A study was conducted to quantify whole-body Vibration (WBV) emission and likely operator daily exposure levels associated with the normal operation of self-propelled forage harvesters. A customer survey was distributed to purchasers of recent machines, to determine information concerning typical machine usage and operator perception of WBV levels. Comprehensive WBV measurements were made on 6 working machines, each encompassing 4-5 hours of commercial activity, to provide representative samples of WBV time-histories. Frequency analysis of the vibration data and direct observation provided information on the potential and need for reducing operator WBV exposure in each instance.
Self-propelled forage harvester whole-body vibration emission levels were found to be relatively moderate compared to those encountered upon other agricultural vehicles. Vibration levels resulting from in-field harvesting (grass or maize forage harvesting) were generally lower than those generated during on-road travel. Nonetheless, whilst moderate, the WBV levels are sufficiently high to ensure that (as with most other agricultural vehicles), the PA(V)D exposure action value (EAV) will be exceeded during normal daily operation, necessitating certain prescribed actions on the part of employers. However, given the typical 80%:20% breakdown of forage harvester in-field vs. on-road use, it is extremely unlikely that either the WBV daily exposure limit value (ELV) or the recognised risk threshold level of 17 VDV will be reached or exceeded during a normal (12 – 14 hour) working day.
Opportunities potentially exist to reduce (Z-axis) whole-body vibration levels and improve operator ride comfort, by modifying the characteristics of the suspended seats fitted to this type of machine. Other opportunities to reduce X-axis (pitch) vibration, particularly during on-road travel, are also worthy of investigation.
This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the author alone and do not necessarily reflect HSE policy.
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