This paper presents a detailed experimental investigation of seat-transmitted whole-body vibration (WBV) exposure in an agricultural tractor under controlled and repeatable field conditions. A medium-power agricultural tractor (42 kW rated engine power) equipped with radial-ply rear tyres (14.9–28) inflated to 120 kPa and front tyres (6.00–16) inflated to 180 kPa was used. The tractor was fitted with a mechanical spring–damper seat suspension adjusted to a 75 kg operator mass. Measurements were conducted with a human operator to realistically capture biodynamic coupling effects. Tri-axial accelerations were recorded at the seat–operator interface during no-load travel and tillage operations on cultivated loamy soil with average surface roughness of 18–25 mm. Frequency-weighted RMS acceleration, mean values, standard deviations, and 95% confidence intervals were evaluated in accordance with ISO 2631-1. Results show that vertical RMS accelerations reached up to 1.12 m/s², while horizontal components exceeded 0.85 m/s² during tillage, surpassing reduced comfort boundaries. The findings provide quantitative guidance for future development of multi-axis and semi-active tractor seat suspension systems.

Whole-body vibration, agricultural tractor, seat vibration, ISO 2631, ride comfort, field experiments.

Agricultural tractors expose operators to severe whole-body vibration due to uneven terrain, soil-implement interaction forces, and the absence of primary suspension systems. Prolonged WBV exposure is associated with fatigue, discomfort, and chronic musculoskeletal disorders [1]. While previous studies have reported tractor vibration levels, limited attention has been paid to detailed operating conditions and statistical reporting. This study addresses these gaps through a reproducible experimental framework [2].

Test Tractor and Operating Conditions. Experiments were conducted using a 42 kW agricultural tractor operating at engine speeds of 1600–2000 rpm. Tests were performed on cultivated loamy soil with moisture content of 14–16%. Both no-load travel and rotavator-based tillage operations were evaluated at forward speeds of 3, 5, and 7 km/h [3-5].

Operator and Seat Configuration. Measurements were carried out with a human operator (mass 75 ± 3 kg) seated normally with hands on the steering wheel. The mechanical seat suspension was adjusted according to manufacturer recommendations [8-10]. This configuration ensured realistic biodynamic interaction compared to dummy or unloaded seat tests [6].

Instrumentation and Data Acquisition. Tri-axial accelerometers were mounted at the seat–operator interface. Signals were sampled at 1000 Hz. Each test condition was repeated five times to ensure statistical reliability.

Data Analysis. Frequency-weighted RMS accelerations were calculated following ISO 2631-1. Mean values, standard deviations, and 95% confidence intervals were computed for each axis.

Test Tractor and Operating Conditions. Experiments were conducted using a 42 kW agricultural tractor operating at engine speeds of 1600–2000 rpm. Tests were performed on cultivated loamy soil with moisture content of 14–16%. Both no-load travel and rotavator-based tillage operations were evaluated at forward speeds of 3, 5, and 7 km/h [3-5].

Operator and Seat Configuration. Measurements were carried out with a human operator (mass 75 ± 3 kg) seated normally with hands on the steering wheel. The mechanical seat suspension was adjusted according to manufacturer recommendations [8-10]. This configuration ensured realistic biodynamic interaction compared to dummy or unloaded seat tests [6].

Instrumentation and Data Acquisition. Tri-axial accelerometers were mounted at the seat–operator interface. Signals were sampled at 1000 Hz. Each test condition was repeated five times to ensure statistical reliability.

Data Analysis. Frequency-weighted RMS accelerations were calculated following ISO 2631-1. Mean values, standard deviations, and 95% confidence intervals were computed for each axis.

The revised study provides statistically robust and reproducible WBV data. Quantitative findings confirm the need for advanced seat suspension systems to enhance operator comfort and safety.

Although the study provides comprehensive field-based vibration data, it is limited to a single tractor category and soil type. Future studies should consider multiple tractor models, varying soil conditions, and long-duration exposure assessments. Integration of subjective comfort evaluations with objective vibration metrics would further enhance the robustness of future research.

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