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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 empty skidder traveled uphill, and when loaded, it moved downhill. The skidder was equipped with measuring devices for collecting data from sensors, the motor, and data transfer. The key parameters measured include total fuel consumption (mL) and skidder GPS position, while slopes of skid trails and load volumes were measured directly on terrain. Fuel consumption (L, L/m3) was determined per work cycle and work cycle elements. The highest fuel consumption occurred while driving the unloaded skidder, accounting for 38% of the total. This is primarily because fuel usage during skidder movement is significantly affected by factors such as skidding distance, slope, and skid trail conditions, especially since the unloaded skidder was moving uphill. Guidelines for better and more efficient organization of work and reduction in fuel costs are presented, and the suitability of the skidder and harvesting system are considered based on the results of fuel consumption. [ABSTRACT FROM AUTHOR]

The handling of the remnants of rice crops in the field is not an easy operation, and farmers prefer burning, which causes air pollution, smog, and disease. This research reports the development of a novel precision crop seeder by handling the remnants of previous crops through mechanization. The precision seeder performed multiple operations in a single path, viz, chop residues, incorporate into soil, make mini trenches, and sow wheat with fertilizer application. The precision seeder has a 2040 mm working width, and specially designed C-type blades are used to shred the crop residue. A multiple-speed gearbox with a gear ratio of 1:0.52 is installed, with a further set of spur gears with 16, 18, and 20 teeth that provide 225, 250, 310, and 350 RPMs to the main rotor. In the middle of the seeder, after the main rotor shaft, 11 V-shaped trencher plates are fixed on the trencher roller for the making of trenches. The trencher roller is powered by star wheels, which showed good results. A zero-tillage-type sharp tip edge novel seeder unit was developed for the precise placement of seed and fertilizer. Seed and fertilizer were placed into the mini trenches through 11 seeder units through a ground wheel calibration system. The field capacity of the precision seeder was 0.408 ha/h and the operational cost was calculated 40.68 USD/ha. The seeder showed good results, with the production of 5028 kg/ha compared to conventional methods. The precision seeder provides a mechanized solution for wheat sowing with minimal operational costs by enhancing organic matter in soil with 13% more yield. [ABSTRACT FROM AUTHOR]

Among the various factors affecting soil compression during wood extraction, travel speed hasn’t received much attention. The aims of this study were to (a) assess the effects of two frequently employed wood extraction machines, namely a tractor (Massey Ferguson 285) and a skidder model (Timberjack 450C), equipped with different tire sizes and uneven axle loads with regard to forest soil physical properties and rut formation under various traffic frequencies and travel speeds, and (b) examine the relationship between travel speed and soil bulk density. Treatments included six different traffic frequencies (0, 1, 3, 6, 10 and 15 passes) and three travel speed levels (1, 3 and 5 m s-1) of the two tractors. The number of passes, machine type, and travel speed all show significant effects (p < 0.05) on bulk density, total porosity, and rut depth. The skidder exerted statistically significant. Bulk density positively correlated with traffic intensity in all examined levels of travel speed. Porosity in the topsoil (0–10 cm) decreased by an elevating number of passes and this trend was also evidenced as the travel speed decreased. Furthermore, the skidder created, in all cases, deeper ruts than those generated by the tractor. Considering the imminent end of the ban on wood harvesting in the study area in 2016, these insights have practical implications for forest management and wood extraction practices. Forest managers should carefully consider the choice of wood extraction equipment and operational parameters, especially travel speed, to minimize soil compaction and rut formation. The implementation of strategies that support sustainable soil management practices during the wood extraction are paramount to preserving the long-term health and productivity of forest ecosystems.

Copyright of Caspian Journal of Environmental Sciences is the property of University of Guilan & Association of Universities of the Caspian Region States and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Forests provide multiple services, products and values and finding ways to preserve their multifunctionality is important. However, all of the currently used harvesting systems produce some degree of environmental damage, potentially affecting the provision services on the long term. Skidding operations are common in many regions of the world. Skidding may suppose three operational steps: winching, strip-road skidding and landing operations. By using cables for winching, wounds are commonly inflicted to the residual trees, while the mechanical traction of logs may cause damage to the residual trees and soil. This study was designed to check if the use of pans during winching deployed in thinning operations of coniferous forests may help lowering the environmental impact in terms of damage to residual trees and soil, while accounting for operational efficiency of such operations. Four treatments were considered and framed around the winching direction (uphill, downhill) and the use of protective devices (use, nonuse) and detailed data was collected on the residual stand damage, soil damage and time consumption. The main finding was that uphill winching by the use of a pan performed the best in terms of lowering the environmental damage. It shown the smallest wounds by their average area per tree, the lowest number of wounds per tree, the lowest rate of wounding per hectare, as well as one of the lowest rates of soil damage. By excluding delays, working with a pan did not cause additional time consumption, supporting acceptable rates of operational efficiency. Further experiments would be needed to validate and extend the results of this study, as the forests and their type of management are heterogeneous systems in terms of terrain configuration and slope, soil, species, stand density, removal intensity, operational timing and operational conditions. [ABSTRACT FROM AUTHOR]

