. , Modelling and Analysis of the Dynamie Properties of Mobile Hydraulic Systems. ABSTRACT Petter Krus Division of Fluid Power Controi Department of Mechanica1 Engineering Linköping University S-581 83 Linköping, Sweden 1 A clear trend in mobile fluid power systems is that the advantages of digital controI of fluid power systems are recognized. One obvious reason for this is that digital controi makes the controi systems more flexible compared to systems with hydromechanical controI. Another reason is that the new generations of electrohydraulic signal transformers, such as proponional valves, are mueh more reliable and robust than before. For suceessful implementation of digital controi systems it is, however. important to develop the knowledge of the dynamic properties of fluid power components and systems. In this paper a general model of mobile hydraulic systems is described. Load sensing and eons tant pressure systems can be derived as special cases from this model. Within this model it is also possible to investigate influence of different valve systems as weIl as the influence of different types of loads. Measurement and analysis methods for the dynamic properties of a generalload are also described. The model provide information with which il is possible to design effective control systems for pumps and for improved load control including position control.