11. GIS-based model of wood precurement from stump to small sawmills in the Alpine region - a case studyJanez Krč, Boštjan Košir, 2009, original scientific article Abstract: With wood logistics and forest operation modelling, we have connected a technologic chain of cutting, skidding and road wood transport operations. The goal of the paper is to present the possibilities of simulating forest operation activities including cost flow prediction. The case study regarding wood flow and forest operation cost modelling was conducted in four municipalities located in western Slovenia (bordering to Italy). Input data of forest inventory and basic forest data were used in order to predict the wood flow in the test area. We modelled the available cutting volumes with the capacities of local sinks - notably sawmills. Unbalanced hinterland areas of specific sinks that do not cover the local sink capacities were changed (reduced or enlarged) on account of the adjacent hinterland areas with surplus or shortage of wood volume. The hauling distances and wood volumes for covering the sawmillsć capacities of the adopted (balanced) hinterland areas were studied.
Published in DiRROS: 12.07.2017; Views: 3656; Downloads: 1722
 Full text (2,54 MB) |
12. Assessing maximum loads when skidding wood uphill with tractorsBoštjan Košir, Jurij Marenče, 2008, original scientific article Abstract: The results of measuring maximum loads on different slopes when skidding uphill with WOO DY 110 cable skidder and adapted 4WD agricultural tractor AGT 835 are described in the article. Both tractors are very different and were chosen for the purpose of finding the limits of uphill skidding. Besides the slope, the pre-designated loads of different sizes and log orientation (butt-end or top-end forward) have been main variables. The trial was conducted on two concave shaped test skid trails in the forest. On the lower altitudes, the skid trails had small inclination, which slowly increased to 42% on the track where WOODY 110 was tested, and 27% where AGT 835 was measured. First the loads were skidded uphill with butt-end and then with top-end forward. The purpose was to choose too heavy loads, as we wished to stop tractors due to overload, but on different slopes. The proper load formation (butt-end forward if possible) in uphill skidding is most important on steeper skid trails. The dependency between maximum load and slope is linear. The calculated theoretical maximum load on horizontal surface enables us to make similar assessment for any other tractor weighing between 2 and 7 tons. For this purpose, John Deere 6220 and LIMB 80 LUXS adapted agricultural tractors for forest use were chosen and compared. The ratio between the tractor load on different slopes and tractor weight was calculated for all four tractors included in our comparison. Apart from the weight, tractor's engine torque (power) has the decisive influence on the load size. Maximum loads on different slope categories were calculated according to different engine powers.
Keywords: tractor, skidding wood, maximum slope, maximum load
Published in DiRROS: 12.07.2017; Views: 4266; Downloads: 1799
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13. Technical parameters dynamics of WOODY 110 cable skidder within the range of stopping due to overload in uphill wood skiddingJurij Marenče, Boštjan Košir, 2008, original scientific article Abstract: The article deals with uphill wood skidding with WOODY 110 skidder and the changes taking place in technical parameters: slip, torque, tractive forces, and weight distribution of a loaded tractor in the last three meters of skidding, which is defined as a range of stopping due to overload. The test was performed on a concave skid trail, where tractor loaded with 8 meter long fir logs stopped at the 32% incline. It stopped somewhat later when skidding with butt-end forward in comparison to skidding with top-end forward. The loadweight with butt-end forward was 31.69 kN, whereas with top-end forward itweighed 33.53 kN. The measured speeds showed minute changes until the last meter, but decreased swiftly after stopping. Regarding some technical parameters, there were almost no changes at the end of stopping, two exceptions being the slip, which increased in the range of stopping, and the forward torque, which decreased in this range. The results showed that the hydrostatic transmission was efficient, considering that in a relatively well-controlled slip (the slip values increase only in the last three meters, which approximately equals the half of tractor's length) there was less grounddamage.
Published in DiRROS: 12.07.2017; Views: 4121; Downloads: 1817
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14. Measuring the limits of uphill timber skidding with a WOODY 110 forestry tractorBoštjan Košir, Jurij Marenče, 2007, short scientific article Abstract: The paper deals with the test results of uphill skidding of wood with a WOODY 110 cable skidder. The aim of the study was to find the limits of uphill skidding in relation to load size, log orientation and the slope. The trial was prepared on a test track of concave shape in the forest and with pre-designed loads of different sizes. The loads were skidded uphill once withbutt-end and then with top-end forward, until the tractor stopped because of the slope. The results show that butt-end forward skidding is more efficient. The difference between maximum loads at specific maximum slopes is almost constant (0.53 t). Proper load formation (butt-end forward if possible)is more important when skidding on steeper slopes.