In order to solve the problem of low skidding efficiency of plantation and secondary forest, according to the characteristics of plantation, a self-propelled crawler skidder for forest residues was designed. The key components of the skidder were designed and calculated, and the finite element analysis and optimization of the frame were carried out to ensure the rationality of the design. The stability of the skidder on the slope and the obstacle is analyzed, and the simulation analysis of the slope and the obstacle is carried out in the computer aided engineering software package Recursive Dynamic. Through the 20° climbing experiment of the prototype and the obstacle crossing experiment of 150, 200 and 250 mm high obstacles, the results show that the skidder can effectively pass through 20 ° slope and 250 mm height obstacles. The design of the skidder designed in this paper is reasonable and meets the conditions of forest traffic. [ABSTRACT FROM AUTHOR]

The negative influence of timber harvesting on the forest environment is reflected through damage to the residual trees, regeneration, and forest soil. Considering that skidding, a popular extraction method, can cause substantial and severe damage to the remaining stand, the aim of this research was to determine damage to residual trees during skidding by an LKT 81T cable skidder, including oxen bunching. The research was conducted in eastern Bosnia and Herzegovina, in an uneven-aged mixed fir (Abies alba Mill.) and spruce (Picea abies L.) forest with pine (Pinus sylvestris L.) on limestone soils. Tree felling was conducted using a Husqvarna 372 XP chainsaw. Extraction operations caused damage to 6.31% of the residual trees in the stand. The most damage was "removed bark" (65.34%) and occurred on the lower parts of the tree, the butt end (55.11%) and root collar (32.39%). The average size of the damage was 197.08 cm2. A statistically significant correlation was found between the damage position and the diameter at the breast height (p < 0.05) and the damage position and damage size (p < 0.01) by Spearman correlation analysis. The conducted analysis by the chi-squared test showed that there is a statistically significant difference in the proportion of damage for trees with different distances to the nearest skid road (p = 0.0487), but the share of damaged trees did not decrease by increasing the distance from the skid road. [ABSTRACT FROM AUTHOR]

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 electric components, battery durability, duration of charging, access to the electrical grid, size of batteries that can ensure enough energy for 8 h working time), electric hybrid drives offer a favorable solution for the propulsion of forestry machinery in terms of lower fuel consumption and improved efficiency. Among all forest vehicles, specialized forest tractors (skidders), so far, have not been considered for forest vehicles with hybrid drive capabilities. A skidder is a forest-articulated self-propelled vehicle for pulling trees or parts of trees. In most countries in southern Europe, the use of skidders equipped with forest winches is the most common technique for timber extraction. The first goal of the research is to develop methods for measuring the energy consumption of skidders at different operating tasks and under different field conditions. Research was performed on the skidder Ecotrac 140V (from Croatian producer Hittner Ltd.) during timber extraction in mountainous terrains in Lika–Senj County. The skidder was equipped with a measuring device WIGO-E (Telematic Data collector) gateway with an integrated GPS system, which ensured data were collected from sensors and motor and stored in a computer via CANBUS and data transfer with GSM to Web platforms. Additionally, a fuel-flow meter was installed on the skidder. Data on fuel consumption (mL), position (traveling route), detection of winch work, engine rpm (min−1), engine torque (% of max), throttle position (%), and engine temperature were measured with a sampling frequency of 5 s. Furthermore, skidder load volumes per cycles and slopes of tractor paths were constantly measured. The paper shows the skidder's energy consumption per day, work cycle, and individual work procedure with regard to the size of the load, the slope of the tractor path, and the direction of movement based on overlapping and merging all measurement data. Using mathematical and simulation models of the drive with defined operating cycles obtained by measurement, the possibilities of the hybrid drive and the dimensions of the elements of the hybrid drive (internal combustion engine, electric motor, batteries, control unit) were determined and are presented in this paper. [ABSTRACT FROM AUTHOR]

