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ŠUMARSKI LIST 1-2/2020 str. 37     <-- 37 -->        PDF

Productivity of a farm tractor with single drum winch during whole-tree timber extraction
Proizvodnost adaptiranog poljoprivrednog traktora s jednobubanjskim vitlom tijekom privlačenja drva stablovnom metodom
Sercan Gulci
In forested areas with difficult terrain conditions the cost of forest harvesting operations is of great importance. This situation affects the technology standards of tools and equipment used in forestry operations. Especially in developing countries modified farm tractors are widely used as effective tools for transporting timber from stump to landing areas. In this study, productivity of the farm tractor with front-mounted single drum winch designed for multipurpose use in forestry operations was evaluated during whole-tree harvesting operation. The total cost of used system (tractor and winch) is approximately 19580 € (Euro). Time and motion study was implemented by using repetitive time measurement technique during two step timber extraction operation. The effects of main factors such as tree diameter, height, volume, and skidding distance on the total operation time were investigated and then linear regression analysis was performed to develop the mathematical models for whole-tree extraction methods. Time study data resulted that winching trees to the prebunching area was the most time consuming work stage in uphill winching method while skidding trees backward to landing was less time consuming work stage in skidding method. The average productivity of uphill winching and skidding whole-tree was as 12.98 m3/hour and 14.30 m3/hour, respectively. The cost of uphill winching and skidding was 10.77 €/hour and 11.87 €/hour, respectively. It can be concluded that the single-drum hydraulic system, which is mounted on the front of the tractor, can be used as an alternative harvesting equipment especially for uphill winching operations in small scale forestry operations.
Key words: Mountainous forests, forest harvesting, farm tractor, productivity, whole-tree method, developing countries
Since the 1960s, it has become progressively accepted that, for a sustainable management, several criteria have to be considered at the same time. The consequence is that the decision-makers need a suitable multi-criteria decision-making methodologies (Erler 2017). The use of forest resources and production of forest products vary according to the development level of the countries. This variation is primarily observed in planning and implementation of timber extraction methods due to relatively high proportion of economic benefits provided by wood-based forest products in forest industry. In some countries, forest products are being produced for a limited number of industrial uses by utilizing limited amount of mechanization involvement.