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ŠUMARSKI LIST 1-2/2020 str. 39     <-- 39 -->        PDF

studied in the timber extraction activities (Acar 2013). In some studies carried out in this context, it was determined that the skidding distance, slope, timber volume and number of logs are effective on the productivity of the farm tractor (Ozturk 2010). The additional equipment attached to the farm tractors for winching, forwarding or loading purposes may show different performances in terms of productivity of the system (Acar 1997). In recent years, examples of decision support systems have been developed in order to increase the productivity of the farm tractors in harvesting operations (Gumus and Turk 2016).
Modifications of farm tractors specially designed for forest operations have recently increased the attractiveness of farm tractors in the forest industry. There are considerable experiences in the use of farm tractors especially for small-scale forestry activities. As a result, the need to investigate the effectiveness and efficiency of the modified farm tractors has emerged in recent years. In this study, productivity of the farm tractor with front-mounted single drum winch was evaluated during whole-tree harvesting operation in Eastern Mediterranean region of Turkey.
Study area – Područje istraživanja
This study was carried out in Baskonus Forest Enterprise Chief (FEC) of Kahramanmaras Enterprise Directorate within the border of Kahramanmaras Regional Forest Directorate in Eastern Mediterranean region of Turkey (Figure 1). The dominant tree species in the region are black pine (Pinus nigra Arn.), Turkish red pine (Pinus brutia Ten.), firs (Abies cilicica Ant. et Kotschy) and cedars (Cedrus libani L.). The average elevation in the main study area ranges from 800 meters to 1170 meters. Time study data were collected during timber extraction of Turkish red pine trees in compartment 33 (GDF 2012). The ground slope at the uphill winching area ranged between 45% and 50% while the slope of skid trail was between 5% and 10% (Figure 1b and 1c).
Field study – Istraživanje na terenu
The geographic positional information was recorded by using a Global Positioning System (GPS). The topographical structure was determined by NRTK (Network Real Time Kinematic) Global Navigation Satellite System (GNSS)-GPS surveyed digital terrain model were evaluated by using GIS techniques for the sensitive determination of trails’ topographic attributes. Chronometers were used in time and work study. Besides, a digital camera was used to show the working area and the condition of the farm tractor during the winching and skidding stages. Total tree volume and cost information for stand compartment 33 was obtained from Kahramanmaras Regional Forest Directorate.
A four-wheel drive farm tractor equipped with 4-cylinder Turbo Intercooler system was used during timber extraction applications. The list price without taxes of operated farm tractor is approximately 17718 €. Main of mechanical and hydraulic properties of the tractor are shown in Table 1. The timber extraction operation was carried out by four forest villagers who were employed by a forestry development cooperative. Forest villagers stated that they had more than five years of experience in performing forestry operations.
Using whole-tree method, felled trees were transported uphill from stump to skid trail by using single drum winch mounted in front of a farm tractor and then they were skidded on the skid trail while tractor was moving backward to the landing area (Figure 2).
The winch system was reinforced by an iron frame in order to prevent damage to the farm tractor during timber extraction. The thickness of used the steel rope, was 14 mm. The maximum rope length capacity of drum was 80 m. Tractor was equipped with a front protection blade which can move up and down by hydraulic pressure for stability purposes. Joystick arm type controllers were placed next to the tractor operator in the cabin for manual control of the hydraulic system (i.e. winch and blade). The cost including iron frame, front protection blade apparatus and hydraulic system of designed single drum winch was 1860 €.