Skidding of fir roundwood by Timberjack 240C from selective forests of Gorski Kotar

The aim of the research was to determine the productivity of the cable skidder Timberjack 240C equipped with double-drum winch Konrad Adler HY 16 during skidding of fir roundwood from the Croatian mountainous selective forests of fir and beech. The research took place in the area of Delnice Forest Management, at two workplaces with different degrees of stone obstacles provided with strip road network. Skidder productivity was determined by the method of time and work study. The paper shows the results of some working characteristics of the researched skidder, such as: travelling speed of unloaded and loaded skidder, time consumptions of felling site work (loading) and roadside landing work (unloading), allowance time, realized load volume, fuel consumption, dependence of possible productivity and costs per unit on timber skidding distance

Integrated Oak Timber Protection from Ambrosia Bark Beetles: Economic and Ecological Importance in Harvesting Operations

Ambrosia bark beetles belong to a group of xylomycetophagous insects from the order Coleoptera, family Curculionidae and are characterized as important pests of oak timber. Galleries they form during their life cycle and infect with »ambrosia fungi« significantly decrease the economic value of oak roundwood. A state owned Croatian company »Hrvatske šume« Ltd. manages FSC certificated forests, where pedunculate and sessile oaks account for 22.6% in the annual allowable cut. Methods of oak roundwood protection, that used to be implemented in the past, are now banned in accordance with EU legislation as well as FSC criteria of forest protection. In these forest management conditions, it becomes necessary to introduce new biotechnical methods for oak roundwood protection. Available commercial products, flight barrier traps and synthetic semiochemicals, as well as pretreated insecticide treated polymer nets, were tested as means of integrated oak roundwood protection. Implementation of these products was tested in field conditions. Good knowledge of phenology of ambrosia bark beetles, thorough understanding of timber harvesting operations and field conditions that dominate in even aged oak forests, is crucial if applied methods are to be effective and taken on time. Field experiments conducted in this research showed that early seasonal deployment of semiochemically baited flight barrier traps can reduce the number of bark beetles that infest oak timber. It was also concluded that without additional protection with polymer nets, it is not possible to protect oak timber in compliance with strict FprEN 1316-1: 2012 E standards for oak roundwood classes, which do not allow any timber infestation in the highest quality grades (A and B quality class). Semiochemicals used as repellents during the research were ineffective. In the early months of spring, oak roundwood is at high risk of infestation at the roadside landings, where it is waiting to be transported

Contribution to Research on Virtual Production in Wood Processing and Furniture Manufacturing

Virtualni organizacijski oblici poduzeća (strateški savezi, partnerstva, mrežne i outsourcing veze, virtualni timovi i poduzeća) u suvremenom globalnom poslovanju postaju dominantni. Virtualne organizacije jedinstvenoga hijerarhijskog ustroja omogućuju racionalizaciju troškova poslovanja, efikasnije iskorištenje postojećih kapaciteta i fleksibilnost u odgovorima na izazove tržišta. Ako žele opstati u globalnom okruženju, hrvatska se poduzeća za preradu drva i proizvodnju namještaja moraju specijalizirati za područja u kojima mogu postići vrhunske svjetske rezultate i na njima temeljiti daljnje zajedničko poslovanje, razvijajući i njegujući partnerske odnose s komplementarnim poslovnim partnerima. Proces transformacije (virtualizacije) hrvatskih poduzeća za preradu drva i proizvodnju namještaja teče sporo i uz dosta strateških pogrešaka koje dovode do kriznih situacija i propasti poduzeća. Znatnija primjena koncepta virtualne organizacije na mikrorazini omogućila bi bržu i bezbolniju transformaciju klasičnih poduzeća, dok bi na makrorazini povećala konkurentnost cijeloga drvnog kompleksa.Virtual organizational forms of enterprises (strategic alliances, partnerships, networks and outsourcing connections, virtual teams and enterprises) become dominant in a modern global business world. Virtual organizations of unique hierarchy structure can provide the rationalization of business costs, more effective use of the existing capacities and flexibility in responding to market demands. If the Croatian wood processing and furniture manufacturing enterprises want to survive on a global market they have to get specialized in areas in which they can achieve top world results and based on such results develop their further business activities focusing their interest on partnerships with complementary business partners. Transformation process (virtualization) of the Croatian wood processing and furniture manufacturing enterprises is slow and accompanied with a lot of strategic errors, which can often cause crisis situations and closing of enterprises. Significant use of virtual organization concept would provide quicker and less painful transformation of traditional enterprises at a micro-level and increase competitiveness of the whole wood sector at a macro-level

