Evaluation of operator vibration exposure to chainsaws equipped with a Kesper safety bar

Abstract

Chainsaws are widely used for timber harvesting operations. Vibration transmitted into the operator's hand and arm system by the chainsaw's handle can cause vascular and neurological disorders. This article presents the results of operator vibration exposure to three different chainsaws, equipped once with conventional and once with Kesper safety bar. Measurements were done simultaneously on saws' front and rear handle, both for sharpened and blunt chain, as well as for three operational modes being cutting, limbing, and idling. Measurement and analysis of vibration were carried out according to the guidelines of ISO 5349-1 and ISO 5349-2. The results show that root mean square (rms) vibration acceleration was highest in the x-axis for front (in the vertical direction relative to the chainsaw – up though the hand) and in the z-axis for rear handle (perpendicular to the grip, up through the hand into the arm), respectively. For all measurements, vibration at the rear handle exceeded that of the front handle. Differences in vibration between saws equipped either with Kesper safety bar or with a conventional bar were not statistically significant. Frequency-weighted vibration (values for sharpened chain) for cutting was between 4.39 and 4.96 m/s². During delimbing values between 4.93 and 5.04 m/s² were recorded. Vibration for idling saw ranged from 5.87 to 6.15 m/s².

Keywords:

• Chainsaw
• hand-arm vibration
• Kesper safety bar
• vibration