Whole-body vibration of tractor drivers during harrowing

The seat vibration of nine tractors was investigated while drivers harrowed fields in eastern Finland. The vibration acceleration of the tractor driver's seat was measured simultaneously along three mutually perpendicular axes. The triaxial seat-accelerometer was used for the measurements. The vibration signals were amplified with charge amplifiers and recorded with an FM tape recorder. The samples were analyzed with a real-time analyzer. In all cases, the average vibration of the seat exceeded the 8-hour "fatigue-decreased proficiency boundary" specified in the international standard ISO 2631/1. The instantaneous accelerations of the most harmful one-third octave band of vibration were sometimes two- to threefold compared with the average.