20.500.12556/RUL-114225 Proizvodnost traktora Ecotrac 120V pri privlačenju drva u brdskom području središnje Hrvatske Productivity of tractor Ecotrac 120V timber skidding in hilly area of Central Croatia U radu su prikazani rezultati istraživanja proizvodnosti rada skidera Ecotrac 120V na privlačenju drva poludeblovnom metodom iz proredne i dovršne sječine. Terensko je istraživanje provedeno studijem rada i vremena. Razlike u obujmu tovara, brzini vožnji, izvlačenju užeta i privitlavanju te razlike u utrošku vremena pojedinih radnih zahvata na sječini i rada na pomoćnom stovarištu istražene su t-testom. Za radne zahvate za koje je utvrđena značajna razlika između promatranih sječina u daljnjim su izračunima primijenjene individualne prosječne vrijednosti za pojedinu sječinu, dok su kod ostalih radnih zahvata izračunate nove, zajedničke prosječne vrijednosti. Utrošci vremena vožnji izračunati su na temelju prosječne brzine i udaljenosti privlačenja. Utvrđena je značajna razlika između obujma tovara iz proredne i dovršne sječine. Razlike su u utrošku vremena najočitije u skupini radnih zahvata na sječini, a nastaju kao posljedica različite udaljenosti izvlačenja užeta i privitlavanja tovara. Projektirani dnevni učinak u dovršnom je sijeku prosječno 21 % veći nego u prorednoj sječi uz prosječno 26 % niže jedinične troškove. Detaljnom analizom utrošaka vremena pojedinih radnih zahvata utvrđeno je da na razliku u proizvodnosti i troškovima bitan utjecaj imaju sječna gustoća sastojine i prosječan obujam posječenoga stabla. Različita sječna gustoća utječe na različit utrošak vremena rada na sječini i posljedično na ostvarivi dnevni učinak. Na proizvodnost rada skidera uz sječnu gustoću još veći utjecaj ima prosječni obujam posječenoga stabla jer omogućuje formiranje tovara zadovoljavajućega obujma na kratkoj udaljenosti privitlavanja vezivanjem manjega broja komada, često uz upotrebu samo jednoga bubnja vitla. Stoga se može zaključiti da mogućnost postizanja najvećih učinaka u zadanim sastojinskim i eksploatacijskim uvjetima leži u optimalnom odnosu između veličine tovara i vremena utrošenoga pri radu na sječini koje je nužno za njegovo formiranje. This paper presents the research results of skidder Ecotrac 120V productivity in thinning and final felling half-length wood skidding. Terrain research was conducted using time and motion study at two worksites. Worksite A is a mixed stand of beech (48.74%), sessile oak (4.47%), hornbeam (21.06%) and linden (15.65%), aged 57 years, in which thinning was done. Harvesting density was 34.07 m$^3$/ha, and mean cutting tree was 0.63 m$^3$. At the worksite B, in the beech (92.03%) stand, aged 111 years, final felling was conducted. Harvesting density was 89.50 m$^3$/ha, and mean cutting tree was 3.51 m$^3$. Based on the data collected, the structure of the total time consumption and average daily output was calculated (Table 1). The analysis of recorded delays provided allowance time (Table 2). Differences between load volumes, travel speeds, line pulling and winching speeds and time consumption of individual felling site and landing work elements were investigated by a t-test (Table 3 and Table 4). For those work elements that showed significant differences between worksites, individual mean values were used for further calculations, while for the others, new common mean values were calculated. Travel time consumption was calculated based on the average speed and pertaining skidding distance. A significant difference (t = -3.571562; p = 0.000519) was found between load volumes of thinning (3.050 m$^3$) and final felling site (3.717 m$^3$). Differences in time consumption (Table 4 and Table 5) are the most obvious in the group of felling site work elements, and they are a consequence of different line pulling/winching distances needed for forming the achieved load volumes. The projected daily output (Fig. 2) of final felling skidding is in average 21% higher than in the thinning skidding with an average 26% lower costs per unit (Fig. 3). Detail analysis of each work element time consumption showed that harvesting density and mean cutting tree volume have an important impact on difference in productivity and costs. Different harvesting densities affect the felling site work time consumption, thus also affecting the achievable productivity. Besides the above mentioned harvesting density, mean cutting tree volume has an even greater influence on skidding productivity because it enables the formation of preferred load volume at short winching distances by choking fewer half-stems, often with the use of just one winch drum. Therefore, it can be concluded that the possibility of achieving greatest outputs, in given stand and harvesting conditions, lies in the optimal relation between the load size and the felling site work time consumption needed for its forming. proizvodnost troškovi sječna gustoća prosječni obujam posječenoga stabla proreda dovršni sijek productivity costs harvesting density mean cutting tree thinning final felling true false true Hrvaški jezik Angleški jezik Članek v reviji 2020-02-19 13:57:08 2020-02-19 13:57:09 2025-05-14 16:34:16 0000-00-00 00:00:00 2019 0 0 KLJUČNE BESEDE: proizvodnost, stroški, gostota sečnje, povprečni premer odkazanega drevesa, redčenje Str. 1–10 Vol. 40 2019 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 630*3 1845-8815 10.5552/nms.2019.1 5630118 1715366 1.pdf 1.pdf 1 E04F0D386CEBE67C688C346BB60C1FEE 526b1236f851fd76b13cc9064a5d4f99949443d7f2e5bab30f84946b244d84e4 e814e371-1466-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=201458 http://www.jnms.eu/zecic-i-dr/ 0 e1eae99f-1466-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=201457 Biotehniška fakulteta 0 0 0