Innovative productivity improvements in forest operations: a comparative study of the Assortment Grapple using a machine simulator

Manner J., Berg S., Englund M., Ersson B.T., Mörk A. (2020): Innovative productivity improvements in forest operations: a comparative study of the Assortment Grapple using a machine simulator. J. For. Sci, 66: 443–451.

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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.

Björheden R. (2001): Learning curves in tree section hauling in central Sweden. Journal of Forest Engineering, 12: 9–17.
Björheden R., Thompson M. (2000): An international nomenclature for forest work study. In: Field D.B. (ed.): Proceedings of IUFRO 1995 S3. 04 Subject Area: 20th World Congress; Tampere, Finland. Orono, Maine: University of Maine, Aug 6–12, 1995: 190–215.
Brunberg T., Lundström H. (2016): Tidsåtgång och bränsleåtgång vid användning av sortimentsgripen 2014. [Evaluation of assortment grapple 2014 in terms of processing time and fuel consumption]. Arbetsrapport nr. 909-2016. Uppsala, Skogforsk: 5. (in Swedish with English summary)
Dvořák J., Natov P., Natovová L., Krilek J., Kováč J. (2016): Operator’s physical workload in simulated logging and timber bucking by harvester. Journal of Forest Science, 62: 236–244.
Gullberg T. (1997): A deductive time consumption model for loading shortwood. Journal of Forest Engineering, 8: 35–44.
Häggström C., Öhman M., Burström L., Nordfjell T., Lindroos O. (2016): Vibration exposure in forwarder work: effects of work element and grapple type. Croatian Journal of Forest Engineering, 37: 107–118.
Kaleja S., Petaja G., Zimelis A., Puzuls K. (2018): Increase of forwarding productivity and reduction of tree damages in thinning by use of loading grapple with tilt function. In: Malinovska L., Osadcuks V. (ed.): Proceedings of the 17th Engineering for Rural Development, Jelgava, May 23–25, 2018: 1384–1389.
Kellogg L.D., Bettinger P. (1994): Thinning productivity and cost for mechanized cut-to-length system in the Northwest Pacific coast region of the USA. Journal of Forest Engineering, 5: 43–52.
Manner J., Nordfjell T., Lindroos O. (2013): Effects of the number of assortments and log concentration on time consumption for forwarding. Silva Fennica, 47: 1–19.
Mörk A., Englund M., Brunberg T. (2017): Utvärdering av sortimentsgripen i simulator. [Evaluation of assortment grapple tested in a simulator]. Arbetsrapport nr. 924-2017, Uppsala, Skogforsk: 13. (in Swedish with English summary)
Nurminen T., Korpunen H., Uusitalo J. (2006): Time consumption analysis of the mechanized cut-to-length harvesting system. Silva Fennica, 40: 335–363.
Ovaskainen H. (2005): Comparison of harvester work in forest and simulator environments. Silva Fennica, 39: 89–101.
Ovaskainen H., Palander T., Tikkanen L., Hirvonen H., Ronkainen P. (2011): Productivity of different working techniques in thinning and clear cutting in a harvester simulator. Baltic Forestry, 17: 288–298.
Petaja G., Kaleja S., Zimelis A., Lazdins A. (2018): Comparison of productivity of standard and accumulating forwarder grapple in thinning. In: Malinovska L., Osadcuks V. (eds): Proceedings of the 17th Engineering for Rural Development, Jelgava, May 23–25, 2018: 1366–1371.
Piepho H.P., Edmondson R.N. (2018): A tutorial on the statistical analysis of factorial experiments with qualitative and quantitative treatment factor levels. Journal of Agronomy and Crop Science, 204: 429–455.
Searle S.R., Speed F.M., Milliken G.A. (1980): Population marginal means in the linear model: an alternative to least squares means. The American Statistician, 34: 216–221.
Sirén M., Aaltio H. (2003): Productivity and costs of thinning harvesters and harvester-forwarders. International Journal of Forest Engineering, 14: 39–48.
Strandgard M., Mitchell R., Acuna M. (2017): Time consumption and productivity of a forwarder operating on a slope in a cut-to-length harvest system in a Pinus radiata D. Don pine plantation. Journal of Forest Science, 63: 324–330.
Väätäinen K., Ala-Fossi A., Nuutinen Y., Röser D. (2006): The effect of single grip harvester’s log bunching on forwarder efficiency. Baltic Forestry, 12: 64–69.
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