Effect of Log Length on Forestry Loading and Unloading (original) (raw)
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Predicting productivity of timber loading operations: a literature review
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Loading is considered a bottleneck of the forest harvesting system as it acts as a connection between primary transport and secondary transport (from roadside/ landing to mills or central yards). Any delay during the loading component can cause delay in the primary wood extraction and/ or secondary transportation. This article reviewed the current knowledge on loading productivity studies. Based on the results, the main variables impacting the loading productivity include log size, log lengths, load volume per truck, number of logs (or pieces) per truck and number of safety straps. The productivity of loading operations ranged from 3.4 m3/PMH0 in a manual loading to 168.9 m3/PMH0 using mechanised loaders. The results of this review can assist the academic and industrial users for predicting, controlling and managing the productivity of loading operations.
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This research was conducted in wood harvesting and transportation areas in the mountainous region of Espírito Santo, Brazil, aiming to analyze the road transportation of forestry wood operations with self-loading trucks. The study identified and evaluated the times, average speed, mechanical availability, level of use and operating efficiency of three different designs of self-loading trucks. According to the results, there was no statistical difference between the vehicles regarding average speed. The highest mechanical availability was found in truck A (93.2%), followed by B (84.3%) and C (79.8%). The greater degree of utilization was found in truck B (91.8%), with little variation between vehicles C (90.0%) and A (89.9%). The highest operating efficiency was observed in truck A (83.9%), followed by B (77.4%) and C (71.8%). We concluded that self-loading truck A was the most efficient.
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The effects of certain operational variables on working time and skidder productivity in wood extraction in Eucalyptus grandis stands were investigated in this research. The study was conducted at a forestry plantation located in the municipality of Telêmaco Borba, Paraná State. Through a time and motion study the operational cycle time, mechanical availability, operational efficiency and productivity in relation to the variables volume, cycle time and extraction distance were quantified. The data were analyzed using Tukey's test at 5% probability and then fitted to a statistical model to explain the behavior of the variables in terms of machine productivity. Results showed that the time consumed by the empty and loaded travel phases was 20.4 and 45.0% of the total operational cycle time, respectively. Extraction distance directly affected the elements of operational cycle time and machine productivity, making it an important variable to consider in operational planning. The independent variables used explained around 82% of the skidder productivity variation, with the proposed model being suitable for use in wood extraction under similar conditions.
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This study aimed to perform an ergonomic evaluation of the timber manual loading activity on rural properties, in order to quantify the risk of development of musculoskeletal injuries in the forestry workers and, from the standpoint of ergonomics, identify the existence of the labor precarious conditions. Data were collected in small forest properties, located in Minas Gerais, and 28 forest workers were sampled. For evaluation, the 3DSSPP TM software, from the University of Michigan, was used. The results showed that there is a great and imminent risk to the health of workers during the manual loading of short logs, regardless of the phase of the activity, outstanding the risk of injury to the joints of the upper limbs (wrists and shoulders), as well as the trunk and coxofemorals. The resulting injury risks, whatever the mass of the handled short logs is, are due to the combination of posture and handled load factors, generating compression forces on the L5-S1 disc of the vertebral column that can be six times greater than the recommended limit value. Thus, under an ergonomic approach, the activity is being developed in an extremely precarious manner, with consequent early professional disability and decreasing work life of the workers.
Effect of Wood Stacking on Productivity and Cost of Forest Extraction and Loading
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Due to the need to implement new operational procedures that provide productivity gains and cost reduction in wood harvesting and logistics, the objective of this study was to evaluate the effect of wood stacking on productivity and costs of forest extraction and loading operations. The study was carried out in eucalyptus plantations, where the extraction of wood with the forwarder and the loading of vehicles with the forest loader were evaluated. Three log stacking models on the edge of the stand were evaluated: control, inverted and adjacent, with variations in the alignment and distance of the logs concerning the edge of the stand. A study of the times and movements of the operations was carried out, determining the productivity (m³.h-1) and the production cost (R$.m-3) of the forestry operations. The data were compared using the Tukey test (α=5%) for parametric data and the Kruskal-Wallis test (α=5%) for non-parametric data, and the effect of different extraction distances was a...
