The evaluation of vehicle vibration and seats

Measurements of vibration in a variety of road vehicles in common use are compared with the guidance provided in ISO 2631-2974 (E) (Guide for the evaluation of human exposure to vibration). For typical journey durations many of the vibration levels are in excess of the levels corresponding to the 'reduced comfort boundaries' and 'fatigue decreased proficiency boundaries' defined in the ISO Standard. Some of the problems inherent in comparing the measured vibration levels with the Standard are outlined and the need for a revised format for the Standard is discussed. A method of summarising the vibration attenuation of vehicle seats is defined and it is shown that the isolation provided by many of the seats of the 16 vehicles used in the study is poor.