| Summary: | It is well established that the differential cylinder area in pump-controlled single-rod actuators creates the need of correctly switching the connections between the main circuit lines and a charge circuit, in order to provide means for equalising the flows into and out of the pump and the actuator. Many attempts to automatically switch the charge circuit connections to either cap- and rod-sides of the hydraulic cylinder have been made through the years. However, in many of these attempts, strong oscillations in the cylinder motion were observed when operational quadrants were changed under some particular velocity and force conditions. In this paper, we perform a thorough numerical analysis for some representative pump-controlled single-rod actuators. The goal is to understand the causes of undesirable behaviour of several circuits under certain operating situations. We show through comprehensive simulations that all but one circuit design produces undesirable oscillatory results under these circumstances. This paper is built upon and complements a previously published paper by the same authors on this important subject.
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