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Struktura rocznego czasu pracy lesniczych

100%
Sylwan
|
2007
|
tom 151
|
nr 01
3-10
3
75%
The aim of the study is to characterise the working time structure of an operator of the LKT 82 skidder performing timber skidding on the sloping area, and to develop models of efficiency and time−consumption of the work depending on selected factors characteristic of the described transport process. The research was performed in the Sucha Forest District (S Poland). We considered two treatments: late thinning and felling performed in stands with the dominating share of beech. Logs obtained with chainsaws were initially extracted with horses and laid at the slope road. Later on the additional skidding with skidder tractor was done. Continuous timing of individual operations was performed with the use of a microcomputer equipped with time measurement software (accuracy of 1 second). We also determined skidding distance using a GPS device, the number of extracted logs in the load, and the volume of the logs. The total timing measurements lasted for a total of 70 h 24 min 27 s. During that time, the tractor made 72 cycles, transporting 998 logs with a total volume of 493.3 m³. In the mature stand, the average skidding distance amounted to approximately 1,160 m, a single load consisted of 3−4 logs with a volume of 7.7 m³. The operational efficiency of the skidding was 9.1 m³/h. In the thinning stand, the skidding distance was 1,230 m, the average load consisted of 22 logs with a volume of 5.8 m³. The operational efficiency amounted to 7.8 m³/h, on average. The working time structure was dominated by auxiliary (over 60%) and effective (nearly 30%) times. The obtained regression models of the duration of activities from the group of operational times were characterised by high correlation coefficient (about 0.75 for skidding time and driving without a load). Relatively strong relationships (r > 0.5) were also found between the times of collecting cable pulling and load attachment, and the volume of the extracted loads, and in the case of the times of collecting cable pulling also the type of treatment performed. The regression models for the times of log stacking, pulling the loads up with the winch and detaching them, despite the fact that they were statistically significant, characterised by relatively low correlation coefficients. The relationship between skidding efficiency and skidding distance was also determined (fig.). The duration of skidding cycles was described using the multiple regression with the volume of single loads and the skidding distance as the determinants. The regression models of skidding efficiency and time−consumption of skidding cycles may find practical application in estimating the efficiency of the tasks performed in stands and under conditions similar to those analysed in the present research.
The aim of the study was to recognize the annual worktime structure and the actual number of working hours at the forester and deputy forester workstations in the State Forests. The research was carried out on the sample group of 462 workers in all regional directorates of the State Forests in 62 forest districts and 242 forest ranges. The study group consisted of 21 (4.5%) forest foresters from one−man forest districts (L1), 222 (48.1%) foresters and 219 deputy foresters (47.4%) from two−men forest ranges (L2 and PDL respectively). Altogether 17 groups of activities were distinguished. The workers were studied in spring, summer, autumn, and winter. Every time the research was conducted during one full week (Monday−Sunday). In case of two−men forest districts, both workers were studied simultaneously. The measurement of timework was carried out with the specially designed mobile application LP1 operating in Android system. The duration of particular activities at L1 and L2 workstations was similar. The office work constituted most of their worktime: 109.7 minutes (22.9%) for L1 and 111.5 min (23.3%) for L2. Transportation took 80.2 and 84.8 min (17.7 and 17.6%), whereas wood sale required 69.7 and 62.8 min (14.5 and 13.1%) for L1 and L2 work stations respectively. At PDL workstation passages took 84.7 min (17.6%), wood quality inspection and registration – 65.4 min (13.6%), and office work – 60 min (12.5%). The tasks comprising preparation, harvesting and sale of raw timber took 34.9% of L1 worktime, 32.5% in case of L2 and 41.6% for PDL’s worktime. All employees devoted the least of their worktime to tasks connected with fire precautions, nature conservation, and environmental education (tab. 1). The overrunning of normative worktime was recorded at all studied workstations. The mean daily worktime for PDL amounted to 8.17 hrs, whereas for L1 and L2 it was 8.47 and 8.52 hrs respectively. Except extra working hours during the working week, the overtime during the days−off was recorded too. Most of time spent on work in such situations was recorded for L1 (1.69 hrs on average per week), while the least (0.97 hrs) for L2 workstation.
