Effect of log length on productivity and cost of Timberjack 450C skidder in the Hyrcanian forest in Iran

This paper presents research results on the performance of the Timberjack 450C skidder in timber skidding at two working sites of broadleaved trees in mountainous conditions in the Hyrcanian forest. To evaluate the current skidding system in the Hyrcanian forest in northern Iran and possibility of finding out better techniques and group organization an empirical time study has been conducted. The elements of the skidding work phase were identified and 123 cycles were recorded for short-log and long-log method. The models for effective time consumption, total productivity and unit cost of skidding in short-log and long-log method were calculated. The time consumption and productivity of skidding depend on several variables such as distances and slope, number of logs per cycle and volume. The average load per cycle in short-log and long-log method was 2.77 m3 and 3.08 m3, the average one-way skidding distance was 380 and 497 m, the average slope was 18 and 20% in the short-log and long-log method, respectively. The average travel speeds of unloaded skidder were 5.74 km.h-1 and the average speeds of loaded skidder were 7.67 and 6.16 km.h-1 in short-log and long-log method, respectively. The average speeds of pulling the cable were 1.71 km.h-1, and of load winching 0.72 km.h-1 and 0.69 km.h-1. The average outputs in short-log and long-log method were 10.86, 11.11 m3.effective h-1. Results indicated that hourly costs of operation were higher for the short-log method than for the long-log method (12.69 vs.12.40 USD.m-3).