11. GIS-based model of wood precurement from stump to small sawmills in the Alpine region - a case studyJanez Krč, Boštjan Košir, 2009, izvirni znanstveni članek Povzetek: 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.
Objavljeno v DiRROS: 12.07.2017; Ogledov: 3657; Prenosov: 1722
 Celotno besedilo (2,54 MB) |
12. Assessing maximum loads when skidding wood uphill with tractorsBoštjan Košir, Jurij Marenče, 2008, izvirni znanstveni članek Povzetek: 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.
Ključne besede: tractor, skidding wood, maximum slope, maximum load
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4281; Prenosov: 1803
Celotno besedilo (1,19 MB) |
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, izvirni znanstveni članek Povzetek: 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.
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4121; Prenosov: 1817
Celotno besedilo (948,58 KB) |
14. Measuring the limits of uphill timber skidding with a WOODY 110 forestry tractorBoštjan Košir, Jurij Marenče, 2007, kratki znanstveni prispevek Povzetek: 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.
Ključne besede: forestry, tractor, skiiding, maximum slope, maximum load
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4231; Prenosov: 1923
Celotno besedilo (436,49 KB) |
15. Primerjava metod kalkulacij stroškov gozdarske mehanizacije na primeru žičniceJaka Klun, Boštjan Košir, Janez Krč, Mirko Medved, 2007, pregledni znanstveni članek Povzetek: 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.
Ključne besede: kalkulacija stroškov, gozdarski stroji, žičnice
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4165; Prenosov: 1839
Celotno besedilo (712,84 KB) |
16. Wheelslip in skidding with the AGT 835 T adapted farm tractorJurij Marenče, Boštjan Košir, 2007, izvirni znanstveni članek Povzetek: 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.
Ključne besede: skidding, farm tractor, wheelslip, measurement
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4343; Prenosov: 1916
Celotno besedilo (722,66 KB) |
17. Statistično spremljanje razvoja mehaniziranosti gospodarskih družb v obdobju od leta 1966 do leta 2002Simon Resman, Boštjan Košir, Mirko Medved, 2005, izvirni znanstveni članek Povzetek: 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.
Ključne besede: pridobivanje lesa, tehnična opremljenost, gozdarska podjetja, statistični podatki, Slovenija
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4156; Prenosov: 1818
Celotno besedilo (338,45 KB) |
|