Skidders are used at two stages of log extraction: when pulling logs to a skid trail and for further semi−suspended log skidding along the trail to a landing. The aim of the study is to characterise the working time structure of a skidder operator performing timber extraction from the stand to the trail, and to develop time−consumption models depending on terrain slope and skidding distance. The research was done in stands situated in central and southern Poland, where late thinning and cutting in areas between tree groups (group clear cut) were performed. The timber was transported to skid trails by means of LKT 82 cable skidders. The timber was pulled to the trail on slopes with inclinations ranging from –30° (up the slope) via 0° (on a flat surface) to 38° (down the slope) at a maximum distance of 70 m. Time study of work cycles was performed and the volume of timber harvested in each package was calculated. Analyses of working time and its time consumption were performed for the operational working time. The measurements covered a total of 269 log extraction cycles with a total duration of over 20 hours. Altogether 752 logs with a total volume of over 520 m³ were extracted. The large share of time was devoted to load attaching and detaching (40%). Quite a large share of log extraction (24%) was associated with the long skidding distances. The time of stretching the collecting rope in the case of skidding up the slope (an average of 60 s) was significantly shorter than in the flat terrain or skidding down the slope (70 s). The average duration of a skidding cycle was also affected by the direction of the slope. Rectilinear relationships were determined between the duration of a skidding cycle and the terrain slope, as well as the skidding distance. The combined effect of these features on the duration of skidding was described. The duration of a skidding cycle was influenced by distance (61% of the general variability) more than the slope (16%). The time consumption of the skidding amounted to ca 12 min/m³. Two homogeneous groups were determined: uphill skidding as well as skidding in flat terrain and downhill. The relationship between the time consumption and the number of logs extracted along with their volume took the form of an exponential regression. The time consumption standard of log extraction performed with the use of a skidder along a skid trail should be supplemented with the time of forming timber packages in the stand and pulling them to the trail, with an additional distinction between the direction of skidding and terrain slope.
Natural disasters often cause that large share of acquisitions are performed under contingent conditions. High concentration of raw wood material and urgent need for its rapid removal from the forest demand use of harvesters. Material acquisition in such conditions is much harder and causes loss of performance for working machines. The objective of this paper was to determine the decrease in harvester performance during acquisition of fallen trees, wood scrap and suspended trees compared to acquisition of undamaged trees. Performance analysis was conducted on 10 harvesters from different power class working in the Czech Republic in years 2007−2012. The time structure was determined for the timber acquisition under contingent conditions in 22 forest stands. Later on it was compared with acquisition under normal conditions, i.e. scheduled acquisition on areas with good load carrying capacity and without obstacles and with an inclination up to 33%. There was significant difference in the mean operating time requirements between harvesters from the analysed power classes. Machines form 1st class differed significantly form devices from 2nd and 3rd classed. Results indicate that in spruce stands with wood scrap time consumption increases by 7% when average and high performance harvesters are used. The increase is by 33% during acquisition of fallen trees, while time consumption increases by as much as 79% during acquisition of suspended trees. During acquisition of subversion and wood scrap, performance of average and high performance harvesters ranged between 1.71 up to 17.37 m3/h depending on thickness and type of the damage to obtained trees. Important achievement of presented research is correction factors allowing to change harvester performance standards, while acquisition of fallen trees, wood scrap and suspended trees. Average value of correction factor is 1.19.
11
63%
Sylwan
|
2010
|
tom 154
|
nr 01
52-63
The amount of timber extracted from Polish forests is expected to increase in near future. The most common equipment for timber extraction is an agricultural tractor with a trailer equipped with a hydraulic crane. The research was carried out in the Wymiarki Forest District (Regional Directorate of the State Forests in Zielona Góra) in the third (TP1) and fourth age class (TP2) in Scots pine stands, during extraction of timber from thinning. Extraction was carried out using BELARUS MTZ 1221.2 agricultural tractor with PALMS 120 forest trailer equipped with PALMS 700 hydraulic crane. The scope of the study was to conduct time studies of extraction process and to estimate the extraction productivity as well as time and fuel consumption. Working time was measured by stopwatch, while the forwarding distance was determined with measuring wheel. The exact number of logs in each load was established. Average volume of each log and each load was calculated. The dominant work time category was effective working time 74.78% (TP1) and 73.60% (TP2), while the prevailing work task was loading 56.82% (TP1) and 58.99% (TP2). In older stands, the extraction productivity was higher than in younger ones reaching 11.28 and 9.62 m³/h, respectively. Statistical analysis proved that extraction distance significantly affect productivity and time consumption. With increasing extraction distance productivity decreases and time consumption increases. Fuel consumption was exactly the same in younger and older stands (0.52 l/m³).
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