Keywords: forestry, tractor, skiiding, maximum slope, maximum load
Published in DiRROS: 12.07.2017; Views: 4214; Downloads: 1920
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15. Primerjava metod kalkulacij stroškov gozdarske mehanizacije na primeru žičniceJaka Klun, Boštjan Košir, Janez Krč, Mirko Medved, 2007, review article Abstract: Primerjali smo rezultate kalkulacij neposrednih materialnih stroškov po sedmihuveljavljenih kalkulacijskih metodah za gozdarsko strojno delo. Metode imajo skupno izhodišče pri strukturiranju kalkulacijskih postavk, a se razlikujejo v načinu izračunavanja in upoštevanju posameznih postavk. Primerjava ob predpostavki enakih vhodnih podatkov in upoštevanju letne izkoriščenosti na primeru gozdarske žičnice kaže na razlike v ceni strojnega dela in s tem na težjo primerljivost gospodarnosti stroja na enoto proizvoda. Vhodne podatke za primerjavo metod kalkulacij stroškov dela smo pridobili s spremljanjem koledarskega časa treh strojev, z meritvami pri časovnih študijahin spremljanju učinkov. Pri 1000 obratovalnih urah stroja na leto se po primerjanih kalkulacijskih metodah lahko materialni strošek na enoto spravila razlikuje za več kot 50 %. Največje razlike nastajajo predvsem zaradirazličnih pristopov pri obravnavi variabilnih stroškov. Potrebna je previdnost pri interpretiranju kriterijev gospodarnosti, zlasti pri konkuriranju na enotnem trgu dela in storitev.
Keywords: kalkulacija stroškov, gozdarski stroji, žičnice
Published in DiRROS: 12.07.2017; Views: 4162; Downloads: 1839
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16. Wheelslip in skidding with the AGT 835 T adapted farm tractorJurij Marenče, Boštjan Košir, 2007, original scientific article Abstract: The paper presents a wheelslip measurement method for small farm tractors (AGT835 T) adapted for skidding, with mechanical and hydrostatic mechanical transmissions. The research focused on uphill skidding, as slip values measured in uphill skidding are higher than in downhill skidding. A comparisonwas made of the performance of tractors carrying equal load but equipped with mechanical and hydrostatic transmission systems. The hydrostaticdrive causes higher negative load values in downhill skidding, and slightly higher slippage. As for hydrostatic tractors, wheelslip is higher in uphill skidding than in downhill skidding. The increase in the sloping of the terrain causes wheelslip to rise progressively. When a tractor travels uphill,slip is linked to a loss of energy. Wheelslip measurements are therefore important for determining the optimum conditions for individual tractor types.
Keywords: skidding, farm tractor, wheelslip, measurement
Published in DiRROS: 12.07.2017; Views: 4340; Downloads: 1916
Full text (722,66 KB) |
17. Statistično spremljanje razvoja mehaniziranosti gospodarskih družb v obdobju od leta 1966 do leta 2002Simon Resman, Boštjan Košir, Mirko Medved, 2005, original scientific article Abstract: Analizirano je statistično spremljanje opremljenosti gospodarskih družb za delo v gozdni proizvodnji. Razvoj spremljanja družb je glede na posamezne objave razdeljen v tri obdobja: 1966-1985, 1986-1992 in obdobje po letu 1994. Zbrani so nekateri pomembnejši podatki za obdobje od leta 1966 do 2002, ki kažejo na razvitost gozdarske stroke. Preučeni so podatki o gozdnatosti in količini poseka, številu zaposlenih, opremljenosti in učinkovitosti mehanizacije, o porabi goriva za delo v gozdu ter o graditvi gozdnih cest. Stanje na področju mehaniziranosti gozdarskih podjetij se izboljšuje, a močno zaostaja za opremljenostjo in učinkovitostjo razvitejših držav. Statistični urad RS po letu 1994 zagotavlja redno letno spremljanje podatkov. Da bi bili podatki točnejši, je treba natančneje definirati zahtevane podatke in dosledneje zahtevati vračanje izpolnjenih anket. Neizpolnjen vprašalnik velikega podjetja pomeni precejšnjo vrzel v skupnih analizah podatkov. Ker primerjave med anketiranci zaradi zakona o varovanju podatkov niso več mogoče,je interes za raziskave s strani podjetij majhen.