This paper investigates potential uses of a novel direct driven electro-hydraulic systems for articulated forestry tractors (skidders), due to these systems having notably higher energy efficiencies compared to classical electro-hydraulic systems that are currently being used in skidders for steering, lifting the front and the rear plate, as well as for operating the double-drum winch. A detailed analysis of the skidder rear plate mechanism is carried out, and static force profiles of hydraulic cylinders are obtained for the rear plate based on mechanism dynamics and measurement data from the literature. Thus, obtained results have been used to emulate the real-life force profiles in laboratory experiments featuring both the classical and the proposed direct driven hydraulic systems for the purpose of comparative analysis of their energy and fuel efficiency. These results are subsequently used to estimate the skidder fuel consumption and possible fuel savings over the entire vehicle life span for the realistic vehicle utilisation scenario. The main result is that fuel consumption can be reduced up to five times in the case of direct driven hydraulic system, thus effectively resulting in return of investment period of about four years in the case of skidder being retrofitted with direct driven hydraulic system. [ABSTRACT FROM AUTHOR]

Forest mechanisation plays an important role in increasing labour productivity and reducing production costs. This work aims at evaluating various logging scenarios in Calabrian pine high forests, considering technical, economic and environmental aspects. The cut-to-length system was adopted and structured as follows: felling and processing operations were carried out using a medium-sized chainsaw while extraction of the processed material was carried out using three different vehicles for timber extraction: (i) by cable skidder, (ii) by grapple skidder and (iii) by a forwarder. The methodology was based on productivity analysis and production cost analysis, while for environmental performance, the life cycle assessment (LCA) approach was adopted. The selected functional unit (FU) was referred to as 1 h of logging operations. However, to assess the resulting usefulness, further analyses were performed using an alternative FU consisting of 1 m3 of round wood. The study's outcomes show the complexity in achieving an optimal balance between productivity, economic aspects and sustainable management in forest operations. [ABSTRACT FROM AUTHOR]

Skidding is an important element of harvesting operations, which contributes to the extraction of wood. A skidder can be used in different types of harvesting operations, such as thinning, clear fell, native forest thinning or salvage work. The main goal of this article was to review the available stud-ies on productivity of skidding operations in coniferous forests/ plantations. Information on skid-der productivity was collected from publications and then was classified in three regions, including North America, Europe and the Southern Hemisphere. The parameters affecting machine productivity included machine type/ size, tree volume/ log volume/ load volume, average skidding distance and slope of the ground for each reported productivity. The average productivity reported in the published reports ranged from 9.3 m3/PMH to 78.0 m3/PMH. Detailed information and conclusions collected from various studies can be of use to forest academic and industry users to gain knowledge about vari-ations of skidder productivity in different regions and site/ operation conditions, which can be helpful for predicting, controlling and improving current levels of productivity.

Mountainous hardwood mixed stands offer challenges to timber harvesting operations in practice, including a harsh climate, variable topography, steep terrain, and large-sized timbers. This paper aims to develop productivity and cost models for a mountain-ground-based harvesting operation across the terrain (e.g., slope conditions), stand (e.g., tree volume) environmental (e.g., weather), and yard (e.g., winching distance) variables and to assess GHG emissions related to the equipment in use. This development was implemented in a timber harvesting practice under single-tree selection in mountainous forests of Iran where a motor-manual chainsaw is used for felling and a rubber-tired cable skidder is used for log extraction. The average delay-free productivity was 4.55 m3 for felling and 14.73 m3 h−1 for skidding. Lower production costs and higher productivity rates were observed over the gentle slopes and in sunny conditions. The average production costs ranged between USD 4.27 m−3 for felling and USD 5.35 m−3 for skidding. The average emissions ranged between 0.96 kg m−3 for felling and 7.06 kg m−3 for skidding in snowy conditions over steep slopes. The study’s results confirm avoiding harvesting operations on steep slopes (greater than 35%) and in extreme weather conditions to obtain higher work efficiency and to minimize adverse effects of machinery on forest ecosystems. The results should be of use to harvest managers and forest planners considering the application of ground-based harvesting operations using a semi-mechanized system on a range of operating conditions in mountain hardwood stands. [ABSTRACT FROM AUTHOR]

