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A. P. B. Krpan, T. PorSinsky: DJELOTVORNOST STROJNE SJEČE I IZRADE U SASTOJINAMA Šumarski list br. 5 6. CXXV1M (2004), 233-244 P u l k k i , R., 2001: Cut-to-length, tree-length or full Staff, K. A. G., N. A. W i k s t e n , 1984: Tree harvesttree harvesting, http://flash.lakeheadu.ca/ ~re- ing Techniques. Martinus Nijhoff/DR W. Junk pulkki/ctlft.html Publishers, Dodrechts/Boston/Lancaster, pp. 371. R i c h a r d s o n , R., I. M a k k o n e n , 1994: The perfor- Tufts, R. A., 1997: Productivity and cost of the Ponsmance of cut-to-length systems in eastern Cana- se 15-series, cut-to-lenght harvesting system in da. For. Eng. Res. Inst. Can. (FERIC), Pointe- southern pine plantations. Forest Products Jour- Claire, Que. Tech. Rep. TR-109. 1-16. nal 47 (10): 39^46. S e r d a r , V., I. Š o š i ć , 1981: Uvod u statistiku. Školska knjiga Zagreb, 1-452. SUMMARY: This paper shows the results of research of machine felling and processing carried out by Timberjack 127 0B Harvester in a 23-year old willow culture. The volume of the mean felling tree was 0.5 m3, and diameter at breast height 25 cm. The felling density was 633 trees/ha. Thick undergrowth layer is made of bird cherry, black elder, common dogwood and glossy buckthorn. The harvester s operation was monitored for 6 working days (54.11 h), and during that time 1825 trees were felled and 949.1 m3 of roundwood was processed. The mean diameter of technical roundwood is 29 cm, the length is 4.5 m and the volume 0.30 m . The mean diameter of pulpwood is 17 cm, the mean length is 4 m and the mean volume 0.11 m3. The computer system Timberjack 3000 was calibrated before the operation started. The preset minimum sizes were entered (diameter at the thinner end with bark and length) of first class saw logs (27 cm, 2.5 m), second class saw logs (22 cm, 2.5 m) and pulpwood (7 cm, 4 m). The results confirmed that the dimensions of the processed assortments do not vary from the preset values. Delay times of 52.7 % and effective time of 47.3 % of the total recorded time were established by time study. With such a time ratio, the harvester achieved an efficiency of 17.5 m3/h or 34 trees/h, consuming a total of 3.42 min/m3. The average consumption of effective time is 1.62 min/m3. Felling and processing account for 66.1 %, hydraulic crane idling for 17.8%, undergrowth cleaning for 12.8 %, and harvester moving at the felling site for 3.3% of effective time. Allowance time was 30.9 %> of effective time. The values of standard time and harvester productivity have been investigated by regression analysis and fitted by exponential curve with a very strong correlation. In doing so, it has been established that 84 %> of productivity and standard time variability can be explained by the influence of the trees diameter at breast height. Key words: machine felling, Timberjack 127 0B, clear cut of willowculture, efficiency 244 |