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Because of generally small log piles, loading forwarders during thinning is time consuming. The Assortment Grapple, an innovative grapple with an extra pair of claws which facilitates the handling of two assortments during one loading crane cycle, has been designed to decrease forwarders’ loading time consumption. A standardized experiment was performed in a virtual thinning stand using a machine simulator with the objectives to form guidelines for working with the Assortment Grapple and to analyse its development potential. Four experienced operators participated in the study. According to the results, the Assortment Grapple’s accumulating function is beneficial only when there are no remaining trees between piles loaded during the same crane cycle. In such cases, none of participating operators lost time, and 3 of 4 operators saved time notably. The problem with the remaining trees is the extra time required to steer the crane tip around them. Therefore, a harvester should place those log piles that are later to be forwarded together in the same space with no remaining trees between the piles. Furthermore, we recommend that the Assortment Grapple’s usability will be improved by adding an own rocker switch on the forwarder’s controls to command the extra claws.

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Swedish legislation stipulates the precision required for estimates of parameters used to determine the value of various forest fuels. The net energy value of fuel, as it is received, is often used to set the trade price. The estimate of energy content is based on the moisture content of samples taken from each truckload and the weight of the biomass; the ash content and net calorific value are measured a few times each year. Hence, it is necessary to know the variation in moisture content to ensure that a sufficient number of samples are taken, a number based on the allowed variation and precision of estimates, as defined in the legalization. In this study, the variation in moisture content was measured by taking samples from 18 truckloads of comminuted forest fuels during the winter. The results showed that the current sampling regime, i.e., manually taking four samples from each truckload, is sufficient for deliveries with 10 truckloads for logging residue chips and 4 for stem wood chips. The number of samples should be increased to 12–43, 8–21, and, 17–82 depending on assortment for what the measuring act defines as large deliveries (>=50 tonnes; >=3 truckloads), medium-sized deliveries (<50 – >25 tonnes; 2 truckloads) and single truck deliveries (<= 25 tonnes; 1 truckload), respectively. Current research into fast online sampling and analysis methods could resolve this issue for small deliveries.

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Automatic data collection is becoming increasingly common in cut-to-length forest operations. However, only few studies have analyzed automatically collected follow-up data from forwarders. In this study, we analyzed the driving distances of the four work elements Driving empty, Loading drive, Driving loaded, and Unloading drive (the sum of which being Total driven distance) of two forwarders operating in central Sweden. The analysis included finding the most appropriate probability density functions for each distance at the stand level (46 final felling stands in total, with one load as the unit of observation). The results showed that the mean intra-stand Total driven distance ranged 364–2393 m, and that most distances in the majority of the stands were positively skewed. Versatile probability distributions like Generalized Extreme Value and Log-logistic were the most common probability distributions. Our results provide researchers and managers a numeric understanding of the intra- and inter-stand variation of forwarding work. Hence, our study can help spread awareness of this variation to managers and foresters. With this awareness, managers, foresters, and researchers can better understand the pros and cons of follow-up data from forwarders, and how to best use and collect it. Our results can also be used by researchers as high-resolution indata during simulations of forwarding work. Additionally, the results can be used as a reference or control when determining the most suitable data distributions in future studies.