Temperate forest soils are an important sink for methane (CH4); however, disturbance through forest management and the creation of skid trails may significantly decrease soil's ability to uptake CH4 or in some cases cause CH4 emissions. Skid trails might also be expected to show reductions in carbon dioxide (CO2) flux due to anaerobic conditions and reduced root activity. Studies to date have investigated skid trail greenhouse gas flux dynamics on experimentally created skid trails, which may not experience the full extent of traffic intensity or contain the various microsites found in actual harvested areas. We investigated variation of CH4 and CO2 fluxes based on traffic intensity, trail topography, and trail microsites in selection-managed hardwood forests in the Haliburton Highlands of Ontario, Canada. Skid trail soils showed reduced CH4 uptake, and primary and secondary trails were found to commonly be a CH4 source, especially on lower slope locations and on wheel track and trail middle ridge microsites. Skid trails also showed high CO2 emissions in the same areas. CH4 emissions on skid trails were correlated with low surface soil porosities and high soil moisture contents, which were found to occur most frequently on highly impacted trails, in low-lying areas, and in the wheel tracks and trail middle ridges. Scaling up, skid trails offset ~ 45% of CH4 uptake in untrafficked soils, an effect that should be accounted for in future greenhouse gas budgets of managed forests. [ABSTRACT FROM AUTHOR]

Today, skeletal musculoskeletal disorders are one of the most important occupational health issues and have a high prevalence in almost all occupations, and preventing it involves evaluating and modifying working conditions. This study aims at assessing the risk factors of musculoskeletal disorders of work by QEC in forestry workers of two regions of Guilan and Mazandaran forests. In this study, statistical population included 51 workers in three jobs of felling and bucking, skidder driver, and manual loading worker were studied by census method. The Nordic questionnaire and QEC method were used for determining the prevalence of musculoskeletal symptoms and assessing the risk of these disorders, respectively. The results showed that the highest prevalence of musculoskeletal disorders was in the waist, neck and back segments, respectively. The significant relationship between weight, body mass index, work experience and smoking with musculoskeletal disorders was observed. Results of QEC evaluation showed that the 72.6 percent of worker are in risk level of 4, while these values for risk level 1, 2, and 3 were 7.8, 9.8, and 9.8, respectively. In vibration exposure, speed of operation and stress about 64.7, 62.7, and 70.6 percent of worker were in high and very high levels. The results indicate a high prevalence of disorder among workers. The main ergonomic problems in study area include inappropriate physical condition, bending and twisting of the waist, lifting and carrying heavy loads, vibration, speed during work and stress.

This study was conducted in order to estimate the economic life of two models of rubber-tired skidders, namely Timberjack 450C and HSM 904, in Iranian Caspian forests. The total annual costs and average cumulative cost of skidders were calculated by life-cycle costing analysis. The economic life of the machines was estimated by both the cumulative cost model and cost minimization model. The results indicated that the economic life of Timberjack 450C and HSM 904 is 7,700 h (at the end of the 11th year) and 15,300 h (at the end of the 17th year), respectively, using the cost minimization model. Furthermore, the results indicated that the economic life of Timberjack 450C and HSM 904 is 9,100 h (at the end of the 13th year) and 11,900 h (at the end of the 21st year), respectively, using the cumulative cost model. The cumulative cost model estimated the economic life of skidders longer than the cost minimization model.

The study used time studies and cost analysis to assess potential economic benefits from site preparation cost reductions resulting from producing coarse woody harvesting residue (CWHR) for bioenergy. In contrast, previous studies have predominantly used anecdotal estimates of site preparation costs. The study was performed in a recently clearfelled 15-year-old plantation of Eucalyptus globulus (Labill) in Tasmania, Australia. The study area consisted of the control area (0.51 ha), containing ~35 m3 ha-1 of CWHR and the CWHR harvest area (2.47 ha), containing =12 m3 ha-1 of CWHR. The control area had been harvested with a harvester - forwarder system, which left all harvesting residue (HR) onsite, whereas the CWHR harvest area had been harvested with a feller-buncher - skidder - processor system which removed most of the HR. The latter site was used to simulate an area where CWHR had been harvested. The study examined productivities and costs of machines performing site preparation in each area. The preparation of the control area site was performed with an excavator that windrowed CWHR, followed by a skidder-mounted plough constructing planting furrows. Residual CWHR post-windrowing was <1 m3 ha-1. Productivities and costs were 0.53 ha PMH0 -1 and AUD$319 ha-1 for the excavator and 1.1 ha PMH0 -1 and AUD$139 PMH0 -1 for the skidder-mounted plough. The excavator was not required in the CWHR harvest area. In this area, skidder-mounted plough productivity and cost were 1.16 ha PMH0 -1 and AUD$109 ha-1 suggesting CWHR reduction to =12 m3 ha-1 could reduce site preparation costs by AUD$319 ha-1. Further studies on costs and revenues associated with CWHR removal and sale are required to determine net economic benefits and determine excavator cost and productivity for a range of CWHR quantities. [ABSTRACT FROM AUTHOR]

