Electric shakers to facilitate drupes harvesting: measurement of the vibrations transmitted to the hand-arm system

Given the widespread use of handheld vibrating machines for drupe harvesting due to the productivity gain they can ensure with respect to the manual harvesting, and given the vibration exposure risk for operators during their use, some laboratory tests were carried out aimed at measuring the vibrations transmitted to the hand-arm system by some new models powered by electrical motors recently introduced on the market. The experimental tests were arranged according to a factorial design so to evaluate the effects of three types of harvesting heads, different for number of operating tools and oscillating system, and three types of bars, different for material and diameter. The vibrations were measured in two points, next to the hand positions on the bar in working conditions. To smooth the influence of external factors, the machines were idle operated by the same person. The results showed that the weighed global acceleration, even if not measured during harvesting, was quite high with respect the threshold limit values established by the current regulations. Moreover, the differences among the harvesting heads (from 18.0 to 23.3 m/s2) and the measuring points (16.6 and 24.4 m/s2) were statistically significant, but not those among the bars (on average, 20.5 m/s2).