Speaker
Description
Working conditions in forests are changing mainly due to the current state of forests as a result of climate change. More deadwood and pre-damaged wood are being felled, and there is more deadwood, especially in the crowns of the deciduous trees to be felled. As the risk increases, so does the potential danger of accidents. The results of the KWF accident statistics (https://unfallzahlen.kwf-online.de) show that there is an increased risk of accidents when felling trees manually with a chainsaw within a 5 m radius of the tree. For this reason, mechanical felling wedges are required to fell the tree manually from a safe distance with reduced risk.
The KWF e.V. is aware of the current state of knowledge in this area through previous research work and exchanges with partners in the field.
A basic data analysis was carried out as part of a bachelor's and master's thesis by Mark-Fabian Franz in 2020 and 2023. The topics covered were the required lifting forces and distances for different tree lean angles and for different hinge (height and width). One result was the creation and development of an online calculator to determine the required lifting force for a hanging tree. (https://hubkraftkalkulator.kwf-online.de/)
Furthermore, findings on the changing lifting forces and distances with changing dimensions of the hinge (height and width) were recorded.
The resulting knowledge about the interactions between tree species and tree condition as well as lifting force and distance can be used to optimize the selection of tools, reduce misjudgments and thus significantly increase occupational safety.
The development and application of the measurement methodology for lifting force measurement also took place in this work. Current literature on further studies reviewed and analyzed within this work. Furthermore, practical partners, manufacturer contacts and interviews with practical partners as well as literature from past decades are available to take into account the development of break bar geometries.
However, further necessary measurements and comparisons with practice are still lacking. The determination of lifting force has been published internationally on several occasions. It is necessary to investigate which measurement methods were used in each case. Furthermore, the differences between the various measurement methods used in terms of results should be explained.
A meta-analysis is currently being prepared on this topic in order to compare the measurements taken. The research question is: ‘How can the current state of knowledge about lifting forces and distances be further developed and the measurement methods improved?’
Another point is the consideration of the lifting force required for tree felling with a lifting cylinder compared to the lifting force required for tree felling using a technical felling wedge. The hypothesis here is that there is a slight difference in the lifting force required for tree felling using a lifting cylinder compared to that required using a felling wedge. However, this will be irrelevant in practice due to the necessary safety margin.
| Keywords | Chainsaw-Work; Tree-Felling; Lifting-Forces; Wedges |
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