Skidding is an important element of harvesting operations, which contributes to the extraction of wood. A skidder can be used in different types of harvesting operations, such as thinning, clear fell, native forest thinning or salvage work. The main goal of this article was to review the available studies on productivity of skidding operations in coniferous forests/ plantations. Information on skidder productivity was collected from publications and then was classified in three regions, including North America, Europe and the Southern Hemisphere. The parameters affecting machine productivity included machine type/ size, tree volume/ log volume/ load volume, average skidding distance and slope of the ground for each reported productivity. The average productivity reported in the published reports ranged from 9.3 m3/PMH to 78.0 m3/PMH. Detailed information and conclusions collected from various studies can be of use to forest academic and industry users to gain knowledge about variations of skidder productivity in different regions and site/ operation conditions, which can be helpful for predicting, controlling and improving current levels of productivity. [ABSTRACT FROM AUTHOR]

• Skidding and forwarding are the two options for ground-based forest operations. • Among practitioners, skidding is generally considered more impactful than forwarding. • Skidding in actually more impactful regarding the damages to residual stand. • Forwarding causes stronger soil compaction than skidding. • Application of Best Management Practices is fundamental to limit the impacts of both skidding and forwarding. The disturbance that ground-based extraction operations can imply on the forests ecosystem is an issue which demands more attention. Skidding and forwarding are the two most common ground-based extraction systems. While skidding implies to partially or fully dragging the logs on the ground, in forwarding, timber is transported on a deck thus avoiding direct contact with the soil. Generally, skidding is considered to be more impactful than forwarding in relation to the amount of disturbance on forest soil and residual stand. However, the framework depicted in current literature is not so strict. While skidding actually implies a higher level of damage to residual stand, the situation concerning disturbance to forest soil is much more complex. The dissimilarities in the results from various studies on this topic have shown the level of complexity. The lack of research investigating the consequences of the two extraction systems on the overall forest ecosystem is evident. Only a few studies were focused for example on the implications on biodiversity. However, the beneficial effects of best management practices, such as the application of snatch blocks during winching or positioning brush mats on the skid trails/strip roads to reduce soil compaction, have been clearly demonstrated. [ABSTRACT FROM AUTHOR]

TAF is the acronym for Articulated Forestry Tractor – a heavy vehicle uses in a logging operation for pulling cut trees out of a forest, in a process called “skidding”. TAF use a cardan shafts transmission from the gear box (CV) to distribution box (CD). The distribution box split the movement thru axels or winch. The study applied the cardan theory on a specific case and based on the numeric results a few design modifications are proposed for reducing the angular velocity pulse on the CD input shaft. Theoretical results may have a significant importance in practice, impacting the reduction of transmission noise and vibrations - already claimed in the case of the distribution box for the current constructive solution. An original AutoLISP program are made in order to analyze and optimize the transmission, with graphical results.

The paper dwells upon the necessity to increase the operating life of the toothed gearing of skidder transmission by means of strengthening by complex borating. The methodology of comparative testing of tooth gear as well as the stand construction are described. The causes of destruction of tooth gear surface strengthened by different methods have been determined.

It is now established that the main causes of failure of the transmission parts of the forest machines is wear of their working surfaces. The destruction of the contact surfaces of bevel gears front axle of skidder TTP-401 during its operation is usually connected, with the formation of plastic deformation on the teeth. According to modern concepts of the theory of the destruction of the details revealed that after the formation of plastic deformations leads to microcracks, the development of micro tracks depends on the magnitude and sign of residual stresses. This article presents dependance graphs of vibration acceleration bevel gears front axle skidder subiect to the method of hardening.

The operating conditions of forest machines are analyzed. Transmission parts disabled as a result of intensive wear have been determined, their fracture mechanism has been established. A technique for diffuse impregnation of component parts with powdered mixtures containing boron, aluminum and silicon is offered. An optimal composition and temperature for diffuse impregnation of component parts operating under dynamic loading has been specified. Microhardness of surface and subsurface layers has been studied. Technique for abrasion testing is offered, comparative testing of carburized and borated samples has been carried out

