Durability of vibration-reducing drivers´ seats in earth moving machinery

Status:

completed 12/2003

Aims:

Until now there were no reliable statements about the durability of vibration reducing drivers´ seats in earth moving machinery. Correspondingly no binding standards could be formulated. Therefore the topic was suggested to be dealt with on international level with the intention, to conduct an ISO-standardisation project regarding the durability of drivers´ seats in earth moving machinery. A preliminary study with measurements of the seats´ vibration behavior under real-life conditions and in the laboratory had the following participants: The German Institution for Statutory Accident Insurance and Prevention in the building trade, a renowned German seat manufacturer and various users of earth moving machinery.

Activities/Methods:

The functioning of seats in operational use was examined on 14 different earth moving machineries in adequate intervals, beginning with the commencement of operation of the machinery. Testing was based on the specifications of the corresponding international test standard for earth moving machinery. The vibration exposure was measured at the seat mounting point (chassis) and on the seat between the surface of the seat and the driver. In addition to real-life testing, the seats were repeatedly dismounted, subjected to laboratory tests according to the test standard and mounted again in the vehicles. Testing was conducted on account of the latest modifications of the test standard and the frequency weighting.

Results:

The essential conclusion to date from the study is that following a longer period in service, the seats either retain their function virtually unchanged, or are clearly defective. According to the results obtained to date, a gradual deterioration in the vibration attenuation behaviour is virtually never encountered. On seats which remain serviceable, the deviations in the seat transmission factor following a longer period in service are in the order of ±10%, i.e. little higher than the variation observed at manufacture. Skilled visual inspection and simple function checks performed at defined intervals in the field generally enable defective seats to be identified in good time throughout their useful life. The party commissioning the study is in possession of the internal reports containing the results of vibration measurements obtained by the BIA.

Publications:

Kummer, W.; Meyer, L.;Schmidt, W.: Langzeituntersuchungen der Schwingungsdämpfung von Fahrersitzen auf Erdbaumaschinen. Tiefbau (2005) Nr. 9, S. 534-538

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