Hydraulic servo cylinders are widely used in high-performance industrial applications, such as machine tools, test benches for various components, industrial robots, autonomous production systems, and special laboratory equipment. They are selected in all scenarios that require smooth motion, fast dynamic response, and the ability to withstand radial forces.
A key element in their proper operation is the use of pocketed hydrostatic bearings installed at the rod ends. These components are essential to support high loads, minimize friction, eliminate wear, and ensure a controlled, smooth actuator displacement.
However, designing and manufacturing these bearings is challenging. Their performance depends on tight tolerances, which are needed to sustain cylinder loads and reduce flow losses. In hydraulic systems, lubricated interfaces are among the most critical aspects, significantly influencing both efficiency and component reliability.
This study presents a 2D fluid dynamic model of hydrostatic bearings, developed in Modelica and entirely solved in the OpenModelica environment. It represents the first phase of a broader research project aimed at building both a virtual model and a physical test bench for pocketed hydrostatic bearings.
The model is designed to investigate critical operating conditions of servo cylinders and to support the design and optimization process. Results highlight the strong influence of eccentricity and machining tolerances, showing how crucial it is to carefully select the design parameters to achieve optimal performance.
In collaboration with Cabol Fluid Engineering, the model has been tested and validated, leading to the development of a virtual design tool for engineers. This tool enables users to simulate various configurations and make informed design choices.
Beyond its specific contributions to hydrostatic bearing design, the work also showcases an innovative use of OpenModelica—not just as an equation solver, but as the core engine of an industrial application that assists engineers in exploring and validating design options.
👉 Download the full paper in PDF to learn more about the methodology, results, and practical applications of the developed model.