Copyright of Works of the Faculty of Forestry University of Sarajevo is the property of Faculty of Forestry University of Sarajevo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study was conducted in order to estimate the economic life of two models of rubber-tired skidders, namely Timberjack 450C and HSM 904, in Iranian Caspian forests. The total annual costs and average cumulative cost of skidders were calculated by life-cycle costing analysis. The economic life of the machines was estimated by both the cumulative cost model and cost minimization model. The results indicated that the economic life of Timberjack 450C and HSM 904 is 7,700 h (at the end of the 11th year) and 15,300 h (at the end of the 17th year), respectively, using the cost minimization model. Furthermore, the results indicated that the economic life of Timberjack 450C and HSM 904 is 9,100 h (at the end of the 13th year) and 11,900 h (at the end of the 21st year), respectively, using the cumulative cost model. The cumulative cost model estimated the economic life of skidders longer than the cost minimization model. [ABSTRACT FROM AUTHOR]

The development of technology and the means of labour in the technological process of forest harvesting in FBiH mainly depends on the factors related to the specific manner of forest management. The dominant share of mixed tall forests with natural regeneration, the selective manner of management and rather difficult natural conditions have resulted in the application of the cut-to-length method and to a lesser extent, the tree-length and semi-tree-length methods. On the basis of expert classification of the development phases in forest harvesting, it can be noted that wood assortment production in FBiH is currently partially mechanised. With the aim of defining measures for increasing productivity, lowering the costs and a greater humanisation of work, there has been an analysis of the current state of the means of work in all three phases of forest harvesting. The analysis included the following parameters: number of means in different phases, the type, the average age, ownership and technical planned obsolescence. All the data were collected through a survey which included all stakeholders (cantonal forest companies and private contractors). The results showed a satisfactory state only when chainsaws are concerned, i.e. the rather cheap tools. Other equipment (adapted tractors, skidders, trucks, etc.) has largely reached planned obsolescence. Their old age results in a low level of utilisation, i.e. an insufficient amount of working hours per year which eventually leads to a decrease in productivity and increase in expenses. Based on the data, it can be concluded that it is necessary to begin the process of new mechanisation procurement and the replacement of existing, time-worn and technologically obsolete machines with new ones. At the same time, it is clear that, in the conditions of low availability of investment capital and cheap labour force, this has to be a gradual process. In relation with this, the process should start in the most expensive phase - timber extraction, i.e. the phase in which the economic efficiency is unquestionable.

Forests in southern Italy are mainly located in mountainous areas, where ground-based extraction is still the most common harvesting technique. In particular, 60% of southern Italy's forests are on slopes with an angle of inclination between 20-60%. The low level of mechanization in forest operations is due to the difficult site conditions, as well as the small-scale characteristics of both the forest owners and the harvesting contractors. The most common work method uses chainsaws to fell the trees, and animals or farm tractors equipped with winches for bunching and extraction. This study assesses the productivity and cost effectiveness of extraction with a purpose-built John Deere 548H skidder, including a comparison of winch and grapple configurations. The results show that the productivity of skidding depends on distance as well as the condition of the skid trail. The number of trees per cycle and volume of each load also had a clear effect. While large purpose-built skidders represent a significant investment, this study demonstrates that the productivity is very high compared to traditional extraction methods and the resulting extraction costs are very competitive. As such, this study indicates that, over time, southern Italian harvesting operations should invest in purpose-built harvesting systems. [ABSTRACT FROM AUTHOR]

The paper aims to present some of the ecotechnological concepts in logging, applicable in our country. The first part of the paper defines the new technologies of logging in the current concept, as well as the modern ecoproductive machinery intended to be used with the new technologies. The work continues with the presentation of the material and the research methods used. Thus, books, magazines, brochures and international databases were used. The research methods used were: bibliographic documentation and practical experience, as well as analysis and synthesis for the elaboration of the results and conclusions of the study. In the results and discussions are presented the basic principles regarding the ecotechnology in the logging and respectively the ecotechnological trends toghether with the characteristics of the current systems and their swot analysis. The paper ends with the conclusions that bring together the most important ideas regarding the ecotechnological concepts in the logging as well as the most pertinent strengths and weaknesses of the swot analysis realized. [ABSTRACT FROM AUTHOR]

Natural calamities (especially windthrows) may generate difficultwork conditions in timber harvesting operations. When associated with the reduced accessibility conditions, the work conditions become even harder. This study investigates the time consumptions on specific work elements in timber skidding, develops time prediction models for timber skidding work elements and assesses the production rates for timber skidding in reduced accessibility stands where windthrow salvage cuttings were applied.Following a time study done for two skidders (TAF 690 OP and TAF 657)operating simultaneously in the same felling area, it has been found that, in average, in a delay free skidding cycle time, lateral winching accounted for a share of 26-33%, on-trail skidding accounted for a share of 64-71% and landing operations accounted for a share of 3%. Total delays accounted for 51% and 43% of the total work time in the case of TAF 690 OP skidder and TAF 657 skidder, respectively. Regression models for lateral winching(both skidders) revealed that the winching distance and the number of logs were the relevant predictors for the time consumption estimation (p

