Wood Density Impact on Hand-Arm Vibration

Nacrtak Despite technological advancements in machinery for timber harvesting, chainsaws are fre­ quently used in forest operations. In Austria 85% of the wood volume harvested (15 million m3) are cut by chainsaws. The two most frequently documented ergonomic threats during motor manual felling include exposure to noise and vibration. This paper presents the results of exposure to hand-arm vibration with focus on the impact of different density of wood species. Vibration exposure during crosscutting of Black poplar (oven-dry density of 400 kg/m3), Norway spruce (oven-dry density of 360 kg/m3) and European beech (oven-dry density of 700 kg/m3) was measured on three Husqvarna chainsaw models differing in size and power output. Measure­ ment and analysis of vibration were carried out in accordance with guidelines of ISO 5349-1 and ISO 5349-2. The results show that total values of unweighted root mean square (rms) vibration acceleration do not differ between tree species. Anyway, frequency-response curve of beech differed from that of poplar and spruce. Applying the weighting filter of ISO 5349-1, the frequency-weighted vibration of beech had higher values than those of poplar and spruce. No significant differences were found between poplar and spruce. Vibration values (measured on chainsaw rear handle) ranged from 4.06 m/s2 to 4.92 m/s2 for poplar, 4.38 m/s2 to 5.66 m/s2 for spruce, and 5.84 m/s2 to 7.38 m/s2 for beech, respectively.