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The design and analysis of most engineered systems involves many and sometimes diverse technical disciplines. For example, in the design of a fluid power system, the input to the system is usually some type of prime mover. In addition, the output may include gears, linkage, etc. The output may be used in a feedback circuit which will normally encompass instrumentation, logic elements, and controllers. In order to evaluate the total performance of such systems analytically, a software package must be available which can unify the interactions of these diverse components. This paper will present a new computer program which will unify hydraulic, pneumatic, electronic, and mechanical components permitting the analysis of complete engineered systems on a P.C. Several example systems will be shown which originate in actual machinery designs. These example systems will be simulated and output type information will be presented.

The selection of a proper fluid to be used in a hydraulic system is an important part of any design effort. The hydraulic fluid must normally transmit, transform, and control the power from the system input to the output. In addition, the fluid is expected to provide lubrication and antiwear protection to many of the other components in the system. Although there are at least 22 parameters which describe a hydraulic fluid, most of these parameters are well defined. However, the antiwear and lubrication properties of a hydraulic fluid deserve more discussion. There are several test methods which have been developed to assess the antiwear properties of liquids. Most of these procedures are intended to evaluate fluids other than those directed toward use in a hydraulic system. This paper will present a bench type wear test method designed to overcome the recognized problems of other wear test procedures.

Every hydraulic system use requires a pump to supply the necessary flow and support the imposed pressure cycle. Therefore the performance of the pump in a hydraulic system is critical to the overall performance of the system. It is a well known fact that the performance of a hydraulic pump is influenced by both the speed at which it is operating and the pressure to which it is subjected. This paper evaluates the volumetric efficiency of a hydraulic pump using both the fundamental expressions which are generally accepted and actual data test data. The widely accepted equation for pump leakage is presented along with an expression that includes the parameter of speed. Results obtained using a pressure-loaded gear pump are used to compare and evaluate the analytical expressions. This comparison reveals a significant influence of speed at high pressures on the volumetric efficiency of the pump.