We present research results of timber skidding by a Timberjack 450C skidder in the path cutting of pine trees in Shafaroud watershed. Time studies were conducted to quantify the productivity and perational cost of skidding by a skidder in a plantation in even terrain conditions in Shafaroud, northern Iran. A linear regression model was applied for finding the relation of dependent variables such as total time consumption and productivity with appropriate independent variables. The most influencing variable for skidding were skidding distance, number of logs in each turn and load volume. The results indicated that the total production with and without delays was 5.17 and 5.98 m3.effective h-1, while the production cost with and without delays was 13.7 and 11.91 USD.h-1, respectively.

This research compared roadside chipping and road side processing systems. Two sites planted with Eucalyptus globulus were selected to study these harvesting systems. A time and motion study was applied to collect the data for both harvesting systems. The working cycles for each machine were recorded as well as the variables af­fecting the working productivity. Using the multiple regression method the appropriate models were developed. The results showed that the productivity of feller-buncher and processor was significantly affected by tree size. Productivity of skidders was dependent on extraction distance and load weight. Productivity for road side processing was higher than for road side chipping, which resulted in a lower unit cost. The unit cost (from stand to the mill) for road side processing and road side chipping averaged 22.68 AUD.t-1 and 21.07 AUD.t-1, respectively.

The felling and skidding damage to residual trees was investigated in a selectively cutting operation in the Caspian forest of Iran. The logging operation was performed by chainsaw and cable skidder. Prelogging, after felling and skidding operations residual tree injuries (species, DBH and damage) were inventoried by systematic plot sampling. Two types of tree damage were observed: destroyed and injured. In this study felling operations mainly injured trees whereas skidding was the main cause of destruction. The percentage of destroyed and injured residual trees by felling operations was 1.4% and 3.4%, whereas the percentage of destroyed and injured residual trees by skid­ding operations was 5.2% and 11.1%. About 87% of destroyed trees were found in the DBH class smaller than 22.5 cm. Maple and Alder were the most damaged trees among the other trees species. Damage to the lower bole and wood damaged intensity were the most common type of injury. To reduce the stand damage, skid trails should be planned before felling and felling directions should be predetermined. In the selection cutting management, limiting logging damage to residual trees must therefore remain a major objective.

This paper presents the results of research of Timberjack 240C tractor equipped with double-drum winch Adler HY16 in tree-length skidding method. The research was conducted in Euro-American poplar clearcut using time and work study method.Timber processing was done by teamwork of two fellers, one tractor driver and one feller-crosscutter (Fig. 3, Fig. 4 and Fig. 5). The volume of 759.03 m3 was skidded in 88 cycles from an average skidding distance of 760 m. The average load volume was 8.63 m3, and it consisted of 5.2 pieces with an average volume of 1.66 m3.During the research the tractor accomplished 68.63% of total time as effective time with delay time of 31.37% (Fig. 6). Travel unloaded accounted for 14.39% of total time, travel loaded 23.91%, felling site work 14.33% and landing work 16.00%. Daily output of 63.25 m3/day was achieved with average total time consumption of 359.32 min/day. The said total time consumption accounts for 78.86% of the legal working time (480 min).Variable times (travel loaded and unloaded by skid trails and landing, line pulling and winching) were analyzed by mathematical and statistical methods (Fig. 7, Fig. 8, Fig. 9 and Fig. 10). All other effective times were regarded as fixed and calculated as averages of recorded time.In effective time per turn, for skidding distance of 600 m (skid trail) plus 150 m (landing), travel times account for 18.14 min and felling site and landing work times account for 15.91 min. The effective time per turn, for skidding distance of 600 m (+150 m), is 34.05 min. With determined allowance time factor of 1.30, total time is 44.36 min. The average travel speed on skid trails is 6.52 km/h for unloaded tractor and 3.87 km/h for loaded tractor. The average travel speed on landing is 5.61 km/h for unloaded tractor and 3.73 km/h for loaded tractor (Table 2). The average speed of line pulling for the left drum is 0.97 km/h and the average speed of winching is 1.02 km/h. And for the right drum, the average speed of line pulling is 0.94 km/h and the average speed of winching is 0.85 km/h. (Fig. 3) Standard time of skidding ranges from 3.71 min/m3 (100 m) to 6.29 min/m3 (1000 m).The daily output for the average load volume ranges between 129.52 m3/day for skidding distance of 100 m and 76.34 m3/day for skidding distance of 1000 m. For skidding distances from 100 m to 1000 m, the skidding cost ranges from 22.18 HRK/m3 to 37.63 HRK/m3. The impact of different average load volumes on daily output and skidding cost is shown in Table 5 and Fig. 11.The results of this research show that Timberjack 240C tractor belongs to a group of highly-efficient special forest timber skidding machines. The principle of load size effect, as one of the key factors of timber skidding, on skidding productivity in different skidding distances has been proven by this detailed research. Hence, by increasing the load volume and decreasing the average skidding distance, the productivity of this tractor is significantly increased, thus lowering the cost per unit.

