This paper aims to investigate failures induced by vibrations on machines, focusing on agricultural ones. The research on literature has brought to light a considerable amount of data on the driven vehicles and not much on the operating machines, including the ones that we looked for. For this reason, it was decided to direct a survey with the people who work with agricultural machinery every day: operators, sub-contractors, and producers. They were asked about the most frequent breakage, particularly in relation to the rotary harrow, the topic of this work. The questionnaire results showed the types of failures the harrow is most vulnerable to, indicating the times of failure and reparation and the need to set up a potentially useful preventive maintenance supporting system on these machines. Part of the work was then focused on the proposition of a method to investigate bearing failures in the rotary harrow, considering that these have been analyzed in the technical literature and in the survey as the most at-risk components. The proposed method in this work serves as a beginning for the development of a future on board sent-shore-based maintenance system for continuous monitoring of the bearing.

It is widely recognized in the field of safety at workplace that professional exposure to whole-body vibration (WBV) may generate unfavorable effects on workers' health. Among many involved categories, professional drivers are clearly one of the most exposed groups, as exposure time may last for the whole working period. This research is based on the results of measurements gathered from 14 subjects who drove vehicles for urban use. In particular, in order to highlight the effects of vehicle armoring on professional WBV dose, two sampling campaigns were carried out. In the first case, a car for standard use was used while, in the second one, another vehicle of the same model was modified with the installation of the armor-plate for ballistic protection. The assessment was carried out in accordance with ISO 2631-1(97), under the same boundary conditions, and finally the daily exposure parameter was assessed. Furthermore, to allow a comparison independent of individual factors, the exposed subjects were divided into homogeneous groups of different classes based on their body weight and height. The results obtained showed that WBV exposure is clearly connected with vehicle characteristics. In particular, the installation of bulletproof armor, contributing to a change in the car mass distribution and its total weight, determines a generalized reduction of professional dose. This reduction may be quantified in a range from 10% to 20% depending on the individual characteristics of the driver.

The problem of the whole body vibration (WBV) exposure for operators in the workplace has been analyzed by many researchers that have studied for a long time the complex relationships between this phenomenon and human health risks. Previous studies have shown that drivers of different vehicles, in particular operators in mining activities, are afflicted by serious musculoskeletal injuries due to WBV exposure. Criteria in order to measure and assess equivalent daily exposure, associated with different operations of the vehicles, are referred to standards ISO2631-1, based on method of the frequencyweighted equivalent continuous root mean squared (r.m.s.) acceleration. Numerous studies point out the complexity to outline a clear relationship between WBV exposure and the human health disorders. An experimental campaign was realized in a limestone quarry near Rome and vibration measurements were recorded on four different mining vehicles (dumper, jeep, digger and puncher machine). The vibratory signal was taken at the seat operator/seat interface (X, Y and Z axes) in accordance with the ISO 2631-1 during daily quarry operations. The data obtained were elaborated and finally the results are presented in order to evidence the difference of WBV exposure between the specific operating tasks and some methods for the purpose of exposure dose reduction are suggested.

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The estimation of the transmissibility of antivibration gloves requires the use of handheld adaptors for holding the accelerometer and assure that it is correctly positioned at the palm level of the hand. The marketplace proposes only few adaptors, specially made for hand-arm vibration measures, so researchers often had to make their proper homemade adaptors to performing their experiments on the gloves' transmissibility. A way to easily build hard-plastic adaptors is given by the possibility to use 3D printers, but in the literature, there is a lack of information about their properties. This paper investigates the properties of 3-D printed adaptors, confronting different materials among the most used (PLA, ABS, and Nylon), and evaluates possible changes of their performance at different infill densities. Results show that 3-D printed adaptors can be a valid alternative to those present on the market. At middle-low frequencies (10 Hz-400 Hz) their transmissibility values are inside the range ± 0.05. No significant differences were found between the transmissibility of those printed at 50% or 100% of infill, especially when the acceleration is Wh weighted. It has been also experimented a simple solution that aims to reduce possible misalignments of the adaptor when inserted inside the glove. Two external landmarks were designed in order to have a visual check of the position of the adaptor. The first, coming out from the glove through a little slit, was made for checking about the rotation on the Y-Z plane, while the second, parallel to the wrist, was made for checking rotation on the X-Z plane. The statistical analysis, among 30 measures performed by three operators holding the instrumented handle of a mono-axial shaker, supports the idea that the first landmark can help to achieve a better alignment of the adaptor, limiting its rotation along the Y-Z plane. Lesser evidence resulted on the reduction of the misalignment on the X-Z plane, due to the use of the second landmark. A possible reason is the small thickness of the ordinary leather glove used in the tests, which produces too little misalignments angles for being checked by the adaptor's landmark. Some further tests can be carried out using anti-vibration gloves, generally made of thicker and softer materials.