Marijan Šušnjar

• University of Zagreb

The paper deals with the analysis of the fuel consumption of skidders during timber extraction from thinning of even-aged beech forest on mountain terrain. Fuel consumption research was conducted on the Ecotrac 140V cable skidder over 8 working days at the same worksite during real timber extraction work. The worksite was organized so that the empt...

Rad se bavi analizom potrošnje goriva skidera pri privlačenju drva iz prorede jednodobne bukove sastojine na gorskom području. Istraživanje potrošnje goriva provedeno je na skideru Ecotrac 140V tijekom osam radnih dana na istom radilištu u stvarnim uvjetima privlačenja drva. Radilište je organizirano tako da se prazni skider kretao uzbrdo, dok je o...

Today in many countries and regions, forestry sector deals with a considerable shortage of forestry workers and faces the serious challenge of ensuring a qualified and sustainable workforce. Current global processes and structural changes, such as emigration from rural areas, aging of the population, unfavorable age structure of existing employees,...

The paper presents the process of electricity and thermal energy production in a cogeneration plant and the process of wood pellet production. The aim of this study was to analyze the energy gain—EROI for energy products that are created as a product contained in electrical and thermal energy and the energy contained in wood pellets. According to t...

Compiling the research on forestry ergonomics, which is still a marginal field in terms of the sheer volume of published forestry-related articles, gives a good foundation and guidance for future research and publishing. This review aims to compile, classify, and analyze forestry ergonomics publications in JIF (Journal Impact Factor) journals regar...

Labour force represents the sum of human physical and mental abilities used for the production of whatever kind of use values. In forestry, the performance of work operations, especially wood harvesting, represents a high-risk, physically intensive, and professionally very demanding activity, which inevitably requires a qualified and sustainable la...

A gasoline-powered chainsaw is still an irreplaceable tool in forest harvesting operations. Operating a chainsaw requires training and skill since it is a potentially dangerous tool if not operated according to the safety guidelines. Safely starting a chainsaw is often overlooked in practice which can cause serious physical injuries. To safely star...

The aim of this research is to measure the energy consumption and compare the cutting performance of three types of battery-powered chainsaws (Stihl MSA 200, Stihl MSA 220, and Stihl MSA 300). Tested chainsaws were powered by two different battery packs (Stihl AP 300 S and Stihl AP 500 S) with different energy capacity and output current when cutti...

The Ordinance on Occupational Safety and Health in Forestry proposes no more than 4 h of effective chainsaw work daily, while EU Directive 2002/44/EC proposes an EAV of 2.5 m/s2, and an ELV of 5 m/s2. The aim of this paper was to compare and assess the viability of the proposed restrictions. A case study in Croatia including 91 felled and processed...

Professionally trained, motivated, and responsible forestry workers are a fundamental prerequisite of successful forest production and an integral part of the modern, generally accepted paradigm of sustainable forest management. However, the forestry sector today is increasingly facing the problem of a shortage of forestry workers and the challenge...

The increasing importance of utilizing new technologies, such as GNSS (Global navigation satellite system) devices, total stations, drones, scanners, etc., in forestry has become evident with the development of these tools. Combined with precise GNSS devices, UAVs represent an efficient tool that facilitates field measurements and reduces time spen...

Forest cleaning, being an operation that requires investment, but the return on investment is due for the next generations, utilizes tools and methods that mostly haven't been humanized. Harmful vibration is still present in today's forestry operations, and new tools provide possible reduction of exposure to vibrations. Petrol chainsaw and battery...

Growing demand for forest machines that cost less to operate than current compared to traditional hydraulic and mechanical ones, along with regulatory pressures for lower emissions, is increasing manufacturers’ interest in developing electric and hybrid drives. While purely electric drives of forest machines meet a lot of bottlenecks (costs of the...

During forest harvesting operations, exhaust emissions from forest vehicles are released at different levels depending on several variables. This pollution released into the atmosphere is considered one of the main anthropogenic factors that negatively affect forest ecosystems. In this study, we analyzed exhaust emissions from a skidder diesel engi...

Hybrid powertrain presents a viable solution for reducing fuel consumption achieved by a powertrain electrification while maintaining the independence from the electric grid or a charging station. Due to the fact that skidders belong to the class of forestry machinery which is intended for field use, this operating independence is very important. A...

This paper deals with the use of debarking modifications of the conventional harvester head in the conditions of felling due to bark beetle calamity. For this purpose, a time study was established, in which the conventional heads were compared with the heads with debarking modifications on four research plots and two harvesters. The measurements we...