The optimum road spacing has been studied by many researches. It is an important step of forest road network planning. The goals of this study are determining the optimum road spacing in Kheiroudkenar forest of Nowshahr in Northern Iran and study of effect of kind of skidder on skidding cost and road spacing. Continues time study method was used to determine the production rate of TAF and Timberjack 450 C skidders in two districts of Kheiroudkenar forest. The production models were developed using stepwise regression method with 46 working cycles for TAF and 44 for Timberjack. The total road construction and skidding cost were calculated for different road spacing for both skidders in one-way and two-way skidding. Based on minimizing the sum of the road and skidding costs, the optimum road spacing was estimated as 1714 m and road density of 5.8 m/ha for two-way skidding by Timberjack and estimated optimum road spacing of TAF was 1600 m and road density of 6.25 m/ha. For one-way skidding, the optimum road spacing of Timberjack was 1143 m and road density of 8.8 m/ha, for skidding by TAF, the optimum spacing was estimated as 1114 m and road density of 8.97 m/ha. The existing road density of Timberjack and TAF skidding sites was 28.16 and 17.11 m/ha respectively which are higher than optimum density. The study of variants method is applied to find the optimal network for existing network in Namkhaneh district.

Este trabalho teve como principal objetivo a avaliação técnica das atividades de extração de madeira usando tratores florestais arrastadores skidders equipados com rodado de pneus e com rodado de pneus recoberto com semi-esteiras. A avaliação técnica consistiu em determinar os índices de produtividade da operação de extração da madeira por meio de um estudo de tempos e movimentos, em que a operação foi dividida em fases do ciclo de trabalho. Foram determinadas as produtividades das máquinas em diferentes situações de distâncias de extração e declividades de terreno. Os resultados indicaram que o tempo médio do ciclo operacional do skidder com rodado de pneus foi 7,1% menor em relação ao skidder de pneus recobertos por esteiras, o que explicado se pela maior eficiência dos pneus sobre a superfície do terreno. O skidder de pneus apresentou melhor eficiência na situação de declividade entre 10 e 20%, devido à maior agilidade do rodado de pneus e capacidade em desenvolver maior velocidade, enquanto o skidder com rodado de pneus recoberto por esteiras apresentou velocidade operacional constante. Em declividade acima de 20%, o skidder de pneus recoberto com esteiras realizou normalmente o arraste da madeira, enquanto o skidder de pneus não entrou em operação devido à elevada patinagem dos pneus e diminuição da capacidade de tração.The objective of this study was to evaluate technical log extraction activities using a skidder with tires and a skidder with tracks over the tires. Technical evaluation consisted in determining log extraction productivity indexes based on motion and time study, in which the extraction activities were grouped into work cycle phases. Machine productivity was determined in different extraction distances and slope degree situations. The results showed that the operational cycle average time of the tire skidder was 7.1% smaller that the skidder with tracks over the tires, explained by the efficiency of the tires over terrain surface. In slopes above 20.0%, the skidder with tracks over the tires performed the log extraction activities normally, while the tire skidder was unable to operate due to high tire skid and traction capacity decrease.

The applied skidding technology strongly influences the impact of harvest on the ecosystem and success of natural regeneration. The impact of skidder SLKT 81 and high-lead system Larix 3T on forest soil and natural regeneration was compared under analogical site and stand conditions in a production beech forest in the environs of Brno, Czech Republic. The skidder was found to have greater effects on the soil surface consistency, soil properties and natural regeneration than the high-lead system operations. Although high-lead system operations are more friendly to all parts of forest ecosystem, the skidder may not cause excessive damage when applied under suitable terrain and climatic conditions.