Raziskava virtualne proizvodnje v lesni industriji

Enterprises with inflexible production structures can no longer survive in a turbulent market, as they cannot react to changes that would lead to their development. In order to satisfy specific customer needs related to quality, quantity, cost and delivery terms, it is necessary to restructure the existingenterprises according to the Taylor principle. One of reconstruction possibilities is the implementation of new co-operation forms that lead to virtual enterprises i.e. changeable networks. A changeable network can only achieve efficiency by means of a modern information and communication technology. This paper presents an idea of a changeable network that can be acceptable for all participants within a virtual enterprise.Podjetja z nefleksibilno proizvodno strukturo ne morejo več preživeti na turbulentnem trgu, saj ne morejo odreagirati na spremembe, ki bi lahko vodile v njihov razvoj. Zato, da bi zadovoljila specifične potrebe potrošnikov, povezane s kakovostjo, količino, stroški in dobavnimi roki, je nujna reorganizacija obstoječih podjetij po Taylorjevem principu. Ena izmed reorganizacijskih možnosti je implementacija nove kooperacijske oblike, ki vodi do virtualnih podjetij oz. spremenljivih mrež. Učinkovitost lahko zagotovijo samo spremenljive mreže, in to s pomočjo moderne informacijske in komunikacijske tehnologije. Članek predstavlja idejo spremenljivih mrež, ki jelahko sprejemljiva za vse udeležence v virtualnih podjetjih

Hrvatska komora inženjera šumarstva i drvne tehnologije donijela svoju prvu strukovnu smjernicu

Povodom donošenja prve strukovne smjernice Hrvatske komore inženjera šumarstva i drvne tehnologije »Smjernica za izradu Elaborata radilišta za radove u šumarstvu« opravdano se postavljaju pitanja: 1) Zašto su potrebne strukovne smjernice?, 2) Tko treba donositi strukovne smjernice?, 3) Tko inicira i kako nastaju smjernice strukovnih komora? te 4) Kakve trebaju biti strukovne smjernice? Iznesene ideje i stavovi putokaz su ovlaštenim inženjerima šumarstva koji će se u budućnosti na bilo koji način uključiti (kao predlagatelji, članovi radnih skupina ili davatelji primjedaba tijekom javnih rasprava) u postupak donošenja idućih strukovnih smjernica Hrvatske komore inženjera šumarstva i drvne tehnologije

Analiza kamenitosti i stjenovitosti terena za potrebe privlačenja drva

U radu je prikazana analiza kamenitosti i stjenovitosti površine GJ »Kupjački vrh«, NPŠO Zalesina, kao jedne od važnih značajki prometnosti terena koja ograničava kretnost šumskih vozila. Površinske prepreke (kamenitost i stjenovitost) snimljene su postavljanjem sistematskoga uzorka od 319 primjernih ploha, međusobnoga razmaka 100 m, veličine 10 × 10 m. Na svakoj je primjernoj plohi, temeljem prikazane metodologije, provedeno mjerenje visine i učestalosti površinskih prepreka (kamenitosti) radi određivanja razreda površinskih prepreka. Površinske su prepreke raščlanjene s obzirom na pojavnost u četiri skupine (pojedinačne, rijetke, srednje učestale, učestale), odnosno u četiri visinska razreda: H20 (10 – 30 cm), H40 (30 – 50 cm), H60 (50 – 70 cm) i H80 (> 70 cm). Analiza udjela pojedinih razreda površinskih prepreka pokazala je prevladavanje razreda 3 (djelomično neravan teren) na 39,59 % površine, ali i da razredi 3, 4 i 5 (razred 5 je najteži sa stajališta kretnosti vozila) zajedno zauzimaju više od polovice ukupne površine gospodarske jedinice (65,87 %). Postojeći podaci o kamenitosti pojedinih odjela i odsjeka iz opisa sastojina (obrasci O2 ili O3) osnova i programa gospodarenja šumama nisu dobar ulazni podatak sa stajališta kretnosti šumskih vozila, odnosno prometnosti terena jer govore samo o udjelu pokrovnosti površine. Stoga se predlaže uključivanje izmjere i procjene površinskih prepreka s obzirom na njihovu dubinu i visinu te učestalost kao jedne od sastavnica terenskih izmjera pri izradi osnova i programa gospodarenja šumama