Skidders, as self-propelled machines designed to transport trees or parts of trees by trailing or dragging it from the woods to a landing area, are still extensively used as the main wood extraction equipment in most of the Europe and worldwide. The high price of new machines (and even higher for CTL technology) makes the second-hand skidder market...

The paper deals with the characteristics of three different types of power train hybridization of forest logging machines and with the benefits of reducing environmental impacts by comparing new technology with more conventional, older technology. New hybridization options that could be implemented in forestry machines are also discussed. The paper...

For the needs of fuel consumption analysis, a database for a period of 2 years was created for three types of skidders operating in two different management methods—even-aged and selective forests. A total of 436 skidders were processed in the database, of which 255 skidders worked in even-aged forests and 181 skidders worked in selective forests....

The exposure of workers to vibration is expressed as energy equivalent A(8), which is determined by the procedure clearly described in the international standard ISO 5349-1-2001. A(8) is a value that depends not only on the vibration level in certain operating procedures, but also on the duration of exposure. Research was conducted on Ecotrac 120 V...

Technical development and system optimization during the last decades have targeted more efficient, socially acceptable and ecologically sustainable ways to use forestry machines and tools. This is supported by the development of electronics and electrical components, as well as battery technology, without which it is impossible to imagine doing so...

U radu su prikazani rezultati istraživanja učinkovitosti skidera Ecotrac 55V. Istraživanje je provedeno u šumskom odjelu 89, gospodarska jedinica »Igman«, uz primjenu studija rada i vremena. Trajanje radnoga vremena ustanovljeno je »povratnom« metodom snimanja. Ovisnost vremena trajanja radnih operacija o utjecajnim čimbenicima utvrđena je uz primj...

Over the last decade, off-road vehicles have been increasingly hybridized through powertrain electrification in terms of additional electrical machine-based propulsion and battery energy storage, with the goal of achieving significant gains in fuel economy and reductions in greenhouse gases emissions. Since hybrid powertrains consist of two or more...

Problem izloženosti štetnim vibracijama u šumarstvu javlja se s primjenom prvih motornih pila u sječi i izradi. Iako je rad s motornim pilama bio višestruko brži, produktivniji te fizički manje zahtjevan od ručnog obaranja, motorne pile emitirale su velike količine vibracija i s vremenom je došlo do negativnog utjecaja na zdravlje šumskih radnika....

The paper presents a hypothetical conversion of a conventional cable skidder powertrain to its hybrid version. Simulations of skidder operation were made for two existing forest paths, based on the technical characteristics of the engine, transmission system and the characteristics of the winch. Fuel and time consumption were calculated per working...

Nowadays there are increasing demands in terms of reducing the cost of running forestry machines along with the regulatory pressures for lower exhaust emissions to improve the ecological indices and reduction of acoustic noise in order to better comply with industry ergonomic guidelines. Therefore, the producers of forestry equipment are increasing...

This paper presents a hypothetical conversion of a conventional articulated forestry tractor known as skidder to its hybrid counterpart by incorporating a battery energy storage system. Starting from the basic parameters of 84 kW diesel-powered skidder currently found in the national forestry company fleet, the quasi-static model of the skidder is...

Although professional chainsaws have come a long way regarding technical and ergonomic development since first introduced into forestry, they still remain a high-risk tool that can cause serious health problems. In this research, three types of used professional chainsaws were observed regarding harmful vibrations they emit and possible connection...

Stabilnost traktora osim uzdužnog i poprečnog kuta stabilnosti podrazumijeva i sigurnost sidrenja traktora pri privitlavanju drva. Privitlavanje predstavlja vuču drvnih sortimenta po tlu od mjesta izrade u sječini do šumskog vozila za privlačenje drva opremljenog sa šumskim vitlom. Kod određenog graničnog tovara i nagiba terena dolazi do narušavanj...

U radu je provedeno istraživanje petnaest različitih šumskih kamionskih skupova za prijevoz drva u vlasništvu poduzeća Hrvatske šume d.o.o. Zagreb, Uprava šuma podružnica Bjelovar. Osnovni podaci koji su korišteni za analizu šumskih kamionskih skupova za prijevoz drva su: prijeđeni kilometri (pun, prazan), ukupna potrošnja goriva, broj dana rada (u...

