Comfort Evaluation Criteria for Pitching Vibration Damping of Agricultural Tractors

The market of agricultural machinery continuously increases its demands for better comfort and higher safety for the end user. This poses a challenge for OEM's in order to develop new suspension and damping techniques and, indeed, how to quantify good ride comfort. The standardized method to evaluate comfort is utilizing ISO 2631-1, but due to the frequency weighting filters include in this standard, it does not capture the effect of pitching vibration damping. In this paper, a comfort evaluation criterion for pitching vibration damping of agricultural tractors is presented. The aim is to quantify ride comfort when developing solutions for damping of pitching vibrations in order to compare different strategies.The new criterion was utilized during development of active pitch damping by operating the electro-hydraulic hitch valve of an agricultural tractor. The ISO 5008 Smooth Track and asphalt road served as boundary conditions for the development work. The developed criteria shows good correlation with the subjective comments from a number of test drivers.