root mean square acceleration (rms), crest factor and hand- arm vibration dose value in tiller users

the purpose of this study was to assess exposure to hand-arm vibration in tiller users, forty users of tiller in northeastern provinces of iran were examined to measure hand-arm vibration parameters such as root mean square acceleration (rms), total equivalent acceleration, vibration dose value (vdv) and crest factor in three directions (x, y, and z) and various operating modes for comparing them with the relevant permitted standard levels. the hand-arm vibration measurement was done according to the standards iso 5349-1 and iso 5349-2. the obtained results indicated that the exposure level in three modes of rota-tilling, transportation and idling were equal to 16.95, 14.16 and 8.65 m/s2, respectively. in all measurement modes, the exposure to vibration in the direction x was greater than that of y and z. moreover, the average crest factor was calculated less than six. the highest vibration dose values were measured in rota-tilling mode when the tiller was in 2nd  gear (60.76 m/s1.75) and 1st gear (56.83 m/s1.75). the results indicated that the permitted working time was only few seconds and there was a risk of musculoskeletal disorders. the present study emphasizes on the need for interventional and control managerial measures to eliminate or reduce hand-arm vibration transmitted to the tiller users' hands for avoiding major problems such as musculoskeletal disorders, discomfort and  premature fatigue. in this regard, further studies are required to identify vibration sources in different types of tillers.