Modelling of Downhill Timber Skidding: Bigger Load – Bigger Slope

Skidder mobility during timber extraction is defined by: 1) basic dimensional features of the vehicle, 2) ability to overcome obstacles during movement, 3) traction performance and 4) environmental soundness. Traction performance depends on the ground conditions (soil bearing capacity) and the total effect of all forces on the vehicle. In downhill skidding, the skidder is under great influence of parallel component of forces, adhesion weight and longitudinal terrain slope, which combined result in negative traction force, torque and thrust force. When the horizontal component of rope force is equal to zero i.e. the moment when the weight of the load and resistance to traction are in equilibrium, the slope angle α is a function of load mass distribution factor and skidding resistance factor. This is a »turning point« that can be defined as a critical slope because the load starts to push the vehicle downhill, which results in negative horizontal component of rope force. Depending on skidder Ecotrac 120V dimensional features, centre of gravity, load mass distribution factor, skidding resistance factor of previous research, five different loads were analyzed (1 to 5 tonnes) in order to define the critical slope angle for each of them. Critical slope for downhill skidding of 1 tonne timber is on longitudinal slope of –26%, for 2 tonne timber on –30%, 3 tonne timber on –34%, 4 timber on –38% and for 5 tonne timber on –43% of terrain longitudinal slope. Even though skidding bigger load increases vehicle mobility to even greater slope angles, the most important in downhill skidding, is to avoid blocking of the wheels, which will lead to a complete vehicle slippage and the driver must be constantly aware of that fact. The general recommendation should be that skidding small loads (1 to 3 tonnes) downhill is suitable for smaller longitudinal terrain slopes (up to maximum –34%), while the heavier the load, the further down the slope the skidder can go. The load of 5 tonnes »anchors« the skidder better and therefore it can go on terrain slopes up to –43%, during which less traction force is used (torque is used for braking) and skidder pulls the load by its own weight. It can be concluded that extending the operating range of skidder onto steeper slopes with heavier loads has the potential to decrease harvesting costs and increase productivity

Analiza kamenitosti i stjenovitosti terena za potrebe privlačenja drva

U radu je prikazana analiza kamenitosti i stjenovitosti površine GJ »Kupjački vrh«, NPŠO Zalesina, kao jedne od važnih značajki prometnosti terena koja ograničava kretnost šumskih vozila. Površinske prepreke (kamenitost i stjenovitost) snimljene su postavljanjem sistematskoga uzorka od 319 primjernih ploha, međusobnoga razmaka 100 m, veličine 10 × 10 m. Na svakoj je primjernoj plohi, temeljem prikazane metodologije, provedeno mjerenje visine i učestalosti površinskih prepreka (kamenitosti) radi određivanja razreda površinskih prepreka. Površinske su prepreke raščlanjene s obzirom na pojavnost u četiri skupine (pojedinačne, rijetke, srednje učestale, učestale), odnosno u četiri visinska razreda: H20 (10 – 30 cm), H40 (30 – 50 cm), H60 (50 – 70 cm) i H80 (> 70 cm). Analiza udjela pojedinih razreda površinskih prepreka pokazala je prevladavanje razreda 3 (djelomično neravan teren) na 39,59 % površine, ali i da razredi 3, 4 i 5 (razred 5 je najteži sa stajališta kretnosti vozila) zajedno zauzimaju više od polovice ukupne površine gospodarske jedinice (65,87 %). Postojeći podaci o kamenitosti pojedinih odjela i odsjeka iz opisa sastojina (obrasci O2 ili O3) osnova i programa gospodarenja šumama nisu dobar ulazni podatak sa stajališta kretnosti šumskih vozila, odnosno prometnosti terena jer govore samo o udjelu pokrovnosti površine. Stoga se predlaže uključivanje izmjere i procjene površinskih prepreka s obzirom na njihovu dubinu i visinu te učestalost kao jedne od sastavnica terenskih izmjera pri izradi osnova i programa gospodarenja šumama