Defines a laboratory method for measuring and evaluating the effectiveness of the seat suspension in reducing the vertical whole-body vibration transmitted to the operator of earth-moving machines at frequencies between 1 Hz and 20 Hz . Spectral classes are given for e.g articulated frame dumpers, crawler loaders, graders, wheel dozers, backhoe-loaders, compact loaders, skid-steer loaders, rigid frame dumpers and scrapers without axle or frame suspension. Different operating mass is given in the various classes (where necessary).