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EN
Holding determined body postures during work is connected with energy expenditure. The more forced the posture is, the more muscles take active part in holding and stabilizing the working posture. In forest operations the most share of awkward (forced) working postures occur during the tree felling with a chainsaw. It is also one of the hardest activities in motor−manual timber harvesting process. The group of 10 experienced fellers in the age of 47.5±7.3 years was studied. The research was carried out on four Scots pine clear−cuts in western Poland, in spring and autumn without snow cover. The average air temperature was 7.1±4.8°C, and humidity amounted to 72±6.7%. In the simulation study the fellers cut thin wood slices from 30 cm stumps. The stumps were located close to each other in order to minimize the influence of passes from one to another. The diameter of stumps was selected so that it wouldn't exceed the effective length of the chainsaw bar. The felling was carried out with the chainsaw Stihl MS 361 with the power of 3.4 kW and weight of 7.5 kg. Net energy expenditure (NEE) was determined using the pulmonary ventilation measurement (MWE−1 meter) during simulation of felling in 4 working postures (fig.). The lowest energy expenditure was observed for kneeling down on one knee and squatting: 16.4 and 16.9 kJ/min, respectively. Standing bent forward working postures feature statistically higher energy expenditure, reaching 19.9 kJ/min with straight legs and 22.1 kJ/min with bent legs (p<0.05). The realized research confirmed that body posture during felling with a chainsaw influences the level of the feller's physical workload. Standing bent postures cause energy consumption which is higher than during squatting and kneeling on one knee. The most preferred working posture, from the point of view of energy expenditure and biomechanical workload during felling, is standing bent posture with straight legs. The other postures, especially squatting, can be used regularly for a short time in order to unburden a lumbar part of spine. Applying working postures that require less energy during felling with the chainsaw may contribute to reducing the work heaviness on the feller's workstation.
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EN
The work of woodcutter is considered to be hard and dangerous. This job requires not only knowledge, but also skills. Experience is considered one of the most important factors affecting the safety of the chain saw operations. The objective of the study was to analyse the effect of experience on the performance of woodcutters. The research was carried out in Chojnów Forest District (central Poland) and included three woodcutters with different level of experience: A – inexperienced person (1.5 years of work), B – average experience (15 years of work), C – extensive experience (22 years of work). We analyzed the quality of the felling operations carried out in a Scots pine stand studying the following parameters: width of the hinge, height of the safety threshold and height of the stump. Woodcutter A made a lot of mistakes and his work was characterized by the high risk of an accident. Woodcutters B and C seem to have worked safer, but woodcutter C in most cases did not leave the safety threshold of the required height. The decisive factor in safety has been and will remain the quality of the lumberjacks training and enforcing it during professional examinations. High quality of trainings is of crucial importance, especially for less experienced woodcutters.
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