Measuring the vibration of a brush cutter in different operation modes

Extended exposures of the hand and fingers to vibration can result various disorders like finger blanching, numbness at the hand, tingling, reduced muscle activity or bone and joints problems (Griffin, 1990). The source of hand-transmitted vibration is often a hand-held tool that is widely used in gardening or landscape architecture. Vibration induced injuries at the hand-arm system, have been widely studied among forestry workers using chain saws (Sutinen et al., 2006; Färkkilä et al., 1988; Bovenzi, 2008). The operators of hand-held power tools are exposed various levels of hand-arm vibration at the tool-hand interface. Risks can be assessed either without performing measurements, by referring to information available from manufacturers or certified databases, or by means of measurements carried out in accordance with methodology defined in specific ISO-EN standards. The EU Physical Agents Directive on human exposure to vibration published on 22 June 2002, defines ‘‘the minimum health and safety requirements’’ for the exposure of workers to the risks arising from vibration. The Directive sets two limits for hand-transmitted vibration: the exposure action value is 2.5 ms and the exposure limit value is 5.0 ms (Directive 2002/44/EC). The acceleration values for hand held tools such as brush cutters have been measured at the handle of a tool according to ISO 5349:2001 in order to evaluate their vibration. Several factors might contribute to the vibration transmitted to the hand like operator’s posture, working conditions, individual factors, etc. (ISO 5349:2001). It is therefore important to determine the standardised working conditions in which the measurement is carried out. As a general guidance, the machine shall be held in a manner consistent with day-along use of the machine during the vibration measurement. Powered brush cutters shall be held upright as shown in Figure 1 (ISO 22867:2008). However this is not a representative position for example in case of hillside cutting that is common especially during motorway maintenance. Very few studies have been carried out to investigate the effect of the operation Measuring the vibration of a brush cutter in different operation modes