisted forwarder John Deere 1110E. The productivity model is based on 75 observed cycles within 18 skid trails. The study was carried out in three different stands using detailed productivity and process analyses. Factors, which influence machine productivity, are piece volume (pv), inclination, distance during loading activities and extraction distance. With an average observed pv of 0.10 m3 and an average load volume of 9.25 m3, the winch-assisted forwarder reached a productivity of 13.7 m3/PSH15, according to the developed model. By an annual utilization of 1,900 h and system costs for the entire machinery of 110.68 €/PSH15, forwarding costs 8.06 €/m3. The detailed time and motion study showed different possibilities for mounting the cable depending on operation direction, terrain, passability through the stand and availability of the harvester. Average setup time for the cable operating downhill was 21.6 min, which additionally caused costs of 1.03 €/m3.