The European Machinery Directive requires vibration emissions on mobile machinery to be measured at the following vibration emission points: seat, controls/steering wheel, where applicable the location of the standing operator. The objective of this joint project was to develop a test procedure for this purpose in which the mobile machinery would be moved over existing natural test tracks. The mobility of the machine and the track surface are the principal sources of vibration emissions.
In the course of the joint project, the parties to it measured the whole-body and hand-arm vibration emissions on a number of machines and a range of test tracks. The BG Institute for Occupational Safety (BIA) measured the whole-body and hand-arm vibration emissions (weighted vibration acceleration) at the driver's workplace on two aircraft tow tractors of different sizes over three different test tracks and at different speeds. The weighted acceleration values were measured on a large pavement profiler under different profiling conditions in asphalt, and on a small pavement profiler in asphalt and concrete. Ingemansson Technology AB (Sweden) measured the whole-body and hand-arm vibration emissions on four earthmoving machines (wheel loaders and dump-trucks) and five soil compaction machines over a number of test tracks and at different speeds. The Austrian Research and Testing Center (Arsenal) measured the whole-body and the hand-arm vibration emissions on two agricultural tractors, two small dump-trucks, and two piste preparation machines. In addition, the seat characteristics of two seats under operational conditions were compared with the results of standardized laboratory seat tests.
Natural test tracks are suitable in principle for measurement of the vibration emissions of mobile machinery in accordance with the European Machinery Directive. A condition is that a defined vibration excitation be measured at a test point close to the source of excitation (e.g. wheel bearing housing, profiling drum bearing). Unsuitable, extreme test tracks can thus be excluded. The results of the laboratory tests performed on seats according to standard conditions may differ considerably from those of measurements performed in operational use, depending upon the frequency spectrum and the excitation intensity. Selective use for estimation of the stress upon the driver on the seat at a given vibration excitation at the seat mounting point is therefore possible only in individual, previously studied cases. A generic test procedure containing specifications of essential measurement conditions was developed and submitted to the responsible European standardization committee, CEN TC 231 (vibration and shock) (see also Annex of EN 1032 concerning the generic test procedure for vibration emissions employing natural test tracks).
Interner Bericht für die Europäische Kommission
-cross sectoral-Type of hazard:
Normung, Prüfverfahren, VibrationDescription, key words:
Vibration emissions, EU Machinery Directive, natural test tracks, monitoring of vibration excitation, regression analyses, correlation analyses, suitability of the test track, measurement of vibration emissions, aircraft tow tractor, pavement profiler