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This paper discusses the importance of vibration transmitted from the ground to the driver from the perspective of human whole-body vibration (WBV). The scope of analysis is to compare the main vehicle frequencies with those important from the human vibration health and comfort point of view. That was performed by mapping the vibration transmissibility present in different sub sections of the vehicle. The first is the transmissibility between the axles and the chassis rail, the following between the chassis rail and the cabin. The last would be between the cabin and the drivers' seat, although that was not possible from the acquisition point of view. The vehicles measured have mechanical suspension and elastomeric cabin coupling. It is known that all suspension systems in vehicle are highly nonlinear, although here linear dynamic analysis methods were used.

Control valves are one of the major sources of noise generation in hydraulic systems. A valve design that controls the factors that trigger noise during flow throttling is discussed in this paper. The proposed valve geometry avoids noise generation primarily by maintaining laminar flow and avoiding cavitation and boundary layer separation through the flow passage. The valve design consists of a variable annular tapered configuration that controls pressure and flow quietly. Experimental verification conducted in a two-way valve shows the effectiveness of the valve design in maintaining airborne noise levels below 40 dbA at high pressure and high flows.

This paper is concerned with the synergistic effects of pump wear modes. The objective is to investigate the wear produced by cavitation, adhesion, abrasion, and corrosion and to verify a proposed model of the synergistic pump wear process. The approach followed includes identification of the combined effects of different wear modes (synergisms) in a pump and the development of a synergistic wear model that includes pump operating and environmental conditions as trigger factors of wear modes. An experimental program was designed to evaluate the cavitation, adhesion, and corrosion wear effects in conjunction with the abrasive wear produced in a pump by measuring wear debris, particle size and gravimetric levels of fluid. The generation of wear was traced to different pump locations. The results obtained here suggest that improved pump design and longer pump service life can be obtained when synergisms between failure modes are properly understood.

This paper presents an Integrated Diagnostic Methodology (IDM) for analyzing hydraulic systems. The IDM fuses information from condition monitoring, system diagnosis, failure prognosis, and prescriptive action to provide a means to detect failure modes (in-situ), failure state, time to failure, and prescriptive maintenance (if needed). Information about the pump condition is determined through time series analysis of the pressure pulsation of the pump. Using fuzzy pattern recognition techniques, failure symptoms are detected and classified into known failure modes. Similarly, state of failure is categorized using a fuzzy reasoning method. Finally, a trend analysis is made to forecast time to failure, while a set of rules is used to decide the proper maintenance action. As an example of the IDM procedure, experimental results monitoring a gear pump are presented.