Whole-body vibration exposure among tractor operators at the tractor seat: Impact of tillage operation, speed and operator weight

This study presents a comprehensive evaluation of whole-body vibration (WBV) exposure among operators of the URSUS 5312 agricultural tractor during primary and secondary tillage operations, including ploughing, harrowing, and ridging. The investigation focuses on the influence of operational variables—namely forward velocity and operator body mass—on the transmission of vibrational energy through the operator’s seat interface. Vibration data were acquired using GM63A vibration meter mounted on the tractor seat base, and analysed in accordance with ISO 2631-1 standards to assess health risk thresholds. Results demonstrate that ploughing at the maximum operational speed of 6.25 kmh⁻¹ induced the highest seat-transmitted vibration, with a dominant frequency of 30.52 Hz, whereas harrowing at the minimum speed of 2.25 kmh⁻¹ produced the lowest vibration magnitude (5.52 Hz). A strong positive correlation was observed between travel speed and WBV intensity. Additionally, operator mass significantly influenced vibration transmission characteristics, with a heavier operator (96 kg) experiencing elevated vibrational amplitudes (25.52 Hz) relative to a lighter operator (76 kg), who recorded a substantially lower frequency (7.87 Hz). Measured WBV levels frequently exceeded the Exposure Action Value (EAV) specified by international vibration exposure standards, underscoring the potential for cumulative musculoskeletal strain, spinal degradation, and other occupational health risks. Accordingly, the study recommends limiting continuous field operation to no more than 3 hours per day, with intermittent rest periods of at least 30 minutes to mitigate adverse health effects.