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A pressure accumulator allows system designers to increase the potential energy of a trapped gas or fluid, and to release that stored energy as required by the working circuit. Pressure accumulators also serve as an important component in mobile and industrial hydraulic circuits, acting to suppress fluid surges generated by abrupt movement of the load. The design of pressure accumulators can be modified somewhat to provide additional functionality, however. A partitioned accumulator is described in this paper which can be used with a pilot operated valve to accumulate fluid in several pressure ranges, and can supply fluid in the pressure range required by the working circuit. This design provides for the storage of separate volumes of pressurized fluid, while allowing controlled pressure interaction between the fluid volumes.

Commercial suspension systems have used metal springs for many years. More recently, suspensions using air springs have demonstrated superior ride qualities. Metal springs provide adequate support for the fully loaded vehicle, but do not adequately vary the support for smaller loads. Air springs provide variable support of the load, but allow more roll as the vehicle corners. Fluid spring suspension components will be examined in this paper which eliminate the vehicle's tendency to roll and provide variable support for the sprung load. The fluid spring operates as a biased spring. Static load variations and forces acting directly on the sprung load are passed through the fluid spring to the wheel support without causing it to extend or retract. The fluid spring extends or retracts quickly however, to track irregularities in the road and to maintain support equal to the weight of the sprung load at each moment. In this manner, it functions as a viable ‘sky-hook’ suspension.

Conventionally sprung vehicles are subject to rolling and pitching of the sprung load as the vehicle corners and accelerates, respectively. Designs which incorporate active elements seek to control these movements, frequently resulting in compromised performance or reduced fuel economy. This paper considers the possible replacement of conventional springs, shocks, and anti-sway bars with specified fluid spring components. The fluid spring components offer biased response to dynamic load variations in the following manner: provide support of the sprung load equal to the magnitude of the load at each moment, and either compressing readily to absorb upward forces originating in the wheel assembly which exceed the magnitude of the load at that moment, or extending rapidly to provide support equal to the magnitude of the load at that moment, in the event the wheel assembly tracks through a hole.