The paper presents the results of evaluation of admissible misalignments of two neuralgic bearings of a great power turbine set. The areas of admissible misalignments have been evaluated by numerical analysis of the discrete model of the machine with the aid of a package of MESWIR computer codes. For this purpose the criteria of “tolerable misalignment” were formulated with regard to permissible bearing vibrations and with regard to permissible static bearing loads. The areas of tolerable misalignments of the two bearings are presented in the graphs as the envelopes of maximum permissible bearing vibration and permissible bearing load, separately. The envelopes limits misalignments of the bearings to any direction regarded as the superposition of simultaneous vertical and horizontal displacements. Dimensions and the shapes of the areas are different for the two analyzed bearings and also depend on the fact, whether the area was calculated with regard to criterion of bearing vibration or criterion of bearing load. Especially interesting and not expected are shapes of the areas calculated with regard to vibration criterion. In this case after reaching the maximum permissible vibration at some bearing misalignment, further misalignment of the bearing may result in decreasing of vibration level. The method and procedure applied in the investigations allow determining how sensitive is a rotating multi-support machine to random misalignment of bearings. Basing on the method it is possible to correct the location of particular bearings to optimize tolerable bearing misalignment areas. Besides the research makes it possible to formulate a system of diagnostic relations connected with the bearing misalignment defects, which can make the knowledge basis for a diagnostic system.

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