Effects of Timber Loads on Gross Vehicle Weight
Folia Forestalia Polonica, Seria A - Forestry, 2000
Forest roads are characterized by low traffic, but heavy timber haulage trucks have a significant influence on road conditions and usually exceed the limit of 80-100 kN per axle. The excessive weight of the trucks degrades the road surface and the forest environment. This article presents the results of a study of timber transport loads from their places of acquirement (forest districts) to the recipient (a large sawmill). The analysis includes the parameters of the timber transport vehicles and focuses especially on the gross vehicle weight (GVW), the total weight of empty truck and trailer during transport, and the weight of their loads. Scania, Iveco, Man, and Mercedes trucks with trailers and semitrailers designed for large-size pine timber transport were analyzed. ANOVA results revealed that all 80 analyzed vehicles exceeded the permitted GVW in the range from 2.28 to 19.94 Mg, transporting from 20.1 to 37.5 m 3 of timber. The coefficient of determination between the amount of hauled timber and the GVW equaled 62.7%. Research conducted previously concluded that forest roads with ground and gravel surfaces are not suitable for overloads of 120-150 kN per axle. Therefore, it is necessary to find a logistical solution that will allow the load volume to be maintained at an acceptable level without destroying the forest road surface.
LOG HAULING PRODUCTIVITY IN TIMBER HARVESTING OPERATION IN PENINSULAR MALAYSIA FOREST
NORIZAH K, MOHD-HASMADI I, HUSNA S & CHUNG W. 2016. Log hauling productivity in timber harvesting operation in Peninsular Malaysia forest. The study continuously recorded working elements and log hauling activities of log trucks. The variables measured were travel distance, number of logs and log volume which were regressed with hauling time and productive machine hour (m 3 PMH-1) using stepwise method via data analysis in Excel. Travel distance and the number of logs hauled per truck were found to be significantly corelated with hauling time, while all the three variables were significantly corelated with productivity. The equation models for both hauling time and productivity were developed using significantly tested variables. On average, productivity of free delay time of log hauling at the study area was 8.36 ± 2.49 m 3 PMH-1 and the operation cost of log truck was RM25.08. Thus, the unit cost of log hauling activities was estimated at RM3.80 m-3. The developed prediction model of hauling time, productivity and cost analysis could be used to plan timber harvesting activities with improved productivity and decreased cost.
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When transporting timber, the high variability of species, assortments and moisture content of the wood raw material does not allow the weight of the transported timber to be precisely determined. This often contributes to the excessive weight loading of the entire truck unit. The aim of the research is to present the variability of the total weight of truck units with wood cargoes (GVW-gross vehicle weight) depending on the weight of the empty unit and the transported timber load, as well as to analyze the changes in GVW, unit loads of wood and load on individual truck unit axles depending on the season. This study analyzes the total weight of truck units for 376 transports of Scots pine timber at different times of the year. The total weight of the truck units depends on the weight of an empty unit and the weight of the load. GVW was determined by using a weighbridge to weigh the vehicles and then the empty unit after unloading. The weight of the load was obtained as the difference between GVW and the tare. It was found that GVW differed significantly depending on the truck unit used, ranging from 43.60-58.80 Mg, often exceeding permissible limits for public roads. The individual axle loads for various truck units were also analyzed. The obtained results indicate that these loads are more equally distributed in the case of five-axle trucks compared to six-axle ones.
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Transport of wood biomass is one of the key operations in forestry and in the wood industry. An important part is the transport of shredded wood, where the most common forms are chips and sawdust. The aim of the research was to present the variability of the total weight of trucks (gross vehicle weight, GVW), the weight of the empty trucks (tare), and loads of chips and sawdust in different periods of the year. Changes in specific parameters were analyzed: GVW; tare weight; trailer capacity; use of the trailer load capacity; bulk volume and bulk density of wood biomass loads; solid cubic meter (m3) and weight of 1m3 of the load; and load weight depending on the season, with simultaneous measurements of wood chips and sawdust moisture. More than 250 transports from four seasons of the year were analyzed in the research. It was found that the total weight of trucks (GVW) was at a comparable level, on average from 39.42 to 39.64 Mg with slight differences (with SD 0.29 and 0.39). The w...
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This study analyzed the variability of truckloads of large-sized pine logs transported to a furniture manufacturing mill, depending on the origin of the timber, delivery period, length of the transported logs, volume of the load and its mass. It was assumed that the volume and mass of the transported timber load depends on the season of the year and the origin of the timber, which has a significant impact on the mass of one cubic meter of the load. The analysis of the wood origin parameters (location of its growth) took into account the type of forest habitat, soil type and stand abundance. The characteristics of the tree parameters from which the roundwood was obtained took into account age, diameter at breast height (DBH) and height of the stand. The origin of the timber was determined for 1063 timber loads from 40 forest districts transported over a 12 month period. We obtained an average timber load volume of 29.34 m3 which includes single shipments differing significantly in th...