Coupling forces resulting from the type of chain saw used.

Introduction: Woodcutters' working conditions are difficult due to the presence of numerous occupational hazards. Petrol-fuelled chain saws commonly used in forestry produce vibration, which may lead to the development of non-specific disorders in the upper extremities of the chain saw operator, referred to as hand-arm vibration syndrome (HAVS). The magnitude of coupling forces exerted on a vibrating tool handle may affect the severity of HAVS and hand-wrist cumulative trauma disorders. The aim of the presented study was to measure coupling forces exerted by fellers on various chain saws and to find correlation between force magnitude and type of tool used.

Material And Methods: Coupling forces applied by workers on different types of chain saws were measured by means of a hydro-electronic force meter. All measurements were carried out during the harvesting of wood in real work conditions.

Results: Mean force applied by forestry workers on their tools was 44.2 N. Coupling forces registered during cutting wood with small universal chain saws were larger than forces exerted on models characterized by higher power profile. Forces applied on comparable tools produced by various manufacturers also differed.

Conclusions: The relationship between coupling forces and power of the chain saw should lead to ergonomic improvements of the tool and vibration-reducing devices. These results can also be used as a recommendation for fellers in a range of using proper machines for different types of cut or types of wood. They may also be applicable to develop more effective methods for assessing vibration exposure risks among woodcutters.