The main tool used in a forest cleaning is a billhook, a hand tool consisting of a hold and a hooked blade sharpened on both sides. Forest cleaning is physically very tiring and takes place under difficult working conditions (high temperature and humidity, dense vegetation, insects). Moreover, working with billhook is exclusively manual work and it...

Fuel consumption of forest machinery and vehicles depends mainly on terrain conditions, working methods, drivers’ skills, engine load under working conditions, engine speed, type and technical characteristics of the machine. In timber harvesting operations, fuel consumption is significant for both, economic (costs), and environmental issues (80-95%...

Soil disturbance is often an inevitable consequence of machine movements in the forest stand during which soil compression occurs and, depending on the soil bearing capacity, root system is prone to damage. In this paper, the analysis of soil disturbance was performed after harvester felling and cutting, and subsequent timber forwarding in thinning...

Regarding number of vehicles, forest roads are characterized by low traffic intensity, but on the other hand great values of ground pressure between wheels of timber truck units and forest road surface occur, often with pressures values above 80 kN which additionally causes damage of the upper and lower forest road layer. There are currently severa...

The main tool used in forest tending work is a hedging bill, a hand tool consisting of a hold and a blade sharpened on both sides. Working with the hedging bill is physically very tiring and takes place under difficult working conditions (high temperature, dense vegetation, insects). For purpose of humanizing the forest tending work, a tool that ha...

Background and Purpose: Fuel consumption in timber harvesting operations is significant for both economic and environmental reasons. In economic sense, one significant part of timber harvesting costs is reduced to fuel costs, and in environmental sense 80% to 95% of exhaust emissions and soot particles in forest machinery are in fact associated wit...

UDK: 630*31:630*36 In the paper is conducted comparison of the wheel slip of the two different skidders in the equal conditions of extraction (equal loads and slopes of the tractor road and skid trail). The first skidder in the research is ECOTRAC 120 V of the Croatian manufacturer Hittner d.o.o. with the mechanical transmission and the other skidd...

Today, LCA is one of the leading and most used tools for environmental management, but the application of LCA in forestry is still in an initial phase. Due to a high amount of different wood products which can be produced in forestry sector, production of raw material itself is not included enough in the whole LCA process. Raw wood products and bio...

The paper presents the features of the new tractor semi-trailer »Lika« equipped with »Palms« hydraulic crane. The semi-trailer is made in Croatia according to dimensions that have already been tested in forestry practice in Central Europe, while the hydraulic crane »Palms« is made in Estonia. An important feature of the studied forest semi-trailer...

During the transport of stacked wood for processing (pulpwood), it is essential to know the total load mass because the sale of these products is based on mass. The main goal of the research is to determine the mass distribution of fir pulpwood load that can be transported with different types of truck units and to compare it with the permitted axl...

In the last few years, with the start of wood biomass production from wood residues, the need for determining the quantity of extracted wood residuals on a landing site has appeared. The beginning of intensive usage of wood residues for wood biomass starts in lowland forest where all wood residues are extracted with forwarders. There are several wa...

Soil disturbance, as a result of the movement of forest vehicles, has a negative effect on the growth and increment of forest trees and hence should be kept at a minimum. Some of the measures for reducing soil disturbance are: selecting a suitable harvesting system, setting a skid trail network (with traffic surveillance) and oriented felling as a...

Timber haulage is the last phase of wood harvesting. Due to its characteristics, cycle operation, a lot of unloaded driving, high purchase price of truck units, transport of small amounts of cheap goods, high oil prices, high fuel consumption, timber haulage is most expensive phase of wood harvesting. Apart from high prices, timber haulage has a lo...

The present study was conducted on the slopes of the Bilogora mountain in the central region of Croatia. Logging operations were performed at two felling sites with two different silviculturual treatments: thinning was performed at worksite A, and a regeneration cut was performed at worksite B. A half-length harvesting method and the skidding of ha...

This paper describes an indirect method of determining exposure to vibration of skidder driv- ers using the Fleet Manager System. The hand-arm exposure of workers to vibration is expressed as energy equivalent A(8), which is determined by the procedure clearly described in the international standards ISO 5349-1-2001 and ISO 2631-1-1997. A(8) is a v...

This paper presents the history and tradition of forestry academic education in Europe. In the last few decades a lot of changes have occurred and forestry academic education has lost a high-level position in European society and economy. In many European countries, higher education forestry programs are just a part of the educational system of uni...

