engleski

Productivity factors of Timberjack 1210 at forwarding the main felling roundwood in Croatian lowland forests

The paper shows the influence of some factors (extraction distance, harvesting density, dimensions of processed roundwood, conditions of soil strenght, sorting of assortments during unloading) on productivity of 12-tones forwarder Timberjack 1210 which worked on extracting of roundwood from regeneration fellings in Croatian lowland forests. Research was carried out on 5 workplaces at the period of 34 working days, when was extracted 3584 m3 of hardwood assortments (oak and ash) in 370 forwarder cycles. The common feature of forwarder operation at all the researched felling sites was extraction of only technical roundwood processed by cut-to-lenght method with chainsaws, and free movement of the forwarder across the surface of felling units during the loading of timber. The sorting of assortments at the landing during unloading occurred in case of several types of species or quality classes of roundwood in the forwarder load. The felling sites differed by: average extraction distances (240 to 610 m), off-road soil strenght conditions in the course of the research (from mud to dry or frozen soil), harvesting density of the processed technical roundwood (85 to 132 m3/ha) and the average quantity of the processed assortments: mid-diameter (23 to 51 cm), length (3.6 to 5.5 m), and volume (0.23 to 0.72 m3/pcs). The forwarder productivity was established by work and time study, and time consumptions of work components were measured by fly-back chronometry method. The productivity level of forwarders per researched felling areas was influenced by the complex effects of off-road soil strenght conditions, dimensions of roundwood processed by cut-to-lenght method, harvesting density, and sorting of assortments at the landing during the unloading. For diversity and disparity of influenced factors encompassed at the research sites, their influence on the productivity of forwarders’ operation was established indirectly, through the time consumptions of work components, and the achieved load features. The research established the following:  The load volume was under various influences of the key terrain factor of lowland forests – off-road soil strenght, as well as of the number of roundwood pieces of specific dimensions,  The travel speed of unloaded and loaded forwarder depends on the type of surface on which the vehicle moves (off-road soil strenght conditions, forest road with gravel layer in the landing area),  The time of work with crane at loading and unloading depends on the number of roundwood pieces of specific dimensions in the forwarder load,  The time of works without crane at loading is influenced by the felling density of technical roundwood intended to primary timber transport,  The time of works without crane at unloading depends on the need for timber sorting at the landing in case of occurrence of more types of species or quality classes of roundwood in the forwarder load,  The allowance time depends on off-road soil strenght conditions.

forwarder productivity; influencing factors; regeneration fellings; Croatian lowland forests

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