Keywords: pridobivanje lesa, tehnična opremljenost, gozdarska podjetja, statistični podatki, Slovenija
Published in DiRROS: 12.07.2017; Views: 4155; Downloads: 1817
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18. Koledarski čas in učinki dela z žičnimi napravami syncrofalke na TolminskemMirko Medved, Nikica Ogris, Jaka Klun, Boštjan Košir, Rafael Vončina, 2005, original scientific article Abstract: Prispevek predstavlja analizo koledarskega asa in delovnih uinkov dveh žinic Syncrofalke na Tolminskem. Koledarski as je obravnavan po mednarodni metodologiji IUFRO. Delimo ga na koledarski as delovnega mesta, to je 261 dni,in na koledarski as zunaj delovnega mesta, ki znaša 104 dni letno. Za vsakdan upoštevamo 8 ur, kar velja tudi v slovenski delovni zakonodaji, zato znaša koledarski asi delovnega mesta 2.088 ur letno. Koledarski as je bil spremljan od zaetka julija 2002 do konca marca 2004, skupaj za dve opazovani žinici 1.270 koledarskih dni. V tem asu sta žinici na 79 linijah obratovali skupaj 709 dni, povpreno 204 dni na leto na žinico. Produktivni delovni as, kamor se šteje le spravilo, je znašal v povpreju 132 dni. Povprena dolžina linije, ki je od stolpa do zadnjega škripca v povpreju merila 336 m, je imela 0,62 vmesne podpore na linijo. Povprena razdalja spravila po nosilni vrvi je 208 m, razdalja zbiranja pa dobrih 34 m. Delež linij za spravilo navzgor je 62%. Povprena koliina lesa na ciklus je 1,04 m3 (1,12 t), na linijo pa 300 m3,od tega 83 % listavcev. Spremljanje koledarskega asa, za kar skrbi delovna skupina pri stroju, je dober pripomoek za dolgorono spremljanje in analiziranje niza parametrov uinkovitosti pri delu, doseganja uinkov stroja inprimerjave med stroji ter tudi za obraunavanje opravljenega dela.
Keywords: koledarski čas stroja, žična naprava, študij dela, učinki pri delu, Syncrofalke, Tolminsko, Slvoenija
Published in DiRROS: 12.07.2017; Views: 4261; Downloads: 1807
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19. Stroški dela v različicah delovnih pogojev in izkoriščenosti strojev za sečnjoJanez Krč, Boštjan Košir, 2004, original scientific article Abstract: Sodobne tehnologije v procesu pridobivanja lesa zahtevajo skrbno analizo stroškov dela. V ta namen so analizirani nekateri tuji modeli računanja stroškov za strojno sečnjo. Predstavljamo program za analizo stroškov strojne sečnje, ki omogoča izdelavo kalkulacij za stroje za sečnjo in nadaljnjo analizo učinkov in stroškov pri različnih pogojih dela. Predvidene so različice za majhne in velike stroje ter za sestoje iglavcev in listavcev. Program omogoča analizo vplivnih dejavnikov na višino stroškov, med katerimi so najpomembnejši operativna stopnja izkoriščenosti strojev, analizirana v odvisnosti od učinkov in premikov stroja med delovišči, velikost delovišč, koncentracija sečenj in povprečno drevo poseka. Poleg navedenih vplivnih dejavnikov je mogoče analizirati tudi vpliv letne stopnje izkoriščenosti stroja na višino stroškov strojnega dela. Analize so pokazale, da se v splošnem pojavijo največje razlike v stroških dela pri kombinaciji koncentracije 30-40 m3/ha in 0,3 m3 povprečnega drevesa poseka.
Keywords: strojna sečnja, kalkulacija stroškov, izkoriščenost strojev, delovne razmere, premiki, model
Published in DiRROS: 12.07.2017; Views: 4233; Downloads: 1850
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20. Analiza učinkovitosti učenja strojnika na stroju za sečnjoŠpela Pezdevšek Malovrh, Boštjan Košir, Janez Krč, 2004, original scientific article Abstract: Članek obravnava načine učenja bodočih strojnikov za delo s strojem za sečnjo.Na prvem takšnem primeru v Sloveniji je opisan in analiziran potek učenja s simulatorjem in merjeni so časi posameznih postopkov pri dveh kandidatih. Opisano je delovanje simulatorja za učenje na stroju Timberjack 1270 D in potek enotedenskega tečaja. Narejena je primerjava med kandidatoma glede porabe časa in števila poškodb na virtualnem stroju in sestoju, ki jih je beležil program simulatorja. Podane so usmeritve za prihodnje študije in spremljanje učinkov strojnikov pri delu.
Keywords: stroji za sečnjo, strojna sečnja, simulator, učenje
Published in DiRROS: 12.07.2017; Views: 4489; Downloads: 1769
Full text (1,37 MB) |