Axle load distribution has a great influence on skidder mobility during timber extraction on sloped terrain. Axle load distribution is affected by: 1) dimension parameters (skidder weight, center of gravity position and placement of horizontal rollers), 2) orientation and slope of terrain, 3) load characteristics and 4) factors of load distribution...

This paper shows the measurement of maximum pulling forces and pulling forces while the vehicle moves backwards for forest machines equipped with forest winches and anchor plates. The measurements were conducted on the following skidders: 1. Timberjack 240C with single-drum winch, without anchor plate, with fixed horizontal rollers, 2. LKT 81T with...

This paper presents the investigation of wheel index as the parameter describing the environmental acceptability of interaction between the vehicle wheel and soil during timber forwarding (extraction) in the stand. In the Croatian lowland forests, characterized by excessive soil moisture, as stated by Anić (2001) and Poršinsky (2005), special fores...

This paper describes the assessment of environmental viability of timber extraction by two vehicles – forwarder and tractor assembly of 1-m wood by two methods of mechanized forest residues management. In the first variant, the forwarder was first used for extracting industrial roundwood, and then for all the remaining parts of the tree as energy w...

In Croatian Forestry wood transportation is usually carried out by trucks with trailer (forest truck unit) and trucks with two-axle semitrailer (forest semitrailer assembly). As they travel on public roads, they are subject to severe legal restrictions on allowable loads of axles and the whole vehicle. The basic legal regulation that defines some t...

Vehicle movement in forestry is described by: 1) the basic dimensional features of the vehicle, 2) the ability to overcome obstacles during movement, 3) traction performance, and 4) environmental suitability. Traction performance depends on the ground conditions (soil bearing capacity) and the total effect of all forces on the vehicle. In this arti...

For quality and rational forest ecosystem management the existence of an optimal spatial laid network of primary and secondary forest traffic infrastructure is necessary. There are different parameters for the quantitative and qualitative assessment of the existing network of forest traffic infrastructure as well as to define unopened or insufficie...

For quality and rational forest ecosystem management the existence of an optimal spatial laid network of primary and secondary forest traffic infrastructure is necessary. There are different parameters for the quantitative and qualitative assessment of the existing network of forest traffic infrastructure as well as to define unopened or insufficie...

The research was carried out on the strip road where longitudinal slopes were determined by the leveling method as well as individual distances of the strip road of uniform slope. Skidders were used for carrying out traction tests in downhill and uphill skidding of 9 different loads. Measurement of wheel loads, wheel torques and components of rope...

The paper eals with performance of terrain leveler Vermeer T855 in forest fire road construction and carst melioration. Research was caried out in the Mediterranean region on southern part of Croatia (Dalmatia) exactly on the area of forest office Zadar and forest office Buzet. The research was performed during three weeks of the machine work and t...

The paper deals with performance of terrain leveler Vermeer T855 in forest fire road construction and carst melioration. Research was caried out in the Mediterranean region on southern part of Croatia (Dalmatia) - exactly on the area of forest office Zadar and forest office Buzet. The research was performed during three weeks of the machine work an...

This paper presents the results of measurement of mass and axle load of tractor assemblies. The investigation was carried out by measuring the basic dimensions and mass characteristics of 5 different types of tractor assemblies. The following technical features affecting the distribution of axle loads have been determined: type of tractor and semit...

This paper gives a survey of how a Fleet Management System may be used in monitoring the operation and research of forwarders. FM System is most frequently used in road vehicles (cars and trucks), but it has also found its application in some forestry machines such as forwarders (BU Osijek) and skidders (BU \ur|evac). In this case the system was in...

The paper deals with performance of terrain leveler Vermeer T855 in forest fire road construction and carst melioration. Research was ca ried out in the Mediterranean region on southern part of Croatia (Dalmatia) exactly on the area of forest office Zadar and forest office Buzet. The research was performed during three weeks of the machine work and...

The purpose of this study is to research the effects of different concentrations of mineral and biodegradable oils for chainsaws on seedling growth of pedunculate oak (Quercus robur L.) during two-year vegetation period. The paper also examines the influence of the above mentioned oils and their concentrations on the development of the seedling roo...

This paper presents the results of morphological analysis of 93 different types of farmi winches intended for in-stallation on three-point linkage farming tractors during timber skidding. Dependencies between certain pairs of technical characteristics of farmi winches were determined by morphological analysis. The following technical characteristic...

This paper presents the research whose aim was to assess the load of the so-called choker-man, who pulls out the steel cable of the forest winch, based on measuring manual forces and defining their output patterns, all in accordance with the criteria contained in the »Regulations on Protection at Work during Manual Load Transfer« (Official Gazet-te...

