SELECTION PROCEDURE OF HYDRAULIC VALVES FOR TRIBOLOGICAL RESEARCH

A number of methods are available to test the wear resistance of different hydraulic components, along with the known hydraulic fluid. Some of the methods have become standardised, while others are dedicated and of an internal nature, linked to a single manufacturer, either components or fluid. However, none of the represented methods allows a comprehensive insight into developments in all components of the hydraulic system. Tests concerned with lubricating properties and the service-lives of hydraulic components, usually use techniques and procedures similar to those occurring during the actual component usages, and are based mainly on testing the pumps – s. c. tribological standardised pump tests methods based on precisely defined pump types. Tribological tests of hydraulic valves, especially continuously acting control valves, also highly-loaded components of a hydraulic system, are mentioned very rarely, or not at all. For valve testing purposes it is necessary first, to establish the appropriate testing methodology and the corresponding test rig, to determine the correlations between operating conditions as input variables and valve performance criteria as output variables during a preliminary test series. In order to provide a comparison of tribological testing results, it is necessary to select valves with exactly the same characteristics for these tests. In this paper, the selection process of valves with the same characteristics is presented in more detail. Only in this way, will the results of a long-lasting tribological testing be comparable, and the conclusions credible.