UThis 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 semitrailer, tractor reconstruction, type of semitrailer crane, load volume.
Tractors for tractor assemblies Formet are equiped with double-drum winches mounted on the rear part of the tractor and they increase the total mass of the tractor and the load of the rear axle.
Masses of the unloaded tractor assemblies are almost the same and they range around 8800 kg. Masses of unloaded semitrailers depend on semitrailer load capacity and on mounted hydraulic crane. Based on the measurement of the load at the hitch point of the tractor, it can be concluded that the mass of the crane is mostly transferred to the rear axle of the tractor. It can be further concluded that the distance between semitrailer wheels and the hitch point of the tractor results in the increase of the influence of the mass of hydraulic crane and mass of load on tractor load.
Masses of tractor assemblies with the load of 3.19 m³ (mean value of 3744 kg) range between 12505 kg and 12582 kg. Depending on the position of the semitrailer load, a certain part of the load mass will be transferred to the rear axle of the tractor. The results show that 4% to 15% of the total load mass is transferred to the rear axle of the tractor.
With the above load, measured loads of the tractor Belarus 920 and 952 in the tractor assembly „Formet“ reach the total permissible load of 7000 kg. However, as the load capacity of the semitrailer Metalac S-6, which is used in the tractor assembly Formet, is 6 tons, provided that the transfer ratio of the load mass through the hitch point is the same (approximately 10%), it can be estimated that the total permissible tractor load will be exceeded when the semitrailer is fully loaded.
Based on these investigations and past expertise, it can be generally concluded that tractor assemblies are not specialised forest vehicles and that they lack technical features required for performing wood extraction, because they are made by adapting and reconstructing farming tractors and forest semitrailers, which results in exceeding permissible axle loads.

Keywords: tractor assembly, mass, axle load, permissible load

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 Đurđevac). In this case the system was installed in the forwarder Valmet 840.2 together with a fuel consumption meter. The forwarder computer, which inputs data from the existing measurement converters provided with the forwarder, was also connected to the mobile unit of FM System. By GPRS connection, all obtained data were sent to the control centre, where the report is generated and sent further to the end user. The parameters measured in this research were as follows: coordinates of the forwarder position (forwarder travel), cumulative fuel consumption, number of engine revolutions, detection of crane operation and forwarder travel path. Apart from difficulties we had during the installation of the above said system, all research results are satisfactory except the coordinates of the forwarder position and the cause of this poor result lies in the fact that the GPS antenna was disconnected from the forwarder cabin so that additional protection must be provided in future.

In order to avoid problems related to the application of FMS presented in this paper, the manufacturer of forwarders offers the possibility of equipping the machine with its own measurement converters. Commercial FMS is installed subsequently in the forwarder equipped as described above and it is used for transmitting data by GPRS from the vehicle to the server, and the end user can access these data through a web interface.

Keywords: forwarder, Fleet Management System (FMS), measurement converters, GPS

This paper gives a survey of the development of the forwarder from its origin to the modern machine as used nowadays in timber extraction with the focus on some new characteristics that may facilitate the work and increase its productivity. Accessories installed in its forwarders by the manufacturer Valmet are also presented in this paper. Some of the above characteristics are highly desirable in Croatian forestry, and some of them are not primarily due to types of tree species of our forests and due to the type of our forest management.

The feature of LoadFlex system that provides the possibility of hydraulic height adjustment of side supports, thus lowering the path of the crane, would be best applied in our forestry. The system in which the bunk supports can be set in three positions could be applied in Croatian forestry for forwarding coniferous assortments or assortments of fast-growing broadleaved species, where wood assortments are smaller (diameter) or have a lower unit mass per piece. With the assortments of Pedunculate oak, which are usually large and also have a high unit mass, it is considered that the joints of the above supports would easily break down. In Croatian forestry forwarders are often used for forwarding assortments in thinning stands, then for forwarding assortments in salvage cuts, and of course also in the initial cuts of regeneration felling (preparatory and seeding felling) where the density of the remaining trees in the stand is usually high so that a forwarder equipped with LoadFlex system with support arms set to the widest position would have serious problems in moving around.

LoadFlex Bio option is very simple and in our forestry it would have the most important role in forwarding forest residues consisting of branches of non-coniferous species as well as of fuel wood of a size usually too small to be fastened between bunk supports. Such solution may be mounted on forwarders equipped with a standard bunk with simple support arms thus greatly facilitating forwarding of the above mentioned forest residues as well as residues made of branches of coniferous species that are usually of small size.

ProTec system of controlled installation of hydraulic hoses is a useful solution and it is considered that this option should be installed immediately upon buying the forwarder. This system reduces swinging of grapple arms and at the same time considerably facilitates operating the crane and consequently also accelerates loading and unloading of wood assortments.

Scaling by MaxiScale system is probably not fully satisfactory (Fig. 9) because the forest residue does not only rely on the construction of the load area but also on the soil behind the forwarder, and therefore a portable scale system would be a more favorable solution.

Keywords: forwarder, historical development, accessories

Excluding the former SSSR, most of the forests in Europe are private. However, up to now there have been no comprehensive data bases about them. Models of private forest management vary significantly, depending on the relative share of private forests, their ownership structure, development progress of the sector and its share in the GDP. This paper provides an overview of private forests in Croatia, South-Eastern Europe and in the entire Euro¬pe, as well as a depiction of trends in their management, with the analysis of the influence of those trends on the ma¬nagement of private forests in Croatia. Relevant studies predict a growth of demand for timber above the level of an¬nual allowable cut in Europe. Considering the fact that in most European countries private forests are managed wi¬th a lower intensity than state owned forests, it is expected that the difference between the projected timber demand and supply will probably be compensated by bringing the annual allowable cut in private forests close to the level of their increment, by intensifying silvicultural operations and by applying economies of scale in logging activities. In order to do so, private forest owners should join into associations that act at the level of operational forest management.

Keywords: private forests, timber mobilization, sustainable management, private forest owners associations

This paper shows recent developments in the area of entrepreneurship in European forestry. An overview of experiences and status of forestry entrepreneurship within countries of Central and Eastern Europe covers their characteristics, as well as the characteristics of their associations, including their features such as outlines of their work, training and traineeship programs, state of safety and health protection, facilities and limitations in providing forestry services, etc. Insight in the specified aspects of entrepreneurship is a valuable contribution to state knowledge in performing forestry work in Europe. Remote models and experiences in their application are a significant factor in improving private forestry work performance, as well as a valuable base for the improvement of entrepreneurship in Croatian forestry. As an example of developed entrepreneurship we have elaborated private forestry sector and forestry companies in Germany and Finland. Examples of poor conditions of forestry entrepreneurship were presented through an overview of the situation in countries with less developed forestry – Poland, Bulgaria and Latvia.

Keywords: forestry, forestry operations, forestry contractors, entrepreneurship, Europe

This article deals with forest management as a sector of national economy, whose main aim is the holistic and sustainable management of forests in Slovakia and their further development. The article discusses the issue of the current situation in forests and forestry in Slovakia, not only from the aspect of the extent of forest land and forest stands, but also from the aspect of tree species composition, timber felling and logging, forest opening up by forest roads, application of technologies in forestry, principles of timber felling and the resulting obligations for the staff responsible for the keeping of ecological principles.

Keywords: forest, forest management, timber felling, growing stock

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