The results of this paper present the morphological analysis of nine different types of tractor assemblies used in forestry practice in timber forwarding from thinning operations of lowland forests. Among these tractor assemblies 4 types are older, equipped mechanical cranes. The remaining 5 tractor assemblies, manufactured more recently, are equip...

Background and Purpose: The role of environmental effects in timber harvesting has great importance in decision making and planning logging operations. Consequently, more emphasis should be put on a planning system so that environmentally sensitive sites for a certain harvesting system can be recognized and the most suitable machinery selected for...

The purpose of this study is to research the effects of different concentrations of mineral and biodegradable lubricants for chainsaws upon seedling growth and the initial growth of pedunculate oak (Quercus robur L.), the most significant forest tree species in the region of the lowland Croatia. Tests were carried out in two nurseries upon 1-m2-plo...

This paper presents the results of morphological analysis of the Croatian skidder ECOTRAC 120V, as well as the research of its productivity features in timber skidding from hilly terrain after preparatory felling and from mountainous terrain after selective felling. Morphological analysis was used for determining the dependence of morphological fea...

Rad prikazuje morfološku raščlambu različitih tipova hidrauličnih dizalica koje se ugrađuju na strojeve za izvođenje šumskih radova kako bi se vidjele različitosti njihovih tehničkih značajki i mogućnosti njihove primjene. Za potrebe raščlambe izrađena je baza tehničkih podataka 231 tipa hidrauličnih dizalica podijeljenih u četiri skupine s obzirom...

Istraživanje raspodjele opterećenja kotača skidera pri privlačenju drva provedeno je na traktorskom putu na kojem su metodom niveliranja utvrđeni uzdužni nagibi te pojedine udaljenosti traktorskoga puta jednolikoga nagiba. Skiderom su se izvodili vučni pokusi privlačenja devet različitih tovara uzbrdo i nizbrdo. Tenzometrijskom su metodom mjerene v...

This paper shows the daily portion of tree cutters' exposure to total dust or respirable fraction of oakwood during its cutting and processing. The research was carried out in a low-land part of Croatia in summer during processing fuel wood in thinning operations, and in winter during final cut of pedunculate oak stand. The measurements show that w...

This paper presents a morphological analysis of different types of hydraulic cranes installed on forest vehicles with the aim of determining their technical characteristics as well as possibilities of their use. A database of technical characteristics of 231 types of hydraulic cranes was compiled for the morphological analysis. Hydraulic cranes wer...

Research of wheel load distribution of skidders in timber extraction was carried out on a skid road where longitudinal slopes were determined by levelling method as well as distances on a skid road with the same slope. A skidder was used for timber extraction of 9 different loads in two directions - uphill and downhill. Values of vertical and horiz...

The research of soil compaction in timber skidding was carried out on two skid trails of uniform slope –15%and 30 %. The degree of soil compaction is shown by changes of water-air soil characteristics of the skid trail after a certain number of passes of a loaded skidder and by comparison between these values and the characteristics of untreaded so...

The classification of timber assortments of silver fir into quality classes depends on the occurrence of wood defects. Knots are the most common defects appearing on fir assortments. The aim of this research was to establish the influence of size of knots and their position/height on fir trees (Abies alba, Mill.) on classification into quality clas...

Research of dynamic loading of skidder at timber skidding was carried out on two skid trails with continuous slope of 15 % and 30 %. Research results are based on 19 tests of uphill and downhill skidding. Vertical and horizontal components of winch rope force, wheel torgues and wheel loads are measured in each skidding test. Measurement of mechanic...

This paper shows the results of measurement of daily exposure of cutters to respirable particles and total fir-wood dust during cutting and processing of dead standing fir-trees. The separators of non-respirable fraction (cyclones) are designed so as to imitate the separation of respirable particles in the respiratory system of a healthy adult pers...

This paper deals with the research of resistance differences in winching of logs with their thicker or thinner end turned forward.Winching represents traction of wood assortments on the ground from the felling site to the forest vehicle equipped with a forest winch. The winching coefficient is determined by the horizontal tractive force and weight...

It is a common practice to use forwarders (special forest machines) in skidding/forwarding of roundwood from felling site to roadside landing during forest harvesting operations in Croatian lowland forests. This paper shows suitability evaluation of the use of forwarder Timberjack 171 OB (6WD), whose mass amounts to 17 tones, by determination of it...